• Journal of the Korean Institute of Gas
• /
• v.26 no.1
• /
• pp.1-6
• /
• 2022

This paper is a purpose to study and analyze the engine starting failure examples for LPG car. The first example, the researcher verified the phenomenon that didn't supply the fuel because of filter clogging by fine alien substance in the gas valve line when he inspected the emergency cutting valve. The second example, there was no the influence of gas leakage when the solenoid operated at first. But the damage part of solenoid assemblying face wad downed a durability according to running a valve. Eventually, the researcher checked on the phenomenon of engine stopping by no gas feeding in solenoid because of leaking of gas. The third example, the researcher sought that the wiring sheaths of connector fin between EGR 10A fuse and LPG switch verified the burn-out phenomenon due to the bad contacting as tension damage produced the overheating. Therefore, the manager of a car has to do pre-inspection no producing electric failure and he must maintain his car with optimum condition.

• Maritime Security
• /
• v.6 no.1
• /
• pp.109-135
• /
• 2023

The North Korean military's maneuver toward Honam was the fastest maneuver the North Korean army had demonstrated during the Korean War, and it was a threatening attack that forced the Korean and Allied forces to fully adjust the defenses of the Nakdong River. However, when this study analyzed the North Korean military's maneuver toward Honam in terms of indirect approach strategy, there were a number of factors that inevitably led to its failure. In terms of implementing the indirect approach strategy, the North Korean military cited a number of failure factors, including the dispersion of combat forces, the inflexibility of changing the line of operation, the maneuvering of ground forces, and the lack of psychological distaction. However, the North Koreans were preparing for a final "surprise attack," in which the 7th Division, which was following the North Korean 6th Division, took another diversion and attempted to attack in the direction of Tongyeong. With this, the North Koreans intended to break through the Nakdong River defenses and head for Pusan. However, the North Korean attack was ultimately thwarted by the Korean Navy and Marine Corps' Tongyeong Amphibious Operation. With a swift maneuver using the sea as a maneuvering space, the Navy and Marine Corps occupied key points first, creating an advantageous situation and fending off an attack by the North Korean 7th Division. The Navy and Marine Corps' Tongyeong Amphibious Operation finally thwarted the North Korean military's maneuver toward Honam, thus maintaining the Nakdong River defenses.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1371-1374
• /
• 1995

It is well known that the degradation of transformer oil conseqently lead to the failure of transformer. This paper discussed the characteristics of the degradation sensor checking transformer oil condition in live line. The degadation sensor is composed of base ring, electrodes and porous ceramic, passed through the transformer oil and checks the transformer oil condition through sensor's leakage current. So it is important to minimize the leakage current of base ring and connection parts. To investigate the leakage current of base ring and connection parts the characteristics of V-T-I and DC 2 KV and other examinations were performed. It is verified that ionized transformer oil caused by the expansion of temperature increases in the leakage current of porous ceramic sensor. It is certification that the leakage current of other parts of porous ceramic is very small(about 2%) compared with the porous ceramic body and it is confirmed that the leakage current in porous ceramic is changed sensitively according to the new oil(NO) and and the degradation oil(DO).

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.12 no.1
• /
• pp.72-81
• /
• 1990

Because failure of microvascular flap grafting has sometimes been attributed to vascular obstruction in the anastomotic site, this study investigated the healing process after microvascular anastomoses. The healing process of anastomotic sites were observed by the use of the light and the scanning electron microscope after microvascular anastomoses of the right common carotid artery in rats. The experimental animals were sacrificed on the 4th day, 1st, 2nd, 4th and 6th week. Throughout the whole experimental period, arterial patency rate was 78% (11/14). At the early stage, it was possible to recognize histologically disappearance of endothelial cell and rupture of part of the media. Subintimal hyperplasia and the growth of media appeared around the suture line at the 2nd week. Endothelial cell regeneration occurred and the depth of vessel wall was normalized at the 4th week. By the scanning electron microscope, at the early stage, the anastomotic site was covered with many platelets, red blood cells, fibrins and macrophages. At the 4th week, the insertion site of the thread was completely covered with normal endothelial cells which were parallel to longitudinal axis of vessels and complete reendothelialization over the anastomotic site seemed to take about 6th week.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.14-21
• /
• 2011

Reliability means that a product maintains its initial quality and performance at certain period of time(time, distance, cycle etc) under given condition without failure. Given conditions include both environmental condition and operating condition. Environmental condition means common natural environment such as temperature, humidity, vibration, and working condition means artificial environment such as voltage, current load, install place, hours of use, which occurs during using the product. In the field of railway vehicles, although components of railway vehicles with reliability are the trend of mandatory as persisting period of railway vehicles is extended, using components of railway vehicles is insufficient for the practical reliability assessment. but the meaning of the first railway operating agnecy to acquire the parts in the field, the data suggest the reliability of products if you can and can show the reliability of modular units and modular units can provide the reliability of if you can present reliability of the entire system is thought to be here. In this study, lifespan of micro-switch for master controller is analyzed and prediction is performed based on its field data considering the special circumstances of railway vehicles operating agency, such as a large number of trains operates on the same line.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.4
• /
• pp.584-590
• /
• 2013

Depending on the operating characteristics, track circuit is installed for the purpose of control directly or indirectly of the signal device, point switch machine and other security device. These are mainly used for train detection, transmission of information, broken train detection and transmission of return current. Especially, the return current is related to signal system, power system and catenary line, and track circuit systems. It is one of the most important component shall be dealt for the safety of track side staff and for the protection of railway-related electrical system according to electrification. Therefore, an accurate analysis of the return current is needed to prevent the return current unbalance and the system induced disorder and failure due to an over current condition. Also, if the malfunction occurred by the return current harmonics, it can cause problems including train operation interruption. In this paper, we presented measurement and analysis method at return current and it's harmonics by train operation. By the test criteria, we evaluated for safety. Hereafter, it is expected to contribute to the field associated with it.

• Journal of Korea Multimedia Society
• /
• v.15 no.12
• /
• pp.1464-1474
• /
• 2012

In this paper, we propose a QoS (Quality of Service)-aware and cooperative resource reservation scheme using cross-layer link adaptation for wireless high definition video transmission through UWB (Ultra Wide Band) network with D-MAC (Distributed Medium Access Control). A wireless high definition video transmission system usually requires stable high throughput even without line-of-sight, e.g., a destination device in another room separated by a wall. Since the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme causes lots of DRP resource reservation conflicts due to failure of beacon detection in wireless channel environment, overall performances of the WiMedia D-MAC can be deteriorated. And the current WiMedia MAC standard has not considered QoS provisioning even though QoS parameters such as a range of service rates are provided to each traffic stream. Therefore, we propose Relay DRP protocol with QoS-based relay node selection criterion, which makes a relay path to avoid DRP resource reservation conflicts and guarantee QoS more stably through cross-layer link adaptation of cooperative relay transmission scheme and is compliant with the current WiMedia D-MAC protocol. Simulation results demonstrate performance improvements of the proposed method for throughput and QoS provisioning.

• The Journal of Engineering Geology
• /
• v.24 no.2
• /
• pp.191-199
• /
• 2014

We describe a method for detecting slope instability in flume tests using pore pressure and water content data in conjunction with a statistical control chart analysis. Specifically, we conducted univariate statistical analysis on x-MR control chart data (pore pressure and water content) collected at several points along the flume slope, which we separated into three parts: upper, middle, and lower. To assess our results in the context of landslide forecasting and warning systems, we applied control limit lines at $1{\sigma}$, $2{\sigma}$, and $3{\sigma}$ levels of uncertainty. In doing so, we observed that dispersion time varies depending on the control limit line used. Moreover, the detection of instabilities is highly dependent on the position and type of sensor. Our findings indicate that different characteristics of the data on various factors predict slope failure differently and these characteristics can be identified by univariate statistical analysis. Therefore, we suggest that a univariate statistical approach is an effective method for the early detection of slope instability.

• Journal of the Korean Society of Safety
• /
• v.28 no.2
• /
• pp.21-25
• /
• 2013

The purpose of this study is to provide basic data for the safety assessment of a water purifier when water leaks due to inappropriate maintenance and the examination of the cause of accidents related to the leak. Due to its inspection and management by non-specialists, if a leak occurs in a water purifier with the water level controller being inclined, it may result in the failure of the compressor, power supply line, PCB, etc. The analysis of the thermal diffusion pattern of water purifier compressors using a thermal image camera shows that its maximum temperature was approximately $80^{\circ}C$. In addition, its operating current was a maximum of 13 A and the system's operating current was approximately 1.7 A after the compressor was charged. It was found that the housing type power cable cover of the compressor had the effect of preventing electric shock but has poor flame resistance. Furthermore, the performance of the overload protector, PTC relays, etc., was excellent but they have potential for problems as metallic terminals were exposed, resulting in the potential of a safety related accident. The terminals and their surface damaged by the tracking showed a trace of carbonization and the resistance between terminals was measured to be approximately $8{\Omega}$. In addition, while the tracking was proceeding, the fuse and circuit breaker installed for system protection did not operate.

• Journal of Energy Engineering
• /
• v.22 no.4
• /
• pp.327-332
• /
• 2013

일본 연구에서는 열충격 시험을 통한 태양전지의 파괴모드에 따른 전기적 특성을 분석하였다. 시편은 Photovoltaic Module을 만들기 전 3 line Ribbon을 Tabbing한 단결정 Solar Cell을 제작하였다. 열충격 시험 Test 1의 온도조건은 저온 $-40^{\circ}C$, 고온 $85^{\circ}C$, Test 2는 저온 $-40^{\circ}C$, 고온 $120^{\circ}C$에서 Ramping Time을 포함하여 각각 15분씩, 총 30분을 1사이클로 500사이클을 각각의 조건으로 수행하였다. 열충격 시험 후 Test 1에서는 4.0%의 효율 감소율과 1.5%의 Fill Factor 감소율을 확인하였으며, Test 2에서는 24.5%의 효율 감소율과 11.8%의 Fill Factor 감소율을 확인하였다. EL(Electroluminescence)촬영 및 단면을 분석한 결과, Test 1과 Test 2 시편 모두 Cell 표면 및 내부에서의 Crack이 발견되었다. 하지만, Test 2의 시험이 Test 1보다 가혹한 온도조건의 시험으로 인해 Test 1에서 나타나지 않았던, Cell 파괴를 Test 2에서 확인하였다. 결국, Test 1에서 효율의 직접적인 감소 원인은 Cell 내부에서의 Crack이며, Test 2에서는 Cell 내부에서의 Crack 및 Cell 파괴로 인한 Cell 자체의 성능저하로 효율이 크게 감소한다는 것을 본 실험을 통하여 규명하였다.