The T1 Turret and the New Arrivals
"Its name is T1." Yun Yeong-su proudly pulled back the gray waterproof tarp.
"...!"
"Wondering what this is, right?"
"Uh... honestly, yes."
The T1 Turret, which had an ominously(?) utilitarian name, looked like a large rectangular metal box, a little over 1.5 meters wide and 60 to 70 centimeters in height and depth. Seen from the front, where two gun barrels protruded, it had the shape of an isosceles trapezoid. From the side, it looked like a sleek, solid metal box, save for a ventilation duct and a fixed latch mechanism.
"I made it out of aluminum alloy and stainless steel. This shape is the best for withstanding four-season temperatures, snow, and rain. I haven't put the outer casing on yet. I'm going to cover it with a waterproof camouflage tarp."
Click! As Baek Ha-il released the latch and lifted the top cover, the complex interior was finally revealed, housing two air rifles side-by-side.
"See this motor here? It's a harmonic drive servo motor. This rotates the turret 360 degrees." Baek Ha-il pointed to another motor and continued, "This is a high-precision BLDC motor. It adjusts the vertical tilt by plus or minus 30 degrees."
"The response time is 0.8 to 1.1 seconds. It gets even faster if it's already locked onto a target and tracking it. That's the power of the motor and the program combined."
"The magazine is solenoid-operated. It’s more of an automatic ammunition feeder than a magazine. Anyway, it weighs just over 20 kilograms, so we can install it at our guard posts, on the roof of the shelter building, or on the perimeter fence. If we use proper camouflage and concealment, we can even install it down by the main entrance road. Yeong-su."
"Yes, sensei. Ahem." Yun Yeong-su, having been called upon, rested his hand on the T1 and continued. "The T1 Turret operates based on real-time video captured by the high-performance PTZ camera the boss installed at the guard post, along with laser distance measurement data."
"I know that much."
"Ah, sorry. Anyway, the effective range of the new air rifle Baek-sensei made for the T1 is 180 meters, right?"
"That's right."
"But if Akina calibrates it, 200 meters is no problem."
"Oh?"
"Really?"
As Jun-ho and Baek Ha-il showed interest, Yun Yeong-su spoke even more excitedly. "Yep. It calculates everything—muzzle velocity, air resistance, and target movement—via a real-time data link to calibrate the firing point. Akina uses the microcontroller and servo controller I personally tweaked in an amazing way. The Raspberry Pi 5 and Jetson Orin Nano support PWM output to the servo controller board..."
Jun-ho quickly cut off the "humanities-major-phobia" he was experiencing for the first time in a while. "So, can this attack cars or drones too?"
"Yes. It’s possible by calculating the direction of movement and firing ahead."
"Lead shooting."
"Yes, that. Anyway, cars or drones don't just come in at 60 or 70 kilometers per hour from the start. Drones, especially, fly at cruising speeds for reconnaissance and have a constant direction of movement. Cars are on the road, so it's easy to predict and shoot."
"Good." Jun-ho smiled and turned to Baek Ha-il. "Then we're installing these on the ground drones made from the kids' electric cars, right? Is the weight an issue?"
"No. Even though they're for kids, they can handle a load of up to 50 kilograms. They were made for two kids to ride front and back. Even with this and the industrial air tank, it won't exceed 30 kilograms. So..." Baek Ha-il pointed to the metal stacked in one corner of the workshop. "That’s AR500 steel plate. If we use that to make bulletproof plates to wrap around the front and sides of the electric car, it'll land right at 40 kilograms."
"What about speed and operating time?"
"I modified the motor, so it'll do 20 kilometers per hour for 30 to 40 minutes. But you wouldn't really be moving and shooting at that speed constantly, would you?"
"That's true."
The T1 Turret itself, and the ground drones equipped with the T1, were primarily for defense. Even when moving, they would likely travel at a slow speed similar to a person walking.
"Then an hour is fine. Adding a bit more battery might add 20 minutes, but that would make it too heavy and put a strain on the chassis."
"As it is now is perfect."
There would be no scenario where these electric ground drones would be in combat for over an hour. Above all:
"Is it easy to replicate the air rifles now?"
"Yeah. I can make 10 a day. If that friend Jeong-woo helps, maybe 20."
"Then let's make about 100, enough for the guard posts, the shelter defense turrets, and the electric ground drones. We have plenty of electric cars anyway."
It was better to have plenty and rotate them in an emergency. "Let's do that. I wondered why you bought 50 of those kids' electric cars, but you really did have a plan for everything."
"If we want to use them for several years, we'll definitely need spare parts. For now, just make 10 electric ground drones."
"Understood. Yeong-su, is your program and everything else ready?"
"Yes. I've linked it with Akina. I just need to fix a few bugs. It’s a bit complex and time-consuming at first, but since it's deep learning, it'll be ready soon after a few tests and bug fixes."
Jun-ho nodded. "Good. Don't rush it too much. There's no one coming here for a while anyway, so it's fine. If zombies enter our zone, Jun-hyeok or I can just go take care of them."
"Yes. It should take three or four days at most. From then on, you and Chief Choi can just churn them out."
At Yun Yeong-su's words, Baek Ha-il looked at him with an incredulous expression. "Do you think it's just a matter of churning them out? Do you have any idea how hard it is to fine-tune all the various sensors, not to mention the motors? Huh? Fine. Tuning."
"Akina does that too if I record the work process and input the results, though?"
"What? Really?"
To the wide-eyed Baek Ha-il, Yun Yeong-su tilted his head and said, "Sensei, you didn't know that yet? Ah, this won't do."
Yun Yeong-su, with his signature smug face, manipulated the small laptop he was holding. "Fine-tuning? That's Akina's specialty. Just film it with the CCTV and the workbench camera. Then it analyzes the various sensor data generated during assembly in real-time and suggests the optimal calibration values. Motor torque? Sensor sensitivity? Akina finds them itself and reflects them in the control system. Baek-sensei, you don't have to go through trial and error one by one."
"Holy..."
"It can even automatically control the machines and equipment connected to the network in the workshop, you know? You installed several CCTVs there, right? It tells you in real-time through those and the sensors. It even does optimal turret placement, drone mission allocation, and optimal control."
"Really? That's insane..."
Yun Yeong-su, feeling even more triumphant, pointed at the laptop screen. "Chief Choi and Sensei just need to build them. It can catch everything from equipment malfunctions to damage by fusing vision AI and sensor data. And this will also be helpful to the boss, right?"
"Hmm...?" Jun-ho turned his gaze to the confused Yun Yeong-su, and the latter confidently continued.
"If you fight in a place where the shelter drones or CCTVs can see you, it won't just shoot at moving objects. It will judge who is more threatening and where it's more efficient to shoot. Akina will calculate the optimal firing data in real-time and let you know."
Yun Yeong-su added with a smile like a villain behind the scenes, "It accumulates data and learns on its own every time it tests and operates, constantly improving its performance. Since the deep learning model updates in real-time, it might stutter a bit at first, but after a few runs, it processes things much faster and more accurately than a human. So, once you set it up and feed it enough data, you won't need to touch it one by one; it'll do everything on its own."
"So when will all that be done?"
"...Ah."
Stopped by Jun-ho's cold observation, Yun Yeong-su averted his eyes with a sheepish look and said, "One... two months? Or maybe three?"
"...!"
Jun-ho was startled. If what Yun Yeong-su was saying became reality, whether it took two months or three...
'I could just make one for sniping and use it.'
When a human judges and fires, the trajectory becomes unstable beyond a certain distance due to conditions like wind speed and direction, limiting the effective range to 180 meters. But if an AI controls the firing, 200 meters is certain, and depending on the situation, it might even extend by another 20 to 30 meters.
Of course, since the power was increased compared to what they were using now, the number of shots possible with a portable air tank would be less than 10, and the sound would be louder. But since it would be a sniping situation, he would be firing from quite far away, and with the drone's auxiliary perimeter surveillance, it wouldn't be a big problem.
Jun-ho was secretly happy, but since it wasn't common for the always-confident Yun Yeong-su to shrink away like this, he intentionally chuckled and said, "Yeong-su, focus on the turret and drone work and get it done."
"Yes..."
"Hahaha! Look at this guy. Hurry up and write the program, you punk."
"U.n.d.e.r.s.t.o.o.d. Tch, just you wait..."
Yun Yeong-su, whose pride was hurt in a strange way, recited the line that defeated villains always say when fleeing and walked sluggishly toward the main building where the control room was located.
***
Three more days passed. During that time, Baek Ha-il, with Choi Jeong-woo as his assistant and the help of the AI, worked late into the night to complete 10 dual-barrel T1 turrets first. Since the completed T1 turrets had no problems in the tests conducted at the underground shooting range, Jun-ho loaded the turrets onto the multi-purpose electric vehicle and went around the guard posts on the mountain behind the shelter with Choi Jeong-woo, installing them one by one.
"Boss, aren't you heavy?"
"Not really."
Choi Jeong-woo was shocked to see Jun-ho stride up the slope without a care, carrying a turret weighing over 20 kilograms and a 6-kilogram industrial oxygen tank at the same time. But now, as a full member of the shelter, he knew exactly what kind of person Jun-ho was. Unlike the first day, he looked at Jun-ho's back with a reassuring gaze, filled with pure admiration rather than fear.
His daughter, Choi Ji-woo, was beyond simply being safe; after eating her fill for breakfast, she was now learning from Baek Su-ah, who had attended a prestigious Seoul university pharmacy program, along with Kim Ha-yun and her brother.
He was greatly surprised to see that they had prepared not only personal tablets containing all the textbooks and reference books needed for the compulsory education curriculum, but also notebooks and writing utensils that would last dozens of people for several years—as if they had looted an entire stationery store. Furthermore, he couldn't help but click his tongue at the news that they had actually looted(?) a stationery store that was scheduled to close.
Moreover, the prospective sister-in-law(?), who was small in stature but had a bold impression, was taking care of his daughter and Kim Jun-seo by Baek Su-ah's side. Having grown up in an orphanage, she was a master at handling children like Ji-woo and Jun-seo. Honestly, he even thought she might be better than a daycare teacher.
Anyway, everything from eating to playing and learning—except for toddler clothing—was almost perfect, and Choi Jeong-woo was beyond satisfied; he was almost moved to tears.
'Jae-young... I don't have to worry about our Ji-woo anymore, you know.'
He felt melancholy at the sudden thought of his dead wife, but Choi Jeong-woo shook his head lightly, readjusted the bag containing the equipment, and followed Jun-ho up the mountain diligently.
In a world that had become hell... if his beloved daughter could continue to live in this heaven-like 'Our Shelter', he could do anything.
***
A day passed, and finally, Choi Ui-su and Kim Hui-yeong left the nursing home and came to the shelter. For the safety of the nursing home, Jun-ho provided one air rifle with an effective range of about 100 meters, which had lower power than the ones used at the shelter. This was because Go Seok-jin was a former Army Sergeant, Go Jeong-nam had experience hunting with shotguns and air rifles in his youth, and Lee Jae-seok was also a veteran, so they would have no trouble using the air rifle if they received proper training.
Anyway, the Han Ah-reum Nursing Home was equipped with one PTZ camera and four domestic wide-angle CCTVs, allowing them to check everything coming toward the nursing home within a radius of 800 meters during the day and 300 meters at night. In addition, by installing a repeater and simple communication equipment, they could contact the shelter's control room at any time, and the control room could also directly manage the nursing home's systems, including power, to some extent. It was a safety device in case looters or hostile forces ever occupied the place. Of course, he didn't tell them that part, but since it was obvious that Jun-ho was 'sincerely' supporting the nursing home, the people there were genuinely grateful to him.
Having turned the nursing home, which would have otherwise been burned to ruins, into the first forward base of Gahyeon-ri, Jun-ho brought these two people—Choi Ui-su, an Emergency Medicine specialist who had finished a minor in trauma surgery, and Kim Hui-yeong, a former head nurse who had worked in general hospitals for over 20 years, experiencing everything from internal medicine and surgery to pediatrics, obstetrics and gynecology, and the emergency room—to the container residential area as members of Our Shelter.
"You can stay here for about a week. It's a place to stay for adaptation before entering the shelter."
"Ah... I see."
The couple, who were surprised to see that the old, rusty iron gate at the entrance with several 'No Entry' signs was actually a state-of-the-art blast door, and were left with their mouths agape like Choi Jeong-woo in the past when they saw the long container blocking the road open to both sides like an automatic door, seemed to finally be relieved and fully trust Jun-ho once they entered and saw that there were over 10 container houses, and that despite their old-looking exterior, the interiors were well-decorated to the level of a fully-furnished studio apartment.
"Bedtime, wake-up time, and meal times are fixed. Basic groceries are in the refrigerator. Since over 10 people live together, minimal time discipline is necessary. And..."
As they nodded while listening to the shelter's rules and precautions Jun-ho explained, Choi Ui-su asked, "But, I understand what you expect from us, but medical practice has no choice but to have limits if equipment and facilities are not properly equipped. So, I was wondering..."
"What do you need?"
"...Yes?"
"Ah, first, I think it would be better to let you know what we have."
Jun-ho displayed the list of medical equipment and facilities he had purchased from the Volcano Group in the past on the tablet screen and said, "First, a defibrillator, ECG monitor, oxygen generator, and suction machine are ready. We have a full set of suture surgical equipment. We also have a medical sterilizer, sterile workbench, electric cautery, UV sterilizer, and surgical table. Just in case, we prepared two or three sets of everything."
"...!"
"As for diagnostic testing equipment... there are automatic blood pressure monitors, blood analyzers, fixed and portable X-ray equipment, and ultrasound diagnostic machines. There are IV sets, syringes, medicine refrigerators, and freezers. Of course, there are many basic medicines and professional drugs. You can search the list on the tablet."
"Ah, no..."
"My goodness. How did you prepare all that?"
To the shocked Choi Ui-su and Kim Hui-yeong, Jun-ho said calmly, "Well. And I told you. It would be the safest and best place to live in South Korea right now. Then this much should be prepared."
"Huh..."
"How on earth..."
The couple, who had expressions of disbelief, turned their heads at a sudden noise. They saw the container opposite the direction they had entered opening slowly. Jun-ho, who glanced in that direction, smiled and said, "It seems the kids from our shelter I told you about have come to play. Since they've stayed here for quite a long time, they seem to find this place comfortable."
The children and two dogs, who had been riding in the passenger seat and the rear cargo bed of the multi-purpose electric vehicle driven by Baek Su-ah, poured out, and the smallest girl ran excitedly through the yard with the black dog.
"Ji-woo! Choi Ji-woo! You'll fall if you do that!" Kim Ha-yun, who always followed and took care of the two children because she didn't know what might happen, raised her voice, even though it was safe because there were Ferdy and Kkamsuni, who were better than humans in some ways, and CCTVs everywhere.
"Oh my, how cute."
The couple smiled broadly, keeping their eyes on the innocent appearance of Choi Ji-woo. But soon, they saw Kim Jun-seo with a slightly dark expression following her, and the moment they saw the small-statured Kim Ha-yun walking quickly by the side of the slender Baek Su-ah.
"...!!!"
As if they had made a promise, their eyes widened, and "Yoo, Yu-na...?" Kim Hui-yeong called the name of her daughter who had died 6 years ago in a trembling voice, as if she couldn't believe it.