• Steel and Composite Structures
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• v.9 no.2
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• pp.173-189
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• 2009

This paper presents a study on the behavior and design of bolted stainless steel plates under in-plane tension. Using an experimentally validated finite element (FE) program strength of stainless steel bolted plates under tension is examined with an emphasis on plate bearing mode of failure. A numerical parametric study was carried out which includes examining the behavior of stainless steel plate models with various proportions, bolt locations and in two different material grades. The models were designed to fail particularly in bolt tear-out and material piling-up modes. In the numerical simulation of the models, non-linear stress-strain material behavior of stainless steel was considered by using expressions which represent the full range of strains up to the ultimate tensile strain. Using the results of the parametric study, the effect of variations in bolt positions, such as end and edge distance and bolt pitch distance on bearing resistance of stainless steel bolted plates under in-plane tension has been investigated. Finally, the results obtained are critically examined using design estimations of the currently available international design guidance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.833-840
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• 1987

A new Block Truncation Coding(BTC) technique reducing the bit-plane and using differential pulse code modulation (DPCM) is proposed and compared with the conventional BTC methods. A new technique decides whether the subblock can be approximated to be uniform or not. If the subblock can be approximated to be uniform(merge mode), we transmit only the gray-level informantion. It not (split mode), we transmity both the bit-plane and the gray-level information. DPCM method is proposed to the encoding of gray-level information when the subblock can be approximated to be uniform. Also modified quantization method is presented to the encoding of gray-level information when the subblock is not uniform. This technique shows the results of coding 256 level images at the average data rate of about 0.75 bits/pel.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.27-34
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• 1989

An adaptive model following controller is designed using the theory of variable structure systems. The proposed method based on the modified condition for the sliding mode allows the designer to satisfy the requirements to speed up the reaching phase and for the magnitude of the chattering to be reduced in the sliding mode. Chattering reduction is obtained by the replacement of control input in the neighborhood of the sliding plane. The results of computer simulation show that state trajectories reach switching plane fast and chattering is reduced.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.179-188
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• 2000

The anodic reaction of hydrogen/oxygen gas mixture at platinum or palladium electrode interfacing with a solid polymer electrolyte was investigated using AC impedance method. The impedance spectrum of the electrode reactions of the mixture depends on the gas composition, electrode roughness, the mode of electrochemical operation and the cell potential. For electrolysis mode of operation, the spectrum taken for the reaction on a rough platinum electrode for the gas mixture revealed clearly that the local anodic reduction of oxygen gas takes place concurrently with the anodic oxidation of hydrogen gas.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.90-98
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• 2010

Microgrid is a small-scale power system composed of distributed generators, energy storage system and loads, and can operate in the grid-connected mode and the islanded mode. This paper presents optimal design procedures for remote microgrid. The design program is based on the economic evaluations including the feasibility study module, optimal combination and allocation of DERs, power network design and the reduction of the GHG emmission. This program which is suggested in this paper shows good performance as a tool of remote microgrid design.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.731-733
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• 1996

In this paper, a new time-domain reduction method for unbalanced 3 phase power systems will be represented. The impulse response of the system is used to identify a discrete-time equivalent filter model. The model is formulated directly in the phase domain. Each phase has a self-mode equivalent model and two mutual-mode equivalent models. The equivalent model is determined by the transfer function identification technique based on the Prony analysis. The model is implemented in EMTDC and tested with an unbalanced 3 phase network. The result of test showed that the equivalent model is accurate.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.287-288
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• 2014

본 논문에서는 3레벨 4레그 컨버터에서 커먼 모드 전압(Common-mode Voltage, CMV)을 저감하기 위한 삼각파 비교 전압 변조 기법을 제안하였다. 제안한 PWM 방법은 매우 직관적이고, DSP 제어 시스템에서 쉽게 구현할 수 있다. SVPWM, SPWM의 스위칭 패턴 분석을 통하여 CMV 저감을 위한 4번째 레그(f상)의 극 전압 패턴을 제안하였고, 해당하는 f상 극 전압의 합성을 위하여, f상 양/음의 극 전압 지령 값을 계산하였다. 또한 a, b, c상 전압 왜곡을 막기 위한 옵셋 전압을 유도하였다. 제안한 PWM 방법의 유효성은 모의실험과 실험 결과를 통하여 검증되었다. 제안된 방법에서 CMV의 첨두치 및 스위칭 수는 SVPWM 방법에 비하여 각각 33%, 25%로 대폭 감소하였다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.17-22
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• 2005

The residual birefringence in molded plastic parts can be divided into two kinds of residual birefringence, i.e., the flow induced residual birefringence produced in flowing stages and the thermally induced residual birefringence produced in cooling stage. In this paper, the effect of new injection-press molding process with normal injection mold, i.e. I) injection-compression mode, ii) injection-press mode, on the distribution of birefringence was studied. It was found that the values of the birefringence was reduced at i) low clamping force and ii) longer mold opening length by injection-press molding.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.854-855
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• 2013

As an unique acoustic characteristic of a Korean bell. beat phenomenon is a periodic repetition of strong and weak sounds. Beat sounds good when it is clear and it has a proper period, however, it is not easy to satisfy these two conditions simultaneously. In this study, we propose a beat tuning method to satisfy these two conditions, by using an equivalent bell model. First, we construct an equivalent bell which has the same beat property with the 1st beat of a real bell and we investigate the change of mode pair by finite element analysis, when thickness of the bell is locally decreased at $22.5^{\circ}$ from the striking point. From the analysis result, minimum thickness reduction amount is determined to make a clear and strong beat.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.159-167
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• 2005

This work focuses on the effects of crack free friction on Mode II stress intensity factors, $K_{II}$, for a vertical surface crack in a two-dimensional finite element model of TiN/steel subject to rolling contact. Results indicate that maximum $K_{II}$ values, which occur when the load is adjacent to the crack, may be significantly reduced in the presence of crack face friction. The reduction is more significant for thick coatings than for thin. Crack extension and increased layer thickness result in increased $K_{II}$ values. The effect of crack face friction on compressive $K_I$ values appears negligible. Comparative results are presented for $MoS_2/steel$ and diamond-like carbon(DLC)/Ti systems.