• Journal of Welding and Joining
• /
• v.28 no.4
• /
• pp.55-60
• /
• 2010

The purpose of this paper is to propose a mathematical model of welding current for the P-GMAW by modifying the well known GMAW model. Welding power circuit is simply modeled as a RL electric circuit and solved as an ODE equation. The welding current depends on the joint shape, molten pool and welding parameters. To compare the molten pool effect to the welding current, CFD numerical simulation technique was adopted. Welding experiment is also conducted with the same welding parameters as used in numerical simulations to verify the proposed welding current model. The current model which is considered molten pool shape, is more fit to experiment result.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.1
• /
• pp.78-85
• /
• 2013

This paper presents the sliding mode control methods for anti-lock brake system (ABS) with the friction force observer. Using a simplified quarter car model, the sliding mode controller for ABS is designed to track the desired wheel slip ratio. Here, new method to find the desired wheel slip ratio which produces the maximum friction force between road and tire is suggested. The desired wheel slip ratio is varying according road and tire conditions to produce maximum friction force. In order to find optimum desired wheel slip ratio, the sliding mode observer for friction force is used. The proposed sliding mode controller with observer is evaluated in simulation, and the control design is shown to have high performance on roads with constant and varying adhesion coefficients.

• Journal of the Korean Society of Industry Convergence
• /
• v.12 no.1
• /
• pp.43-50
• /
• 2009

The manufacturing process of the semiconductor is guided by the controller, which is supposed to sense the unexpected shocks and/or vibrations to shutdown the hard disk and the whole system in order to prevent the malfunction. This feature of controller would shutdown the system due to the instability of the controller itself as well as the instability of the manufacturing system. And consequently will cause significant losses. In this study the structure of a controller has been investigated to find ways to suppress the vibrations from the structure. The frequency response test and the computer simulation has been implemented to find the structure with improved stability. The result of the study shows that the relatively simple design alterations can eliminate most of the vibrations.

• KIEE International Transactions on Power Engineering
• /
• v.4A no.3
• /
• pp.115-121
• /
• 2004

This paper presents the model for an AC electric railway system using the PSCAD/EMTDC program. It is composed of a scott-transformer, an auto-transformer, catenary and electric trains, etc. After obtaining the models of the fundamental elements describing the AC electric railway system and its behavior, we have analyzed and tested an actual AC electric railway system focused on the amplification of harmonic current to verify the proposed model. The simulation results from the proposed approach and the measurement data from the test are described.

• Journal of Computational Design and Engineering
• /
• v.2 no.3
• /
• pp.165-175
• /
• 2015

One of the current challenges in the domain of the multicriteria shape optimization is to reduce the calculation time required by conventional methods. The high computational cost is due to the high number of simulation or function calls required by these methods. Recently, several studies have been led to overcome this problem by integrating a metamodel in the overall optimization loop. In this paper, we perform a coupling between the Normal Boundary Intersection - NBI - algorithm with Radial Basis Function - RBF - metamodel in order to have a simple tool with a reasonable calculation time to solve multicriteria optimization problems. First, we apply our approach to academic test cases. Then, we validate our method against an industrial case, namely, shape optimization of the bottom of an aerosol can undergoing nonlinear elasto-plastic deformation. Then, in order to select solutions among the Pareto efficient ones, we use the same surrogate approach to implement a method to compute Nash and Kalai-Smorodinsky equilibria.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2017.11a
• /
• pp.211-213
• /
• 2017

최근 보안적 이슈에 따른 피해가 지속적으로 늘어남에 따라 사람들이 보안에 관심이 많아 지기 시작했다. 모의해킹 분야의 경우 기존에 문제 풀이 웹 사이트들이 존재하지만 회원 가입 단계로부터 입문자들이 시작하기에는 높은 진입장벽이 존재한다. 본 연구에서는 방 탈출 게임의 컨셉을 모의해킹에 적용하여 모의해킹 문제를 게임을 푸는 방식으로 접근하여 입문자들도 쉽게 모의해킹 분야를 시작할 수 있도록 하였다. 웹 서버는 오픈소스 웹 방화벽인 ModSecurity와 Spring Security로 서버보안을 강화하였다.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.465-466
• /
• 2006

In this paper, novel analog duty cycle corrector (DCC) with a digital duty error detector is proposed. The digital duty error detector measures the duty error of the clock and converts it into a digital code. This digital code is then used to accurately correct the duty ratio by adaptively steering the charge-pump current. The proposed duty cycle corrector was implemented using an 80nm DRAM process with 1.8V supply voltage. The simulation result shows that the proposed duty cycle corrector improves the settling time up to $70{\sim}80%$ at 500MHz clock frequency for the same duty correction accuracy as the conventional analog DCC.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2015.10a
• /
• pp.155-156
• /
• 2015

최근 선박의 연료유 절감 및 경제운항에 대한 관심이 높아지면서 조선소를 중심으로 운항정보의 활용과 관련된 다수의 프로젝트가 진행되고 있으며 선박 설계, 기상예보 등을 통합한 다양한 시스템이 개발되는 등 선박의 최적운항지원 솔루션 시장이 빠르게 성장하고 있다. 하지만 현재 시장을 주도하고 있는 솔루션들은 설계정보를 중심으로 개발되어 선박을 운영하는 해운선사에서 요구하고 있는 성능기준을 만족하지 못하는 단점이 있다. 따라서 본 연구에서는 운영단계에서 축적되는 운항데이터와 해운선사의 경험과 노하우에 대한 정보가 반영된 경제운항 알고리즘을 개발하기 위한 현황 분석을 수행하였다.

• IE interfaces
• /
• v.16 no.spc
• /
• pp.1-6
• /
• 2003

This study deals with the problem of selecting 6 sigma projects. Traditionally, such selection was based on CTQ (critical to quality) or COPQ (cost of poor quality) derived within business units. Since the objective of 6 sigma is to achieve business goals in a short period, 6 sigma projects should be selected and carried out in coincidence with the whole company's strategies. This paper proposes two methods of selecting 6 sigma projects: one is to identify CTQ's by analyzing the company's BSC's (balanced score card) and then deploying them into subunits of the company and the other is to identify those projects with large hidden COPQ or cost of waste by applying value stream analysis and process model simulation to derive process cost models.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.5 no.4
• /
• pp.206-210
• /
• 2012

In this paper wireless power transmission is discussed. The concept of non-radiative magnetic coupled resonance type wireless power transmission was introduced by MIT team at 2007, non-radiative type has been focused by many researchers. Authors present design of circuit parameters including driving frequency and verify the design by computer simulation.