• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.529-539
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• 1994

In laser heat treatment process of steels, the thin layer of substrate is rapidly heated to the austenitizing temperature and subsequently cooled at a very fast rate due to the self-quenching effect. Consequently, it is transformed to martensitic structure which has low magnetic permeability. This observation facilitates the use of a sensor measuring the change of electromagnetic field induced by the hardening layer. In this paper, the eddy-current electromagnetic field is analyzed by a finite element method. The purpose of this analysis is to investigate how the electrical impedance of the sensor's sensing coil varies with the change in permeability. To achieve this, a numerical model is formulated, taking into consideration the hardening depth, distance of the sensor from the hardened surface and the frequency driving the sensor. The results obtained by numerical simulation show that the eddy-current measurement method can feasibly be used to measure the changing hardening depth within the frequency range from 10 kHz to 50 kHz.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1709-1718
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• 2002

It is well recognized that improving capacity of positive grid in battery is one of key factors for controlling the expected long lift-time of Battery Energy Storage System(B.E.S.S). Thus it is really important to characterized material properties of positive grid which are mainly affected by fabrication process. In this study, two kinds of positive grids, which were fabricated by gravity casting and die-casting technique were used. Micro-structural observation and tensile test were conducted to investigate the effect of fabrication process of positive grid. Ultrasonic measurement based on pulse-echo method and ultrasonic C-scan technique also performed to correlate ultrasonic velocity with porosity ratio in positive grid. It was found that the porosity ratio of grid fabricated by gravity casting technique increased significantly compared to the grid fabricated by die-casting technique. It was also shown that ulrasonic technique is effective to evaluate the porosity ratio in positive grid.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.8
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• pp.1339-1347
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• 1997

The automation of final inspection and tuning process in the manufacturing of electric products is hot issue now, because it is the only part that has not been wholey automized yet, mainly due to the difficulties to handle so small size of VR which is the final tuning point in the most of electric products. For the automation of this process, at first the accurate measurement of position and orientation of SMD VR on PCB in real time is strongly needed. In this paper, a new image processing algorithm to detect the center position and orientation of target VR by using machine vision is proposed for automatic final tuning of the 8mm camcoder's performance. In the method, the outline feature of object is used actively. The usefulness of the proposed methods were tested by several experiments, and the results showed enough accuracy for both of position and orientation. Additatively, we discussed about the total visual system construction and preprocessing of image.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.11
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• pp.134-141
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• 2003

An industrial product is designed and fabricated, followed by the inspection process in order to check whether it is dimensionally tolerable or not. The machining process produces a part such as a mold or die, in which the three-dimensional coordinate might be measured by a CMM (Coordinate Measuring Machine) for assessment of its dimension. It is not ignorable, however, that a CMM measurement requires a lot of operating time and cost, which has led to many studies on the OMM system. The OMM system can be categorized into contact and non-contact types, and each of which has its own strengths and weaknesses. Non-contacting types generally utilize structured lights, sounds or magnetic fields. Though they show rather poor performance in positional accuracy, the measuring speed is faster than the contacting probes. This paper presents the development of an OMM system based on a non-contacting laser displacement sensing apparatus and CAD model. The system is composed of software modules of center-aligning and measuring, which has been operated and verified on a NC machining center on a shop floor.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.3
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• pp.93-114
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• 2002

This paper suggests a dynamic balanced scorecard (DBSC) model employing the concept of system dynamics (SD), which could overcome the limitations inherent in the conventional balanced scorecard (BSC) and facilitate strategic learning process in organizations. The BSC has been a successful framework for measuring an organization＇s performance in various Perspectives through translating an organization＇s vision and strategy into an interrelated set of key performance indicators and specific actions. The BSC, while having significant strengths over traditional performance measurement methods, however, has its own limitations, due to its static nature, such as overlooking two-way causation between performance Indicators and neglecting the impact of delayed feedback flowing from the adoption of new strategies or policy changes. To overcome these limitations, we employs SD, a methodology for understanding complex systems where dynamic feedback among the interrelated system components significantly impact on the system outcomes. The SD simulation model in the form of DBSC we suggest in this paper would serve as a useful strategic learning tool for facilitating an organization＇s communication process through various scenario analyses as well as predicting the dynamic behavior pattern of their key performance measures over a future time frame. For the demonstration purpose, we apply the DBSC model to Korea Coal Corporation (KoCoal ) BSC case.

• Journal of Information Technology Services
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• v.12 no.3
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• pp.273-287
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• 2013

The objective of this study is to empirically develop performance evaluation measures for LIS (logistics information systems) based upon BSC (balanced scorecard) model and determine the relative importance among four perspectives of BSC using AHP (analytic hierarchy process) methodology. Above all, forty nine probable measures for evaluating LIS performance were identified through reviewing the previous research related with SCM (supply chain management), logistics management, and information systems evaluation. And then, these probable measures were examined by means of coincidence analyses using three mutually exclusive criteria(validity of content, ease of measurement and reliability of measurement). Data for conducting the coincidence analyses were collected from LIS users and LIS development personnel. As the results of the coincidence analyses, it was found that 31 ones among 49 probable performance evaluation measures theoretically derived could be qualified for LIS performance evaluation. And AHP analysis showed that the weight of each perspective was respectively as follows : 46.8% for financial perspective, 31.3% for customer perspective, 14.8% for internal business process perspective, and 7.1% for learning and growth perspective. The academic contribution of this study is that performance evaluation measures for LIS could be systematically and empirically developed on the basis of BSC. Also, the results of this study are expected to be used as a practice guideline of evaluating and improving LIS.

• Nuclear Engineering and Technology
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• v.26 no.3
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• pp.367-373
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• 1994

It is necessary to adopt a simple signal validation for avoiding the complexity of algorithm and verification in the design process of the instrumentation and control system in nuclear plants. This paper suggests a signal validation method developed on the basis of consistency checking for the multi-channel measurement system without any analytic process model. It includes a simplified algorithm for estimating the fixed bias error of each channel and a weighted averaging method. The weighting factor of each channel is updated according to its calculated bias error. The developed method has been tested to verify its performance through several input scenarios.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.864-867
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• 2003

Since the development of semiconductors, various related research has been conducted. During research, silicon diodes have been commonly used because of their simplicity and low cost in the manufacturing process. This research deals with p-n junction threshold voltages from silicon diodes due to transport current at a cryogenic temperature. At a cryogenic temperature(77K) we could get minimum current which junction threshold voltage becomes constant. This is experimented on GPIB communication and it consist of programmable current source, multimeter which gauge the threshold voltage in a very low temperature caused by transport current from 5nA to 1mA and $LN_2$(77K) for coolant. This experiment is programmed all process using Measurement studio(Lab window) tool.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.46-49
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• 2012

Gears are reliable and efficient power transmission elements. They have been widely used in all kinds of machinery. Nowadays, resource conservation energy conservation environmental improvements from the request of the compact, light weight, high efficiency, low cost Higher efficiency is required. Tooth root and bottom profiles of cylindrical gears affect bending fatigue life, but they are hard to measure with conventional gear measuring machine(GMM), because GMM is normally customized to measure only gear working flanks. The authors try to develop a new type of GMM by installing an extra 3D scanning probe and control software to measure tooth root and bottom profiles. First, in order to measure in various directions, a 3D scanning probe has been attached to the GMM developed. Next, calibration algorithm has been developed. Deviations of the calibration results are measured and it is found that systematic error must be caused by heat from driving motors. A new alternative GMM with driving motors generating less heat was designed and two GMMs are compared. Finally, 3 Dimension measurement of tooth root and bottom profiles of cylindrical gears is described.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.69-75
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• 2017

There are two types of expensive measuring instruments currently on the market shape measurement and roundness measurement instruments. As they are very expensive, from tens of millions to more than 200 million won, buying them is economically burdensome for small companies or individuals. Therefore, in order to integrate the shape and roundness measurements into a single transfer device, this study aimed to reduce the trial and error by 3D modeling and simulation, and we confirmed the feasibility of operation. Based on these outcomes, a prototype hybrid measuring instrument was fabricated. As a result of performance evaluation and comparative evaluation, we verified the feasibility of implementation and application of the hybrid measuring instrument.