The Hawk's Eye Under the Sea 'Sona' ... Now in Our Hands

원본보기 아이콘

원본보기 아이콘

[Asia Economy Yang Nak-gyu, Military Specialist Reporter] During the Sewol Ferry disaster in 2014, the rescue ship Tongyeong was embroiled in controversy for not being deployed at the scene. Although it was supposed to be equipped with a SONAR to detect the enemy's location and distance, it was instead fitted with a civilian fishing vessel’s fish-finding sonar. The supplier who provided the civilian fishing vessel sonar to the military also delivered substandard equipment to a mine-hunting ship in 2016. Since there was no domestically developed SONAR technology, the military was helplessly outmaneuvered by arms dealers. On the 28th of last month, we visited Sonatech, the first company in Korea to develop SONAR technology.

Climbing up the foothills of Hwangnyeongsan Mountain in Nam-gu, Busan, a four-story building caught my eye. Entering the building, which resembled a university research center, the windows used on naval vessels were impressive. Researchers were deeply engaged in their work through the windows.

Park Seung-su, CEO of Sonatech, said, "This is where the first domestically developed underwater acoustic colorimeter (SONAR) is made," and led the reporter to the briefing room.

Underwater acoustic colorimeters are divided into two types: towed types that are dragged behind ships and hull-mounted types attached directly to the ship. The towed type is used to detect small objects underwater, while the hull-mounted type is used to detect fast-moving objects like submarines at long distances.

Watching sample footage captured by the towed underwater acoustic colorimeter, it looked like a 3D ultrasound scan of a pregnant woman’s womb, with unknown objects appearing on a yellow background. Upon closer inspection, it revealed various objects and environments such as sunken ships, drowning victims, and seabed topography. The submarine shown in the footage was an actual moment when a South Korean Navy submarine was submerged. According to the company, large underwater acoustic detectors can detect objects up to 1.4 km away.

CEO Park said, "Recently, we developed a SONAR with about ten times higher resolution that can detect objects as small as 3 cm, comparable to radars used on land."

The equipment that must be installed alongside the underwater acoustic colorimeter is the underwater temperature measuring device. The underwater acoustic colorimeter measures distance by sending sound waves and receiving their echoes. However, the speed of sound waves varies depending on the water temperature, causing errors in distance measurement. Therefore, the underwater temperature measuring device is installed to check the temperature at different depths and calculate accurate distances. This device was also first developed domestically by Sonatech.

Recently, Sonatech developed an integrated SONAR module for unmanned surface vehicles and unmanned submarines. This integrated device combines the functions of the underwater acoustic colorimeter and underwater cameras into one, with miniaturization as the core technology. Although it is only half the size of a regular underwater acoustic colorimeter, which inevitably reduces detection range and other functions, the company explains that it is sufficient for detecting and avoiding obstacles ahead.

The P-3C maritime patrol aircraft, known as the submarine killer of the Navy, uses "sonobuoys." Sonobuoys, a type of underwater acoustic colorimeter, are dropped into the sea to locate submarines. The P-3C is dispatched to detect submarines at long distances. Until now, sonobuoys have been developed by the US or UK and imported. However, after achieving domestic production last year, the South Korean military is expected to adopt domestically produced sonobuoys. The domestic sonobuoys cost about 70% of imported ones but have even better performance.

CEO Park led the reporter inside the building to show next-generation equipment. Inside was a water tank laboratory measuring 18 meters wide and 8 meters long. Visually, the water seemed less than 1 meter deep, resembling a swimming pool. However, the depth reached 10 meters, allowing for comprehensive testing of all equipment.

Park showed a helmet equipped with a camera. It was a SONAR that allowed divers to clearly see the environment ahead even in pitch-dark underwater conditions where visibility is zero. The camera had no lens and was blocked in front, resembling goggles, but the helmet revealed a new world. Like looking at a radar, the front distance, depth, temperature, diving time, and diver’s location were all visible at a glance. Especially through big data, it was easy to identify the nature of objects ahead in the dark underwater environment.

Park said, "The domestic development of SONAR was something that had to be accomplished by someone," adding, "We will serve as a map for the export market of defense small and medium enterprises that have been in the dark."

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