• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.55-64
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• 2006

This work proposes a calibration-free 14b 70MS/s 0.13um CMOS ADC for high-performance integrated systems such as WLAN and high-definition video systems simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs signal insensitive 3-D fully symmetric layout techniques in two MDACs for high matching accuracy without any calibration. A three-stage pipeline architecture minimizes power consumption and chip area at the target resolution and sampling rate. The input SHA with a controlled trans-conductance ratio of two amplifier stages simultaneously achieves high gain and high phase margin with gate-bootstrapped sampling switches for 14b input accuracy at the Nyquist frequency. A back-end sub-ranging flash ADC with open-loop offset cancellation and interpolation achieves 6b accuracy at 70MS/s. Low-noise current and voltage references are employed on chip with optional off-chip reference voltages. The prototype ADC implemented in a 0.13um CMOS is based on a 0.35um minimum channel length for 2.5V applications. The measured DNL and INL are within 0.65LSB and l.80LSB, respectively. The prototype ADC shows maximum SNDR and SFDR of 66dB and 81dB and a power consumption of 235mW at 70MS/s. The active die area is $3.3mm^2$.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.51-57
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• 2015

In this paper, in order to design the A / D converter with a high resolution of 14 bits or more for the biological signal processing, CMOS delta sigma modulator that is a 1.8V power supply voltage - were designed. we propose a new structure of The fourth order delta-sigma modulator that needs four op amps but we use only two op amps. By using a time -interleaving technique, we can re-construct the circuit and reuse the op amps. Also, we proposed a KT/C noise reduction circuit to reduce the thermal noise from a noisy resistor. We adjust the size of sampling capacitor between sampling time and integrating time, so we can reduce almost a half of KT/C noise. The measurement results of the chip is fabricated using a Magna 0.18um CMOS n-well1 poly 6 metal process. Power consumption is $828{\mu}W$ from a 1.8V supply voltage. The peak SNDR is measured as a 75.7dB and 81.3dB of DR at 1kHz input frequency and 256kHz sampling frequency. Measurement results show that KT/C noise reduction circuit enhance the 3dB of SNDR. FOM of the circuit is calculated to be 142dB and 41pJ / step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.61-67
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• 2017

Research into the selection of suitable materials and the development of fast processing methods for press die manufacturing is absolutely necessary to reduce the production time and cost. In particular, knowledge of its heat properties must be considered whendeveloping a long press die. Generally, as the main component materials of press dies, Cr, W low alloy tool steel, high carbon-high chrome steel, high speed steel, etc., are used as thetooling steel for the cold die. Machine tools and wire-cut electric discharge machining are mainly used for processing the press die parts. There are many differences in the machining time and life cycle of die parts depending on the machining process. The parts produced by milling and grinding have a high manufacturing time and cost with a long life cycle, while thosemade by milling and wire-cut discharge machining have areduced manufacturing time and cost,whereastheir die life cycle is reduced. Therefore, in this study, we will discuss amethod of improving the life cycle of the die parts by using heat treatment as a processing method that reduces the manufacturing time and cost. SEM, EDS analysis and the surface roughness analysis of the surface and center of the workpiece are used for analyzing the specimens produced by three machining methods, viz. milling - grinding, milling - wire cut discharge, and milling - wire cut discharge - heat treatment. A method of making die parts having the same life cycle as those produced by milling - grinding is developed with the milling - wire cut discharge - high temperature tempering method.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.84-91
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• 2017

Recent years have witnessed the increased usage of flammable metals, such as aluminum or magnesium, in wide range of high-tech industries. These metals are indispensable for the improvement of physical properties of materials as well as the design capability of the final product. During the process, unwanted metal dusts could be released to the environment. This can lead to an occupational health and safety issues. Due to their flammable nature, more serious problem of an explosion can happen in extreme cases. The explosion is the combustion of tiny solid particles and vapor mixture, caused by pyrolysis. This complex composition makes engineering analysis more difficult, compared to simple gas explosions or vapor cloud combustions. The study was conducted to assess this light metal dust explosion in an effort to provide the bases for a risk assessment. Dust explosion characteristics of each material was carefully evaluated and an appropriate analysis tool was developed. A comprehensive database was also constructed and utilized for the calibration of the developed response model and the verification for its accuracy. Subsequently, guidelines were provided to prevent dust explosions that could occur in top-notch industrial processes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.11
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• pp.755-759
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• 2016

The use of heat pipes in the electronic telecommunication field is increasing. Among the various types of heat pipes, the thin flat heat pipe has relatively high applicability compared with the circular heat pipe in the electronic packaging application. The thin flat heat pipe based on extrusion fabrication has a simple capillary wick structure consisting of rectangular cross sectional grooves on the inner wall of the pipe. Although the groove serves as a simple capillary wick, and many such grooves are provided on the inner wall, it is difficult for the grooves to realize a sufficiently high capillary force. In the present study, a thin flat heat pipe with a wire bundle was developed to overcome the drawback of poor capillary force in the thin flat heat pipe with grooves, and was evaluated by conducting tests. In the performance test, the thin flat heat pipe with the wire bundle showed a lower thermal resistance of approximately 3.4 times, and a higher heat transfer rate of approximately 3.8 times with respect to the thin flat heat pipe with grooves as the capillary wick respectively. The possibility of using the wire bundle as a capillary wick in the heat pipe was validated in the present study; further study for commercializing this concept will be taken up in the future.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.170.1-170.1
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• 2015

안티모니 (Sb)를 기반으로 한 제2형 초격자 (Type II superlattice, T2SL)구조 적외선 검출기 연구는 2000년대 들어 Sb 계열의 화합물 반도체 성장 기술이 발전함에 따라 HgCdTe (MCT), InSb, 양자우물 적외선 검출기 (QWIP)를 대체할 수 있는 고성능의 양자형 적외선 검출 소재로 부상하였으며, 현재 전 세계적으로 활발한 연구가 진행되고 있다. 특히, 기존의 양자형 적외선 검출소자에 비해 전자의 유효질량이 상대적으로 커서 밴드 간의 투과전류가 줄어들 뿐만 아니라, 전자와 정공이 서로 다른 물질 영역에 분포하여 Auger 재결합률을 효과적으로 줄일 수 있어 상온 동작이 가능한 소재로 주목을 받고 있다. 또한, T2SL 구조는 초격자를 구성하는 물질의 두께나 조성 변화를 통한 밴드갭 변조가 용이하여 단파장에서 장파장 적외선에 이르는 광범위한 파장 대역에서 동작이 가능할 뿐만 아니라 구조적 변화를 통해 이중 대역을 동시에 검출 할 수 있는 차세대 적외선 열영상 소자로 알려져 있다. 본 연구에서는 분자선 에피택시(MBE)법을 이용하여 300 주기의 InAs/GaSb (10/10 ML) 제2형 초격자 구조를 성장하여 적외선 검출소자를 제작하였다. 제2형 초격자 구조를 구성하는 물질계에 p-type dopant인 Be을 이용하여 각각 도핑 농도가 다른 시료를 성장하였다. 이때 p-type 도핑 농도는 각각 $1/5/10{\times}10^{15}cm^{-3}$로 변화를 주었다. 성장된 시료의 구조적 특성 분석을 위해 고분해능 X선 회절 (High resolution X-ray diffraction, HRXRD)법을 이용하였으며, 초격자 한 주기의 두께가 6.2~6.4 nm 로 설계된 구조와 동일하게 성장됨을 확인 하였으며, 1차 위성피크의 반치폭은 30~80 arcsec로 우수한 결정성을 가짐을 확인하였다. 적외선 검출을 위한 $410{\times}410{\mu}m^2$ 크기의 단위 소자 공정을 진행하였으며 이때 적외선의 전면 입사를 위해 소자 위에 $300{\mu}m$의 윈도우 창을 제작하였다. 단위 소자의 측벽에는 표면 누설 전류가 흐르는데 이를 방지하기 위해서 표면보호막을 증착하였다. 적외선 검출 소자의 전기적 특성 평가를 위해 각각의 시료의 암전류 (dark current)와 파장별 반응 (spectral response)을 온도별로 측정하여 비교 및 분석하였다.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.115-120
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• 2000

All solid-state thin film micro-batteries consisting of lithium metal anode, an amorphous LiPON electrolyte and cathode of vanadium oxide have been fabricated and characterized, which were fabricated with cell structure of $Li/LiPON/V_2O_5Pt$. The effect of various oxygen partial pressure on the electrochemical properties of vanadium oxide thin films formed by d.c. reactive sputtering deposition were investigated. The vanadium oxide thin film with deposition condition of $20\%\;O_2/Ar$ ratio showed good cycling behavior. In in-siか process, the LiPON electrolyte was deposited on the $V_2O_5$ films without breaking vacuum by r.f. magnetron sputtering at room temperature. After deposition of the amorphous LiPON, the Li metal films were grown by a thermal evaporator in a dry room. The charge-discharge cycle measurements as a function of current density and voltage variation revealed that the $Li/LiPON/V_2O_5$ thin film had excellent rechargeable properly when current density was $7{\mu}A/cm^2$. and cut-off voltage was between 3.6 and 2.7V In practical experiment, a stopwatch ran on this $Li/LiPON/V_2O_5$ thin film micro-battery. This result means that thin film micro-battery fabricated by in-siか process is a promising for power source for electronic devices.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.93-100
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• 2005

Comparative thickening and dewatering characteristics of municipal wastewater sludge were investigated in terms of separated and combined treatment of primary and secondary BNR sludge. Also, various conditioning methods such as cation polymer addition, steam and ultrasonication treatment were examined to improve dewaterability of sludge. The dewaterability was measured by using specific resistant test, wedge zone simulator and centrifuge. The result of the sludge thickening test revealed that separated thickening was better in terms of solids recovery and supernatant quality. Particularly, the thickening of primary sludge with high solids (about 3.5% TS) showed very poor solid separation. The addition of cation polymer showed better conditioning characteristic for dewatering and the optimal polymer dosage was 0.26% for primary sludge, 0.43% for secondary sludge and 0.38% for combined sludge. Contrary to the result of the thickening, the dewatering test revealed that dewatering of the combined sludge is better than that of separated sludge, representing better solids separation and filtrate quality. The polymer addition was essential to improve dewaterability in filter (belt) press type dewatering but it was inefficient for the dewatering of secondary sludge only. The centrifuge type dewatering showed better performance and the dewaterability was slightly improved when the polymer was added. Based on the results of this research a sustainable sludge treatment process, particularly in terms of the recycle water quality and solids recovery, was proposed.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.375-375
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• 2001

금년 7월 1일부터 개정 시행되는 품질경영촉진 및 공산품안전관리범파, 2002 년 7 월 1 일부터 시행되는 제조물책임(Product Liability； PL)법으로 인하여 제품의 안전성을 제고하기 위한 노력이 정부와 기업. 학계에서 다각도로 진행중이다. 그러나, 그 추진방향들이 아직 제각각이어서 하나의 조직적인 체계를 갖추진 못하고 있다. 그 이유는 제조물책임에 대응하기 위한 제품안전성 향상이 어느 한 분야의 활동으로는 충족시킬 수 없기 때문이지만, 기본적으로는 제품안전이 담당하여야 하는 책임의 범위가 어디까지인지 기업을 비롯한 관계자들이 명확히 이해하고 있지 못하기 때문이다. 본 연구에서는 이와 관련하여, 기존에 이미 시행착오를 겪은 선진국들의 소송사례를 중심으로 제품결함 중 어느 부분에 문제가 제기되는가를 살펴보고, 그 대응책을 제시하고자 하였다. 먼저 제조물책임법의 제정 취지와 법에서 정하고 있는 책임범위가 어디까지인지를 살펴보고, 선진국의 소송사례를 중심으로 그 적용범위를 확인하였다 또한 제조물책임에 대응하기 위한 방법이 어떻게 진행되는지를 살펴보고, 그 중 제품 안전성 (Product Safety) 을 향상시키기 위하여 신뢰성이나 품질측면에서 경영상의 어떤 노력이 경주되어야 하는가를 검토하였다. 한편, 리스크 관리상의 리스크 분석과 위험성 분석과의 관계, 위험성 분석의 기법들, 위험성 분석기법의 선정요령, 제품의 안전성을 평가하기 위하여 기존의 위험성 분석기법을 어떻게 활용할 것인가, 적용상의 문제점은 없는가 검토하였다. 마지막으로, 현재 기업들이 가장 소홀하게 대응하고 있는 표시상의 결함에 대하여 소송 및 보상사례를 살펴보고, 그에 대한 대책으로서 픽토그램, 라벨, 경고문구, 그리고 사용설명서의 작성 및 표시 방안에 대하여 대응방안을 고찰하였다. 용융이 발생될 수 있다. 따라서, 이러한 현상을 방지하기 위해서는 진공 분위기 하에서 적절한 접합 틈새를 유지할 수 있는 공정 및 장비의 개발이 필요하다.(Icing화) 문제가 발생하기 때문에 배기가스의 Icing을 방지하기 위하여 압축기 끝단에서 공기를 추출하여 배기부분에 송출할 필요성이 있는 것으로 판단되었다. 출구가스의 기체 유동속도가 매우 빠르므로 (100-l10m.sec) 이를 완화하기 위한 디퓨저의 설계가 요구된다고 판단된다. 또 연소기 후방에 물을 주입하는 경우 열교환기 및 기타 부분품에 발생할 수 있는 부식 및 열교환 효율 저하도 간과할 수 없는 문제로 파악되었다. 이러한 기술적 문제가 적절히 해결되는 경우 비활성 가스 제너레이터는 민수용으로는 대형 빌딩, 산림, 유조선 등의 화재에 매우 적절히 사용되어 질 수 있을 뿐 아니라 군사적으로도 군사작전 중 및 공군 기지의 화재 그리고 지하벙커에 설치되어 있는 고급 첨단 군사 장비 등의 화재 뿐 아니라 대간첩작전 등에 효과적으로 활용될 수 있을 것으로 판단된다.가 작으며, 본 연소관에 충전된 RDX/AP계 추진제의 경우 추진제의 습기투과에 의한 추진제 물성 변화는 미미한 것으로 나타났다.의 향상으로, 음성개선에 효과적이라고 사료되었으며, 이 방법이 편측 성대마비 환자의 효과적인 음성개선의 치료방법의 하나로 응용될 수 있으리라 생각된다..7%), 혈액투석, 식도부분절제술 및 위루술·위회장문합술을 시행한 경우가 각 1례(2.9%)씩이었다. 13) 심각한 합병증은 9례(26.5%)에서 보였는데 그중 식도협착증이 6례(17.6%), 급성신부전증 1례(2.9%), 종격동기흉과 폐염이 병발한 경우와 폐염이 각 1례(2.9%)였다. 14) 식도경 시행회수는 1회가 17례(54.8%), 2회가 9례(29.0%), 3회 이상이

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.91-96
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• 2005

The silicon-on-insulator (SOI) wafer fabrication technique has been developed by using ion-cut process, based on proton implantation and wafer bonding techniques. It has been shown by SRIM simulation that 65keV proton implantation is required for a SOI wafer (200nm SOI, 400nm BOX) fabrication. In order to investigate the optimum proton dose and primary annealing condition for wafer splitting, the surface morphologic change has been observed such as blistering and flaking. As a result, effective dose is found to be in the $6\~9\times10^{16}\;H^+/cm^2$ range, and the annealing at $550^{\circ}C$ for 30 minutes is expected to be optimum for wafer splitting. Direct wafer bonding is performed by joining two wafers together after creating hydrophilic surfaces by a modified RCA cleaning, and IR inspection is followed to ensure a void free bonding. The wafer splitting was accomplished by annealing at the predetermined optimum condition, and high temperature annealing was then performed at $1,100^{\circ}C$ for 60 minutes to stabilize the bonding interface. TEM observation revealed no detectable defect at the SOI structure, and the interface trap charge density at the upper interface of the BOX was measured to be low enough to keep 'thermal' quality.