• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.2
• /
• pp.268-274
• /
• 2013

Electric discharge machining drill (EDM-drill) is an efficient process for the fabrication of micro-diameter deep metal hole. As there is non-physical contact between tool (electrode) and workpiece, EDM-drill is widely used to machine the hard machining materials such as high strength steel, cemented carbide, titanium alloys. The electro-thermal energy forces the electrode to wear out together with the workpiece to be machined. The electrode wear occurs inside of a machining hole. and It causes hard to monitor the machining state, which leads the productivity and the quality to decrease. Thus, this study presents a methodology to estimated the electrode wear amount while two coefficients (scale factor and shape factor) of the logarithmic regression model are evaluated from the experiment result. To increase the accuracy of estimation model, the linear transformation method is adopted using the differences of initial electrode wear differences. The estimation model is verified through experiment. The experimental result shows that within minute error, the estimation model is able to predict accurately.

• Journal of Korean Society of Steel Construction
• /
• v.25 no.5
• /
• pp.531-541
• /
• 2013

This paper investigated the structural capacity of the CT shear connectors, which is a kind of the perfobond rib and functions as an anchor transferring the tension force in the joint between a composite PHC wall pile and a bottom slab. The direct pull-out test was performed for various specimens. From failure modes and load-displacement curves, it was found that transverse rebars should be placed to holes in a web to restrict pull-out failure of CT shear connectors. The results of additional tests for specimens with transverse rebars and various support lengths indicated that all specimens were failed by the tension failure of PHC pile before pull-out failure of CT shear connector and concrete pull-out failure. Thus, the CT shear connector could endure the tension force between the PHC wall pile and the bottom slab.

• Korean Journal of Social Welfare
• /
• v.66 no.3
• /
• pp.29-53
• /
• 2014

This research is to study the economical, psychsocial, physical pains of the elderly mens living alone and the process being out of the isolated life. From this, we expect to propose a supportive program to help the living alone of the elderly mens. Six of the elderly mens living alone joined this research and the hermeneutical grounded theory methodology was applied to interpret it. Data were collected by the depth interview and various written records and they were analyzed by Rennie(2007)'s methodology. We could construct 13 categories by analyzing and categorizing meaningful units of the data. The core theme of the living alone experience was presented as "Accepting self-existence forgotten in the swamp of isolation and preparing for the blessed death." Based upon the research outcomes, we suggested a social supportive program considering the elderly men's characters and a way to improve the accessibility to the therapy system for the elderly mens living alone and the need for a meaning therapy.

• Electronics and Telecommunications Trends
• /
• v.27 no.1
• /
• pp.51-60
• /
• 2012

실리콘 관통 홀(TSV) 기술은 2006년 삼성전자가 낸드 플래시 메모리에 적용하여 적층된 시제품을 선보인 이후 선풍적인 기술적 관심을 불러일으키고 있다. 그러나, 안타깝게도 CMOS 이미지 센서 모듈 외에는 실제로 양산에 적용되고 있는 사례가 매우 드물다. 이는 기술적으로, 그리고 상업적으로도 극복해야 하는 어려움이 많기 때문이다. 최근 Xilinx사는 28nm FPGA를 네 개의 작은 칩으로 분리하여 TSV가 있는 실리콘 인터포저 위에 2차원적으로 집적한 제품을 고객사들에게 선적하기 시작했다. 이와 같은 2.5D 집적 기술은 3D IC 집적 기술의 상용화를 위한 중간 단계로 여겨질 뿐만 아니라 그 자체로 독립적인 시장을 형성할 기술로도 판단되고 있다. 본고에서는 2.5D 집적을 위한 인터포저 기술개발 및 표준화 동향에 대해 소개하고자 한다.

• Proceedings of the KIPE Conference
• /
• 2019.11a
• /
• pp.90-92
• /
• 2019

본 논문은 GaN 디바이스를 사용하는 전력변환장치에서 Pick-up coil을 PCB 패턴으로 구현하여 전류를 측정하는 기법에 관하여 제안한다. 기존에 사용되는 PCB 패턴 코일 구조의 경우 PCB 이중층만 구성하여 관통 홀이나 추가공정이 필요함에 비해 본 논문에서 제안한 PCB 패턴 코일 구조의 경우 다층기판을 사용하여 코일을 구성함으로서 기존의 패턴에 비해 높은 상호 인덕턴스 값을 가지게 되고, 코일의 출력 전압값이 높아져 더 높은 감도를 가지게 된다. 또한 PCB 외부의 추가적인 공정 작업이 없이 구성이 되었다. 전류 측정은 코일 뒷단에 적분기를 통합하여 구성하였으며, 시뮬레이션을 통해 전류 측정 성능을 검증한다.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.4
• /
• pp.356-363
• /
• 2003

An eddy current testing system was developed for detection of flaws in the ferromagnetic steel tubes. Because the eddy current signals from the ferromagnetic steel tubes could be distorted easily due to an irregularity of magnetic permeability, magnetic saturation is required to suppress this variation of magnetic fields. A magnetic saturation probe with the Hemholtz coil was designed for the inspection of the steel tubes. The bandwidth pass filters were adapted to minimize the noise from the DC magnetization. When using the designed test probe, the flaw signals could be discriminated from the noise. The system was tested at the production line and showed a capability of detecting flaws, like a drilled hole of the diameter of 2.0mm at the moving speed of 1m/sec.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.4
• /
• pp.1-7
• /
• 2013

DME spray characteristics were investigated about varied ambient pressure and fuel injection pressure using the DME common rail fuel injection system when the nozzle holes diameter is varied. The common rail fuel injection system with DME cooling system was used since DME has properties of compressibility and vaporization in atmospheric temperature. The fuel injection quantity and spray characteristics were measured. The spray analysis parameters were spray shape, penetration length, and spray angle at six nozzle holes. Three types of injector were used, the nozzle holes diameter were 0.166 mm (Injector 1), 0.250 mm (Injector 2), and 0.250 mm with enlargement of orifice hole from 0.6 mm to 1.0 mm (Injector 3). The fuel injection pressure was varied by 5MPa from 35 to 70MPa when the ambient pressure was varied 0, 2.5, and 5MPa. When using Injector 3 in comparison to the others, the DME injection quantity was increased 1.69 ~ 2.02 times. Through this, it had the similar low heat value with diesel which was injected Injector 1. Among three types of injector, Injector 3 had the fastest development velocity of penetration length. In case of spray angle, Injector 2 had the largest spray angle. Through these results, only the way enlargement the nozzle holes diameter is not the solution of DME low heat value problem.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.3
• /
• pp.73-79
• /
• 2008

Atomization speed of diesel fuel injected from 8-hole nozzle is faster than that of 7-hole nozzle because the hole diameter of 8-hole nozzle is smaller than that of 7-hole nozzle. But both insufficient distance between the fuel sprays and short penetration of injected sprays through 8-hole nozzle hole cause many harmful effects on combustion. In this study, we installed the 8-hole injectors to diesel 2.0 liter class engine, and optimized in-cylinder swirl and penetration via selecting and matching proper cylinder head and combustion bowl. Through this process, we found out the performance and emission potential of 8-hole nozzle installed engine are better than those of 7-hole nozzle installed one.

• The Journal of Korean Philosophical History
• /
• no.30
• /
• pp.227-257
• /
• 2010

This paper intends to articulate concretely the contents and methods of Confucius self-cultivation and their practical characteristics through the analysis of S?nsan Wang Fuzhi (船山 王夫之, 1619~1692)'s On Reading Four Classics - Chungyong 讀四書大全說-中庸. The essence of the practical philosophy that penetrates Chungyong (中庸: The Doctrine of the Mean) is the practice of self-cultivation through Chonyang (存養: Preserving one's self) and $S{\breve{o}}ngchal$ (省察: Self-reflection). It can come down to two cultivation practices: 1) careful and discrete thinking without seeing or listening (Kyesingonggu: 戒愼恐懼), 2) solely looking into what is hidden and covert (Sindok: 愼獨). $S{\breve{o}}nsan$ grasped the importance of the two concepts for practical philosophy and articulated the principles of practical self-cultivation of Chungyong by paying attention to the differences and mutual-relations of the two concepts. Especially, he put the emphasis on the study through Chonyang and then focused on the relations between Chonyang and $S{\breve{o}}ngchal$. He consistently argued that the Kyesingonggu's Chonyang study was what enabled the Sindok's $S{\breve{o}}ngchal$ study and clarified the meanings of Chonyang in self-cultivation. Furthermore, he established the self-cultivation study of Chungyong as the primary self-cultivation theory of Confucianism by maximizing the practical characteristics within $Chonyangs{\breve{o}}ngchal$.

• Journal of Korean Institute of Industrial Engineers
• /
• v.38 no.3
• /
• pp.220-226
• /
• 2012

The Electric discharge machining (EDM) process is used to minimize the difference between designed feature and machined feature while the most workpiece is removed through the cutting processes. The tiny-deep hole machining and perpendicular wall machining in mold and die are good applications of EDM. Among EDM equipment, the super drill uses the hollowed electrode to eliminate the debris which causes the second discharge with the electrode and degrades the machining quality. Through the hollow, the high pressured discharge oil is supplied to remove the debris together with the spindle rotation. The thin-hollow electrode tends to easily wear out compared to the sold die-sinking electrode and its wear rate is might not allowed to monitor in real time during discharging. Up to now, the wear amount is measured by off line method, which leads machining time to increase because the hole pass-through moment can be check by visual (manually) with the extra tool path. Therefore, this study suggests the attractive method to evaluate the hole pass-through moment in which the gap voltage and z-axis encoder pulse are monitored to predict the moment. The commercial super drill is used to validate the proposed method and the experiment is carried out.