• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.7
• /
• pp.662-669
• /
• 2017

Military rotary aircraft are heavily exposed to projectile environments due to their mission characteristics, and fires caused by fuel leaks after shooting are linked directly to the loss of human life. To improve the survivability of pilots and crews, the fuel tank in rotary aircraft must have gunfire resistance and anti-explosion characteristics. Gunfire resistance can be satisfied by applying a self-sealing cell to a fuel tank. Anti-explosion can be satisfied by reducing the oxygen concentration in an explosive area and suppressing the generation of combustible fuel vapor by minimizing the evaporation rate of the fuel by heat. A Korean utility helicopter applies anon-board inert gas generation system to meet the anti-explosion requirements for ballistic impact. The generator fills the fuel tank with an inert gas and reduces the oxygen concentration. This paper describes the overall development process of the OBIGGS developed in accordance with the localization process of weapon components. OBIGGS was developed/manufactured through domestic technology, and the performance was found to be equal to or better than that of the existing products through single performance tests and aircraft mounting tests.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.6
• /
• pp.2739-2746
• /
• 2011

This paper proposes the method for more effectively calculating X/R which is the ratio of equivalent reactance(X) and resistance(R) of the bulk power system and analyses the characteristic of X/R values by applying the proposed method to the real bulk power systems. X/R is used to determine the rating of the relay in the bulk power systems and its value has been accepted to be big enough to ignore the equivalent resistance of the bulk power systems. However, X/R is calculated as a big number when only the upper transformer and transmission line are considered. The correct approach to calculating X/R needs to consider all the parameters including generators, transformers, lines and loads. This paper calculates X/R of the bulk power systems using dynamic models which have been used to analyse the power system stability. The effectiveness of the proposed method is verified by applying it to the test system and X/R values of the real bulk power systems are analyzed. In addition, the dependence of X/R on the closeness of its calculating locations to the generator is verified by using the marginal loss factor which has been used in the electricity market.

• Radiation Oncology Journal
• /
• v.5 no.1
• /
• pp.49-58
• /
• 1987

Hypertermia for the treatment of cancer has been introduced for a long time and the biological effect for the use of hyperthermia to treat malignant tumors has been well established and encouraging clinical results have been obserbed. Unfortunately, however, the engineering or technical aspects of hyperthermia for the deep seated tumors has not been satisfactory. We developed the radiofrequency capactive hyperthermia device (Greenytherm-GY8) in cooperation with Yonsei Cancer Center and Green Cross Medical Corporation. It was composed with $8{\sim}10MHz$ RF generator, capacitive electrode, matching system, cooling system, temperature measuring system and control PC computer. The thermal profile was investigated in agar phantom, animals and in human tumors, heated with capactivie RF device. Deep and homogeneous heating could be achieved in a large phantom of 25cm diameter and 19cm thick when heated with a pair of 23cm diameter electrodes, coupled to both bases of the phantom, when the size of the two electrodes was not the same, the region near the smaller electrode was preferentially heated. It was, therefore, possible to control the depth of heating by choosing proper size of electrodes. Therapeutic temperature $(42^{\circ}C{\sim}43^{\circ}C)$ could be obtained in the living animal experiments. Indications are that deep heating of humn tumors might be achieved with the capacitive method, provided that subcutaenous fat layer is cooled by temperature controlled bolus and large size of electrodes.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.36C no.10
• /
• pp.17-28
• /
• 1999

In this paper, an ASIC emulation system called ACE (ASIC Emulator) is proposed. It can produce the prototype of target ASIC in a short time and verify the function of ASIC circuit immediately The ACE is consist of emulation software in which there are EDIF reader, library translator, technology mapper, circuit partitioner and LDF generator and emulation hardware including emulation board and logic analyzer. Technology mapping is consist of three steps such as circuit partitioning and extraction of logic function, minimization of logic function and grouping of logic function. During those procedures, the number of basic logic blocks and maximum levels are minimized by making the output to be assigned in a same block sharing product-terms and input variables as much as possible. Circuit partitioner obtain chip-level netlists satisfying some constraints on routing structure of emulation board as well as the architecture of FPGA chip. A new partitioning algorithm whose objective function is the minimization of the number of interconnections among FPGA chips and among group of FPGA chips is proposed. The routing structure of emulation board take the advantage of complete graph and partial crossbar structure in order to minimize the interconnection delay between FPGA chips regardless of circuit size. logic analyzer display the waveform of probing signal on PC monitor that is designated by user. In order to evaluate the performance of the proposed emulation system, video Quad-splitter, one of the commercial ASIC, is implemented on the emulation board. Experimental results show that it is operated in the real time of 14.3MHz and functioned perfectly.

• Journal of the Korean Society of Radiology
• /
• v.11 no.7
• /
• pp.571-578
• /
• 2017

Bubbles are generated by the boiling of the cooling water when an accident occurs in the reactor and then in order to measure the void fraction, the Optical Fiber Probe(OFP) and optical camera are used in thermal hydraulic safety research. However, such an optical method is not suitable for measuring the void fraction in a $17{\times}17$ array of fuel rods due to the geometrical limitations. This study was conducted as a preliminary study using x-ray system and various phantoms before applying to rod bundles. Through radiographic and tomographic experiments, the tube voltage of the x-ray generator was 130 kVp and the tube current was 1 mA. In addition, it is possible to measure the hole of 1mm in size visually through the bubble resolution phantom, and it is confirmed that the contrast is relatively decreased in the inside of the freon in the case of the contrast evaluation using the road phantom. However, we could obtain good image without distortion when reconstructing the image. Bubble generation phantom experiments were used to confirm the flow direction of the bubbles and to acquire tomography images. The image J tool was used to measure the void fraction of 18 % for a single tomography image. This study has carried out previous researches for the measurement of the bubble rate around the nuclear fuel and could be used as a basic research for continuous research.

• The KIPS Transactions:PartC
• /
• v.11C no.3
• /
• pp.395-400
• /
• 2004

Being aware of growing needs for wireless communication led to the development of UWB systems, this study proposed an impulse for single band UWB systems which does not count a carrier; analyzed the characteristics and the problems of pulses suggested by the existing poise of the Un system; finally, proposed TDMG(Time Delay Multiple Gaussian) pulse that generates signals of UWB without attenuation of pulse width. The hardware structure of the TDMC pulse for the single band UWB system was modelled after describing the pulse in a mathematical method in an attempt to compare with performances of the existing pulses through computer simulation. The outcome of the test unveiled the fact that each center frequency of the TDMG pulse rose approximately 1GHz, and also each l0dB fractional bandwidth of the TDMG pulse was widened over 1GHz. In the case of derivative, center frequencies of the TDMG pulse rose over 1GHz each. As a consequence, the TDMG pulse appeared to have better quality frequency, satisfying the characteristics of spectrum and the band of frequency recommended by the FCC and decreasing interference with other wireless communication systems.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.328-334
• /
• 2020

At the recent practice test of the Remote Controlled Munition system (for practice), nine out of 125 samples were generated. Although 7.2 % misfires occurred, the acceptance test met the defense standards. Minimizing the probability of broken fuses is essential to reducing the number of samples and improving the AQL according to the process quality. In addition, it is necessary to increase military training and ensure user safety. In the case of practical grenades, hit-type detonators are applied. Unlike the normal design, which takes a hit by strikers, a different design of a hit by pressure from a pressure generator was used. This study analyzed the detonator surface through computational fluid dynamics. The results showed that the probability of functional weakness and retraction increased with increasing slope of the detonator surface. To overcome this, design changes were made to improve the fuse crimping process and increase the detonator holder seat. A performance test with the same number of samples from the whole quantity was operated. The probability of broken fuses was 0 %. Therefore, the reliability and performance of the ammunition can be improved and is expected to contribute to the drawing and process design when developing similar ammunition.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.6
• /
• pp.504-509
• /
• 2016

Defects in dissimilar metal welds are reported to be on the increase during the operating lifespan and aging of nuclear power plants. In Korea, reported cases of defects due to dissimilar metal welds include the drain nozzle of a steam generator and RCS hot tube sampling nozzles. Therefore, there is an urgent need to develop a reliable automated nondestructive inspection technique and a system for the inspection of dissimilar metal welds of small diameter nozzles in a high radiation area of a nuclear power plant. In this study, to ensure effective defect inspection of small diameter nozzles (RCS high-temperature tube sampling nozzle) of a nuclear power plant, three different methods were developed. These include: (1) optimum inspection probe design by beam simulation, (2) multi-directions UT optimum inspection technique for the inspection of small diameters of different welded parts, and (3) remote control automatic inspection system. The developed technique and systems have been verified to be suitable for use in the inspection of defects in smaller diameter nozzles in nuclear power plants.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.11 no.5
• /
• pp.623-629
• /
• 2018

Smart Factory is a concept of automatic production system of machines by the fusion of ICT and manufacturing. As a base technology for realizing such a smart factory, there is an increasing interest in a low-power environmentally friendly LED lighting system, and researches on so-called optical ID related application technologies such as communication using a LED and position recognition are actively underway. In this paper, We have proposed a system that can reliably identify logistics location and additional information without being affected by electromagnetic interference such as high voltage, high current, and generator in the plant. Through the basic experiment, we confirmed the applicability of the color ID recognition rate from 98.8% to 93.8% according to the eight color variations in the short distance.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.139-139
• /
• 2010

금속 실리사이드 나노입자는 열적 및 화학적 안정성이 뛰어나고, 절연막내에 일함수 차이에 따라 깊은 양자 우물구조가 형성되어 비휘발성 메모리 소자를 제작할 수 있다. 그러나 단일 $SiO_2$ 절연막을 사용하였을 경우 저장된 전하의 정보 저장능력 및 쓰기/지우기 시간을 향상시키는 데 물리적 두께에 따른 제한이 따른다. 본 연구에서는 터널장벽 엔지니어링을 통하여 물리적인 두께는 단일 $SiO_2$ 보다는 두꺼우나 쓰기/지우기 동작을 위하여 인가되는 전기장에 의하여 상대적으로 전자가 느끼는 상대적인 터널 절연막 두께를 감소시키는 방법으로 동작속도를 향상 시킨 $SiO_2/Si_3N_4/SiO_2$ 및 $Si_3N_4/SiO_2/Si_3N_4$ 터널 절연막을 사용한 금속 실리사이드 나노입자 비휘발성 메모리를 제조하였다. 제조방법은 우선 p-type 실리콘 웨이퍼 위에 100 nm 두께로 증착된 Poly-Si 층을 형성 한 이후 소스와 드레인 영역을 리소그래피 방법으로 형성시켜 트랜지스터의 채널을 형성한 이후 그 상부에 $SiO_2/Si_3N_4/SiO_2$ (2 nm/ 2 nm/ 3 nm) 및 $Si_3N_4/SiO_2/Si_3N_4$ (2 nm/ 3 nm/ 3 nm)를 화학적 증기 증착(chemical vapor deposition)방법으로 형성 시킨 이후, direct current magnetron sputtering 방법을 이용하여 2~5 nm 두께의 $WSi_2$ 및 $TiSi_2$ 박막을 증착하였으며, 나노입자 형성을 위하여 rapid thermal annealing(RTA) system을 이용하여 $800{\sim}1000^{\circ}C$에서 질소($N_2$) 분위기로 1~5분 동안 열처리를 하였다. 이후 radio frequency magnetron sputtering을 이용하여 $SiO_2$ control oxide layer를 30 nm로 증착한 후, RTA system을 이용하여 $900^{\circ}C$에서 30초 동안 $N_2$ 분위기에서 후 열처리를 하였다. 마지막으로 thermal evaporator system을 이용하여 Al 전극을 200 nm 증착한 이후 리소그래피와 식각 공정을 통하여 채널 폭/길이 $2{\sim}5{\mu}m$인 비휘발성 메모리 소자를 제작하였다. 제작된 비휘발성 메모리 소자는 HP 4156A semiconductor parameter analyzer와 Agilent 81101A pulse generator를 이용하여 전기적 특성을 확인 하였으며, 측정 온도를 $25^{\circ}C$, $85^{\circ}C$, $125^{\circ}C$로 변화시켜가며 제작된 비휘발성 메모리 소자의 열적 안정성에 관하여 연구하였다.