• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.35-42
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• 2007

This paper presents an INS(Inertial Navigation System) grade, surface micro-machined differential resonant accelerometer(DRXL) manufactured by an epitaxially grown thick poly silicon process. The proposed DRXL system generates a differential digital output upon an applied acceleration, in which frequency transition is measured due to gap dependent electrical stiffness change. To facilitate the resonance dynamics of the electromechanical system, the micromachined DRXL device is packaged by using the wafer level vacuum sealing process. To test the DRXL performance, a nonlinear self-oscillation loop is designed based on the extended describing function technique. The oscillation loop is implemented using discrete electronic elements including precision charge amplifier and hard feedback nonlinearity. The performance test of the DRXL system shows that the sensitivity of the accelerometer is 24 Hz/g and its long term bias stability is about 2 mg($1{\sigma}$) with dynamic range of ${\sigma}70g$.

• 전자공학회논문지A
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• 제33A권12호
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• pp.65-71
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• 1996

A novel lateral field emitter triode has been designed and fabricated. It has self-vacuum environmets and low turn-on voltage, so that the chief problems of previous field emission devices such as additional vacuum sealing process and high turn-on voltage are settled. An in-situ vaccum encapsulation empolying recessed cavities by isotropic RIE (reactive ion etch) method and an electron beam evaporated molybdenum vacuum seals are implemented to fabricate the new field emitter triode. The device exhibits low turn-on voltage of 7V, stabel current density of 2.mu.A/tip at V$_{AC}$ = 30V, and high transconductance (g$_{m}$) of 1.7$\mu$S at V$_{AC}$ = 22V. The superb device characteristics are probably due to sub-micron dimension device structure and the pencil type lateral cathode tip employing upper and lower LOCOS oxidation.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.1173-1176
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• 2010

회전익 항공기의 연료탱크는 피탄으로 인해 연료 누유시 발생할 수 있는 화염으로부터 기체와 승무원의 생존성을 높이기 위하여 연료누설을 차단하는 자기밀폐 기능이 필수적으로 요구된다. 자기밀폐 기능은 내부에 적층된 자기밀폐 소재가 누설되는 연료와 화학반응을 일으켜 급속히 팽창됨으로써 피탄부를 막아, 연료누설을 차단하는 역할을 한다. 본 연구는 미군사규격(MIL-DTL-27422D) 기준으로 국내에서 제작 및 수행한 회전익 항공기의 연료탱크 자기밀폐 성능시험 평가 결과를 제시한다.

• 항공우주시스템공학회지
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• 제2권2호
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• pp.14-19
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• 2008

This paper presents the procedure and the results of the preliminary design of the fuel tank as a part of developing the helicopter. For the requirements of operational capability, MIL-DTL-27422D and Defence Standard 15-2/Issue 1 are considered to be applied in developing a helicopter fuel tank. The procedure of the fuel tank development is set up including interface plate design, tank design, former design, tank material lay-up, and tank installation assessment. The outer moulded line and fittings of fuel tank have being designed, and several test will be performed to get the qualification.

• 항공우주시스템공학회지
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• 제2권2호
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• pp.8-13
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• 2008

The fuel tank systems of fixed wing and rotary wing aircrafts require the self-sealing and crash-worthiness for their survivability. For these requirements, the flexible composite fuel tank is generally used. In this study, the drop and penetration performance of a fuel tank is investigated. The FE simulation includes the drop and penetration test of a fuel tank using MSC.DYTRAN. MSC.DYTRAN can provide the fluid-structure modeling of these test from Euler and Lagrange grids. Using MSC.DYTRAN, the finite modeling of the test cube of the flexible fuel tank and its FE simulation are performed for various environments. The simulation results can show if the test cube satisfies the performance requirements of the fuel tank.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.228-229
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• 2015

In this research, properties of new crack repair materials using organic and inorganic composites (OAI) were investigated under various crack conditions. Especially, this study aims to develop new composites repair materials as needed to follow the crack and its repair method. Crack repair methods such as injection method and surface treatment repair method using self-healing capability for the practical industrial application were examined in comparison with normal crack repair method as a epoxy injection. From these results, it was confirmed that the sealing and injection effects through the cracks from field tests could be improved by OAI.

• 한국치위생학회지
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• 제5권2호
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• pp.147-157
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• 2005

The purpose of this study was to assess how mothers' oral health cognition influence on dental caries status of their children. The 194 children and their mothers were selected for this study. The children were 5, 6, 7 years old in the three day care centers in Ulsan, Korea. Date were collected by oral examination on children and self-administrated questionnaire on their mothers. The questionnaire was surveyed mothers' cognition of oral health and their socio-demographic characteristics. The findings of this study were summarized as follows: 1. The higher mother's income, the lower infant's dental caries, there was significant relation. 2. There were no significant relationship between dental caries preventive cogniton, infant's preventive treatment, between-meals intake and infant's dental caries. 3. There was significant relationship between morther's toothbrushing frequency and infant's dental caries.

• 한국항공우주학회지
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• 제36권10호
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• pp.1032-1037
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• 2008

항공기의 기체 생존성에 있어서 연료탱크는 중요한 부분이다. 회전익 항공기의 연료탱크는 자기 밀폐성과 내충돌성의 기능을 필요로 한다. 이에 따라 고기능유연연료탱크를 필요로한다. 이 논문에서는 상용 소프트웨어인 MSC.DYTRAN을 이용하여 연료탱크의 낙하시험을 시뮬레이션 하였다. 연료탱크 낙하 시험 시 시험 큐브의 파손 없이 내충돌성 요구조건을 만족하는지 알아보았다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 Proceedings of The 6th korea-china joint workshop on nuclear waste management
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• pp.236-244
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• 2005

Radioactive wastes arising from a wide range of human activities are in many different physical and chemical forms, contaminated with varying radioactivity. Their common feature is the potential hazard associated with their radioactivity and the need to manage them in such a way as to protect the human environment. The geological disposal is regarded as the most reasonable and effective way to safely disposal high-level radioactive wastes in the world. The conceptual model of geological disposal in China is based on a multi-barrier system that combines an isolating geological environment with an engineered barrier system. The buffer is one of the main engineered barriers for HLW repository. The buffer material is expected to maintain its low water permeability, self-sealing property, radio nuclides adsorption and retardation property, thermal conductivity, chemical buffering property, overpack supporting property, stress buffering property over a long period of time. Benotite is selected as the main content of buffer material that can satisfy above. GMZ deposit is selected as the candidate supplier for Chinese buffer material of High Level Radioactive waste repository. This paper presents geological features of GMZ deposit and basic property of GMZ Na bentonite. GMZ bentonite deposit is a super large scale deposits with high content of Montmorillonite (about $75\%$) and GMZ-l, which is Na-bentonite produced from GMZ deposit is selected as reference material for Chinese buffer material study.

• 한국진공학회지
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• 제9권1호
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• pp.7-15
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• 2000

An ECR-PECVD system with the characteristics of high ionization rat다 ability of plasma processing in a wide pressure range and deposition at low temperature was manufactured and characterized for the deposition of thin films. The system consists of a vacuum chamber, sample stage, vacuum gauge, vacuum pump, gas injection part, vacuum sealing valve, ECR source and a control part. The control of system is carried out by the microprocessor and the ROM program. We have investigated the vacuum characteristics of ECR-PECVD system, and also have diagnosed the characteristics of ECR microwave plasma by using the Langmuir probe. From the data of system and plasma characterization, we could confirmed the stability of pressure in the vacuum chamber according to the variation of gas flow rate and the effect of ion bombardment by the negative DC self bias voltage. The plasma density was increased with the increase of gas flow rate and ECR power. On the other hand, it was decreased with the increase of horizontal radius and distance between ECR source and probe. The calculated plasma densities were in the range of 49.7\times10^{11}\sim3.7\times10^{12}\textrm{cm}^{-3}$. It is also expected that we can estimate the thickness uniformity of film fabricated by the ECR-PECVD system from the distribution of the plasma density.