• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1913-1916
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• 1996

With a progress of electrical and electronic technology, radio-frequency circuits including high frequency components are widely applied to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of acetylene-air and ethylen-air mixtures experimentally based on the IEC 79-3 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a $10{\Omega}$, $20{\Omega}$, $30{\Omega}$, $40{\Omega}$ or $50{\Omega}$ resistor and a power amplifier with frequency range up to almost 1 MHz. Experimental results show that the ignition of the acetylene-air and ethylen-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit: the minimum ignition voltage increases gradually with the increase of the frequency.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.367-370
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• 2007

Recently, With explosive national land developments construction fields ate increasing, and slope failures are disastrous when they occur in mountainous area adjoining highways. but public institutions and supervisors, to manage slope need GIS for managing it more quickly and correctly. For manage slope, it is nesessary to use new IT, especially wireless internet. The current domestic population using cell phones exceeded 30 million and the domestic wireless Internet environment has matured, but implementation of mobile technology for government services isnot matured enough. In this paper the author proposed a new system of mobile PPT monitoring for managing slope inspection for Ubiquitous Environment. This new system manages data in real time and reduces human power when applied to current working environments. This research was supported by a grant(NEMA-06-NH-05) from the Natural Hazard Mitigation Research Group, National Emergency Management Agency.

• 정보학연구
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• 제8권1호
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• pp.11-25
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• 2005

The purposes of this study were to explain consumer attitude, expenses and satisfaction of mobile-phone Users. The data of this study used from Pollever.com. This study was satisfaction of mobile-phone users in Korea. The users were consumers of Samsung, LG, SK-Telecom and Pantack. The critical success factor was on the subside for mobile-phone in the growth of mobile service, which we can analyze in its positive effects. Fifty percent of consumers were unsatisfaction with local companies without Samsung. Now most of local mobile-companies will developed music-phone, high-tec camera-phone, hi-slim phone, and health-phone. But, the results of this study are as fallow: Most of consumer' main issues were design, weight, and brand power. It was in that it played the driving force to upgrade the local mobile-phone services into international level with the explosive growth in business by providing cheap phones.

• 한국항공운항학회지
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• 제25권3호
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• pp.135-142
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• 2017

As PED(Personal Electronic Device) market has been rapidly grown, the demand on Lithium battery, which is most commonly used power source of PED, also has been increased. Dew to this trend, the amount of Lithium battery air transportation is also increasing. However, it should be treated very carefully because Lithium is one of very explosive metal. So ICAO, IATA and civil aviation agencies try to enhance the safety of Lithium battery air transportation by aircraft certification and operating regulations. To enhance in-flight safety, the aircraft for transporting Lithium battery should equip certified fire extinguishing system. But recent studies find that Halon, currently used extinguishing agent, is not effective on extinguishing Lithium battery fire. Besides, there is no certified Halon replacement for air use and no acceptable specific minimum performance standard(MPS) for Lithium battery fire. For this issue, a study on characteristics and establishing MPS of Lithium battery fire is needed for safe air transportation of Lithium battery.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.407-410
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• 2002

A series of steam explosion experiments using real core materials of $ZrO_2$ and corium(a mixture of $ZrO_{2}\;and\;UO_{2}$) has been performed to evaluate the risk of steam explosion load in nuclear power plants. Surprisingly, spontaneous steam explosions are observed far both materials, which have been thought to be inexplosive so far. The dynamic pressure and morphology of the debris clearly indicate the evidence of an explosion. The experimental results also indicate that $ZrO_2$ is more explosive than corium.

• 항공우주시스템공학회지
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• 제10권1호
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• pp.118-126
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• 2016

North Korea has continued developing ballistic missiles with various ranges. Even through the recent launch long-range missiles, it can be inferred that North Korea's Missile technology has reached a level where it can even threaten the US. moreover, through the three times nuclear tests, North Korea is known to have succeeded at gaining 10~20KT of explosive power as well as the minimization and lightening of nuclear warhead. Considering the short length of war zone in Korean peninsula and the possibility of nuclear equipment, if be the most severe threat across the whole peninsula. Since the midcourse phase flight takes the longest time, ROK should establish the ability to intercept at this middle phase. From this perspective, this paper describes mission effect of a sea-based BMD system through empirical threat and flight characteristic analysis using MIT model that was not suggested in original research.

• 한국웰니스학회지
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• 제7권2호
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• pp.101-111
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• 2012

The benefits and risks of whole body vibration (WBV) based acceleration training on the human body have been documented for many years. WBV training has been shown to increase muscular strength, explosive power, bone strength, performance, mobility, cardiovascular function, circulation and anabolic hormone level and so on. The purpose of this review is correct understanding and application of WBV training. Without proper understanding, rather, to apply WBV to the human body can be fatal harm, and therefore know that what is vibration and has advantages and disadvantages. If there is anything positive side there is bound to the negative aspects. In this regard, WBV training can have a positive impact on the already confirmed by several studies and also, there have been scientifically proven. But still we are part of a scientific approach that is acceptable even to keep in mind that you will always coexist. Once again, the effect of WBV with a physical stimulus that risk and should be remembered. In addition, given the momentum and how to exercise and well-being well aware that vibration exercise as a way to think of how not to be familiar with.

• 한국항공우주학회지
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• 제42권5호
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• pp.430-436
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• 2014

본 논문에서 제안한 우주기반기술 검증용 극초소형 위성의 명칭은 STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project)이며, 주요임무는 가변 방사율 열제어기, 형상기억합금 진동 절연기, 진동형 히트파이프, MEMS 기반 고체 추력기와 같이 국내 산학연에서 기 수행된 우주핵심기술을 발굴 및 탑재하여 궤도검증을 실시하는 것이다. 또한, 배열형 집광렌즈가 적용된 고효율 집광형 태양전력시스템과 열선절단방식이 적용되어 높은 체결력과 적용방법에 따라 복수구조물의 구속 및 분리가 가능한 무충격 구속분리장치를 주요 탑재체로 개발하여 궤도 검증을 실시예정이다. 본 논문에서는 상기 탑재체의 궤도 검증을 임무목적으로 하는 STEP Cube Lab.의 체계 및 부체계 개념설계를 통해 임무의 구현 가능성을 검토하였다.

• 에너지공학
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• 제23권2호
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• pp.149-157
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• 2014

원자력발전소의 증기발생기 전열관은 가동 중에 다양한 형태의 부식 손상이 발생한다. 전열관의 외면에 발생하는 응력부식균열은 2차측 응력부식균열이라 불리는데 주로 전열관의 확관천이지역에서 발생한다. 그 원인은 이 지역의 기하학적 특성과 관련된 슬러지의 침적에 의한 불순물의 농축과 증기 발생기 제작과정에서 확관에 의한 잔류응력이다. 특히 잔류응력은 확관방법에 따라 방향성 및 그 크기가 달라지는데 전열관에 발생하는 균열의 방향 및 발생빈도는 이와 관련이 있다. 현장 경험에 따르면, 폭발확관된 전열관은 수압확관된 전열관에 비해 확관천이 부위에서 원주방향 균열이 잘 발생하는 것으로 나타났다. 따라서 본 연구에서는 예민화된 증기발생기 전열관에 대한 응력부식균열 시험을 통해 확관법에 따른 특정방향 균열의 발생빈도 및 균열 크기를 비교하였다. 또한 균열이 발생된 전열관의 파단면 검사를 통해 균열 양상과 수화학 환경 중의 특정 성분의 영향을 관찰하였다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제3권11호
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• pp.393-402
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• 2014

최근 스마트폰을 포함한 사물 인터넷(IoT) 기술 기반의 스마트 기기의 급속한 확산에 따라 IEEE 802.11 무선 랜에서 전력 소비 또한 급격히 증가하고 있다. 특히 모바일 기기 사용자가 급격하게 증가하면서 가정이나 사무실 같은 실내 환경에서 사설 무선 AP(Access Point) 설치가 급증하고 있는 추세이다. 본 논문은 현재 무선 AP의 비효율적인 운영을 개선한 무선 AP의 전력 소비 절감 알고리즘을 제안한다. 제안한 알고리즘 동작은 STA(Station)의 무선 AP 접속 여부에 따라 구분되며, STA가 있을 경우는 STA로 전송할 데이터가 있을 때와 없을 때로 나뉜다. STA가 없는 경우, 수면 모드로 동작하여 불필요한 전력 소비를 최소화한다. 또한 추가적으로 STA가 접속을 하고 있는 경우에도 데이터를 수신하지 않을 경우에는 인증 및 결합이 유지된 상태로 수면 모드를 운영한다. STA로부터 데이터 요청이 있을 경우 STA의 거리와 전송률을 파악하여 STA의 전송률을 만족하는 최소의 송출 전력으로 패킷을 전송한다. 이때, STA와 최초로 스캔 과정을 하는 데 필요한 관리 프레임은 최대 송출 전력으로 전송한다. 본 논문에서 제시한 시나리오를 바탕으로 제안한 전력 소비 절감 알고리즘이 적용된 무선 AP에서의 전력 소비량은 기존 방안이 적용된 무선 AP와 비교하면 약 18%, 전력 소비 절감이 적용되지 않은 일반적인 무선 AP와 비교하면 약 35% 감소했다.