• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.1
• /
• pp.39-45
• /
• 2012

Currently, the aircraft industry, aircraft parts as well as airframe have been developed in producing, the aircraft parts and fuselages have been produced the product by cutting rather than forging and casting because of the residual stress and stress concentration. In this study, the aircraft is being used in many parts of aluminium alloy 2024 in wire-cut E.D.M. The selected experimental parameters are peak current, no-load voltage, off time and feed rate. It is found that cutting mountain part on surface roughness of the curve 0.3mm than 0.25mm diameter wire electrode is stable in many uniform distribution.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.14-18
• /
• 1996

From the experimental study of Wire-Cut EDM of die-material(SKD-11), machining characteristics such as machining rate, surface roughness and hardness have been observed and evaluated under the conditions varing pulse on time, pulse off time, peak voltage after fixing other conditions. It was found that various operating conditions have significant influences on machining rate, surface roughness. Hardness of workpiece was unaffected by operating conditions.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1996.06a
• /
• pp.69-75
• /
• 1996

40-100m 수심에 평탄한 모래층으로 구성된 구성된 친해를 1/1,000모형으로 축소시킨 무향수조내에서 Pekeris 모델에 대한 normal mode 관측실험을 점수신기로 수행하였다. 무향수조에 사용된 쐐기형 흡음재가 50kHz이상에서 20-25dB의 반향음 감쇠율을 가지므로 해서 이 수조가 해양과 유사한 조건을 갖게 되었으며, 실험에 사용된 점수신기는 B&K의 8130 수중청음기에 음향중심으로부터 조그만 크기의 사각형 틈을 제외하고 pressure-release 물질을 씌움으로써 얻을 수 있었다. 이 실험을 통해 얻은 결과들을 종합해 보면 연속모드의 피적분함수가 cut-off로부터 멀어지면 불연속모드의 합으로만 된 이론식과는 대략 수심의 10배 이내에서 다소 차이를 보일 뿐 전 관측거리에서 실험결과와 비교적 잘 일치하고 있다. 그러나 연속모드의 공진이 cut-off에 가까워 질수록 가상모드가 음향에 미치는 역할이 증대되어 근거리에서는 불연속모드의 합으로만 된 이론식과 큰 차이가 날 뿐만 아니라 영향이 미치는 거리가 수심의 수십배까지 증가함을 볼 수 있다. 특히 불연속모드의 개수가 2개이고 cut-off로부터 아주 가까운 가상모드가 존재할 경우, 가상모드가 수심의 60배 가까운 거리까지 영향을 미치는 것을 확인할 수 있다.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.5
• /
• pp.101-106
• /
• 2008

In the wire cut electrical discharge machining, the optimal machining parameters setting satisfying the requirements of both high efficiency and good quality is very difficult because its process involves a series of complex physical phenomena and the machining parameters are numerous over diverse range. In this paper, the experimental investigation has been performed to find out the influence of the machining parameters on the machining performance such as cutting speed and surface roughness. The selected experimental parameters are no load voltage, discharge peak current and pulse-off time. The experimental results give the guideline for selecting suitable machining parameters.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.249-254
• /
• 1998

This paper describes the control methods to cut out the NFB(No Fuse Breaker) of shorted load in the auxiliary power supply, Generally, when the short-circuit occurs in the load of the auxiliary power supply, the auxiliary power supply stops the operation according to the protection sequence. Finally, the other auxiliary power supply stops the operation by the same fault, To resolve this problem, we suggest the control method to trip the NFB of shorted load. That is, when the short circuit occurs, the controller changes control mode from voltage mode to current mode without the operation of output contactor(SIVK) in the auxiliary power supply. The auxiliary power supply provides a large current for the short-circuit load. After some time, the NFB of the short-circuit load is cut off and the auxiliary power supply Provides stable voltage for the loads except for the short-circuit load.

• Economic and Environmental Geology
• /
• v.44 no.4
• /
• pp.313-320
• /
• 2011

The Taebaegsan Mineralized District is the most prospective region for the useful mineral commodities such as a coal, non-metallic, metallic mineral in South Korea. From a general point of view, Cambro- Ordovician limestone formations, Myobong slate and Pungchon (Daegi) limestone, are the most fertilizable formations in the Taebaegsan Mineralized District. The geology around Weondong mine area consists mainly of Carboniferous-Triassic formations and Cambro-Ordovician formations intruded by rhyolite/quartz porphyry. The great overthrusted fault of N40~$50^{\circ}E$ direction, so called Weondong overthrust fault, is observed in the central part of the mine area and the NS fault system cuts the overthrusted fault. By postulating from the favorable geological and structural condition around Weondong area, the possibility of deep seated hidden ore bodies is expected. In 2010, on the basis of the results of LOTEM and CSAMT survey, the cross-hole survey was performed for the investigation of the hidden polymetallic ore body in the deep parts of the Weondong mine area and the grade of the newly-discovered orebody is as follows; (1) The cut-off grade for lead-zinc 3%; an weighted average grade 5.50% (2.7 m), (2) The cutoff grade for copper 0.1%; an weighted average grade 0.91% (14.65 m), (3) The cut-off grade for iron 30%; an weighted average grade 38.18% (3.3 m), (4) $WO_3$ for each cut-off grade(0.01%, 0.05%, 0.1%); an weighted average grade 0.29 wt. % (8.8 m), 1.15 wt. % (2.1 m), 1.97 wt. % (1.2 m), (5) $MoS_2$ for each cut-off grade(0.01%, 0.1%); an weighted average grade 0.15 wt. % (6.3S m), 0.28 wt. % (3.15 m), (6) $Ta_2O_5$ for each cut-off grade (0.01%, 0.1%); an weighted average grade 0.13% (19.S m), 1.11% (1.8 m), (7) $Nb_2O_5$ for each cut-offgrade (0.01%, 0.1%); an weighted average grade 0.06% 11.5 m), 0.15% (3.0 m).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.3
• /
• pp.61-69
• /
• 2002

To meet stringent LEV and ULEV emission standards, a considerable amount of development work was necessary to ensure suitable efficiency and durability of catalyst systems. The main challenge is to cut off the engine cold-start emissions. It is known that up to 80% of the total hydrocarbons(THC) are exhausted within the first five minutes in case of US FTP 75 cycle. Close-Coupled Catalyst(CCC) provides fast light-off temperature by utilizing the energy in the exhaust gas. However, if some malfunction occurred at engine operation and the catalyst temperature exceeds 1050$\^{C}$, the catalytic converter is deactivated and shows the poor conversion efficiency. This paper presents effEcts of engine operating conditions on catalytic converter temperature in a SI engine, which are the indications of catalytic deactivation. Exhaust gas temperature and catalyst temperature were measured as a function of air/fuel ratio, ignition timing and misfire rates. Additionally, light-off time was measured to investigate the effect of operating conditions. It was found that ignition retard and misfire can result in the deactivation of the catalytic converter, which eventually leads the drastic thermal aging of the converter. Significant reduction in light-off time can be achieved with proper control of ignition retard and misfire, which can reduce cold-start HC emissions as well.

• Journal of the Korean Institute of Gas
• /
• v.19 no.6
• /
• pp.80-84
• /
• 2015

In this paper, the valves for a LPG gas cylinder have been investigated on the body height and weight by comparing design data between typical automatic shut-off vertical and newly developed horizontal valves. The height of an automatic shut-off horizontal valve is radically reduced by 41~42% compared with that of a typical automatic shut-off vertical valve. And, the body weight of a horizontal valve is also reduced by 29~40% compared with that of a vertical shut-off valve. This result is just achieved by a structural design modification from typical vertical valve to horizontal arrangement of various valve components.

• YAKHAK HOEJI
• /
• v.58 no.2
• /
• pp.112-124
• /
• 2014

This study aimed to develop a regulation system for off-label drug use to secure the safe use of marketed drugs. We searched governmental documents for national and global regulating systems of off-label drug uses and a body of academic literature to explore current regulating trends. We included European Union, United Kingdom, United States of America, Australia and Japan, and critically reviewed the regulation of off-label drug use in four issues, which were a regulatory structure, safety control before and after off-label use, and information management. The findings of the present investigation called for several measures in off-label drug uses: enhancing prescribers' self-regulation, providing up-to-date information to prescribers for evidence-based practice and to patients for their informed consent, making evidence with scientific rigor, building an official registering process for off-label use in good quality and extending the role of pharmaceutical industry in pharmacovigilance. At last, we proposed a new system so as to regulate and evaluate off-label drug uses both at national and institutional level. In the new system, we suggested a clear-cut definition for clinical evidence that applicants would submit. We newly introduced an official 'Off-Label Drug Use Report' to evaluate the safety and clinical efficacy of a given off-label drug use. In addition, we developed an algorism of the regulation of off-label drug use within an institution to help set up the culture of evidence-based practices in off-label drug uses.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.973-974
• /
• 2013