• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.165-168
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• 2002

As the demand for higher data-rate chip-to-chip communication such as memory-to-controller, processor-to-processor increases, low cost high-speed serial links\ulcorner become more attractive. This paper describes a 0.25-fm CMOS 1.6Gbps/pin 4-level transceiver using Stub Series Terminated Logic for high Bandwidth. For multi-gigabit/second application, the data rate is limited by Inter-Symbol Interference (ISI) caused by channel low pass effects, process-limited on-chip clock frequency, and serial link distance. The proposed transceiver uses multi-level signaling (4-level Pulse Amplitude Modulation) using push-pull type, double data rate and flash sampling. To reduce Process-Voltage-Temperature Variation and ISI including data dependency skew, the proposed high-speed calibration circuits with voltage swing controller, data linearity controller and slew rate controller maintains desirable output waveform and makes less sensitive output. In order to detect successfully the transmitted 1.6Gbps/pin 4-level data, the receiver is designed as simultaneous type with a kick - back noise-isolated reference voltage line structure and a 3-stage Gate-Isolated sense amplifier. The transceiver, which was fabricated using a 0.25 fm CMOS process, performs data rate of 1.6 ~ 2.0 Gbps/pin with a 400MHB internal clock, Stub Series Terminated Logic ever in 2.25 ~ 2.75V supply voltage. and occupied 500 * 6001m of area.

• 토지주택연구
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• 제10권3호
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• pp.67-75
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• 2019

The modular construction means that more than 70% of the parts such as walls, windows, electrical wiring, facility piping, bathrooms, and kitchen appliances are pre-assembled at the factory and transported to the site. It is possible to shorten the construction period than general construction work and to secure high quality through modular mass production since the modular construction works in the field at the same time as the modular production. However, there are only four domestic modular manufacturers, and each company's modular components and construction methods are different, so it is necessary to standardize them. Therefore, this study investigated the construction process centering on the stacking method of modular housing construction work applied to D site in Cheonan-si, and proposed the key points of quality management by construction stage. As the project was conducted as a pilot project for government R&D projects, some differences may occur from general modular housing construction. However, the construction process and quality control focus of each unit box type modular house analyzed in this study can be used as basic data in the future of modular housing construction. In addition, the results of this study can be used to establish construction standards, such as the development of checklists and establishment of standard processes.

• 소성∙가공
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• 제26권2호
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• pp.79-86
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• 2017

In this study, the sheet metal forming process of the brake chamber head, which had a complex shape compared to the conventional head part, was investigated using finite element (FE) analysis. In order to prevent the forming failures such as necking and fracture, the multi-stage forming process was introduced. The forming process consisted of three steps: (1) first drawing, (2) second drawing, (3) final forming. Experimental and FE simulated results of the brake chamber head were compared, and the results showed that the required characteristics of the straightness and the wall thickness at each location were satisfied.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.208-211
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• 2001

In the drawing from round billet to non-circular section there are two different processes through solid hole die(HD) and the other cassette roller dies(CRD). The CRD process has several cassette type rollers and a billet is able to move through the given gaps between two profiled rollers. The objective of this study is based on the analysis and evaluation of two aforementioned processes using experiments and finite element simulation. In order to simulate the multi-stage drawing process from circular sectioned billet to rounded square section, the finite element analysis is applied to the process using a commercially available DEFORM-3D code. Two types of experimental drawing tests through designed and manufactured dies for pure copper and aluminum alloy are carried out at room temperature. The analysis included comparison of material properties before and after drawing of each process and also provide some useful information by a FEM simulation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.628-631
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• 2002

This paper has executed FE-analysis to review the feasibility for developing the process, which produces the narrow-cubic type cans, using the Backward Impact Extrusion process instead of using current process, multi-stage deep drawing. Proposes an analysis method by applying ALE(Arbitrary Lagrangian-Eulerian) description to non-axisymmetric extrusion. which is appreciated as one of good solution to mesh distortion in case of the large deformation plasticity process that has mass flux, and considers the factors which affects forming-loads related to punch velocity and fulid status of material.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.190-195
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• 2001

The piercing and blanking of thin sheet metal working is specified division in press die design and making. In order to prevent the defects, the optimum design of the production part, strip process layout, die design, die making and try out etc. are necessary the analysis of effective factors. For example, theory and practice of metal shearing process and it's phenomena, die structure, machine tool working for die making, die materials and it's heat treatment, metal working in field, their know how etc. are included in those factors. In this study, we analyzed whole of data base, theoretical back ground of metal working process, and then performed the progressive die tryout with the screw press.

• 환경위생공학
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• 제12권3호
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• pp.95-102
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• 1997

The process which can stabilize water quality of treatment and improve nitrogen removal rate under the condition of high organic loading was developed by charging fibrous HBC media to single sludge nitrification-denitrification process. This process was operated easier, minimized the treatment cost, and shortened the retention time. To improve T-N removal rate, a part of nitrifing liquid at aerobic zone was recycled to anoxic zone by approximate internal recycle ratio. The experimental results are as follows ; T-N removal efficiency in the organic volumetric loading 0.14-0.19 kg/COD/m$^{3}$·d was obtained asmaxium of 85% at internal recycle ratio 2.5 and in more ratio than this it was decreased. Organic removal efficiency was about 91% under the overall experimental conditions and not influenced by recycle ratio.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 추계학술대회 논문집
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• pp.141-148
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• 1994

In order to improve the productivity of cold forging at low production cost, an integrated system's approach is necessary in handling the material preparation and the optimum process design, considering the forming machines, tooling, and operation including quality control. As the first step toward this approach, an expert system for multi-stage cold forging process design for fasteners with various head geometries is developed using Prolog language on IBM 486 PC. For effective representation of the complex part geometries, the system uses the multiple element input, and the forward inference scheme in determination of the initial billet size and intermediate forging steps. In order to determine intermediate steps, the basic empirical rules for extrusion, heading, and trimming were applied. The required forming loads and global strain distributions at each forging step were calculated and displayed on the PC monitor. The designed process sequence drawing can be obtained by AutoCAD. The developed system will be useful in reducing trial and error of design engineers in determining the diameter and height of the initial cylindrical billet from the final product geometry and the intermediate necessary sequences.

• International Journal of Control, Automation, and Systems
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• 제2권3호
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• pp.263-278
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• 2004

This paper reviews dynamic programming (DP), surveys approximate solution methods for it, and considers their applicability to process control problems. Reinforcement Learning (RL) and Neuro-Dynamic Programming (NDP), which can be viewed as approximate DP techniques, are already established techniques for solving difficult multi-stage decision problems in the fields of operations research, computer science, and robotics. Owing to the significant disparity of problem formulations and objective, however, the algorithms and techniques available from these fields are not directly applicable to process control problems, and reformulations based on accurate understanding of these techniques are needed. We categorize the currently available approximate solution techniques fur dynamic programming and identify those most suitable for process control problems. Several open issues are also identified and discussed.

• 전력전자학회논문지
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• 제14권5호
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• pp.343-354
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• 2009

본 논문에서는 집적 가능한 전력변환기 제작을 위하여 자화 소자가 없는 전력용 직류-직류 변환기를 제안하였다. 자화 소자가 없는 대신, 압전 트랜스듀서의 유도성 임피던스 구간을 사용함으로써 에너지 저장 및 소프트 스위칭을 위한 공진파형을 구현하였다. 압전소자는 권선이 없고 전극을 사용하여 전력을 전달하므로, 반도체 공정을 통한 대량생산이 가능한 장점이 있다. 본 논문에서는 압전 트랜스듀서를 적용가능한 승압형 공진형 직류-직류 변환 회로를 제안하고, 동작모드 및 주파수 제어 특성을 분석하였다. 또한, 단일 컨버터를 확장한 다중 직렬형 토폴로지를 살펴보고, 동일하게 주파수 제어 특성을 분석하였다. 분석 결과를 검증하기 위하여 10W 출력 직류-직류 전력변환기 하드웨어를 제작하였다. 또한 확장형 다중 직렬 컨버터 하드웨어를 제작하여 검증하였다. 단일 컨버터와 동일하게 주파수 제어 특성을 보였으며, 전력변환기로 매우 우수한 효율 성능을 보임을 알 수 있었다.