• 지능정보연구
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• 제23권1호
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• pp.47-67
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• 2017

강판 표면 결함은 강판의 품질과 가격을 결정하는 중요한 요인 중 하나로, 많은 철강 업체는 그동안 검사자의 육안으로 강판 표면 결함을 확인해왔다. 그러나 시각에 의존한 검사는 통상 30% 이상의 판단 오류가 발생함에 따라 검사 신뢰도가 낮은 문제점을 갖고 있다. 따라서 본 연구는 Simultaneous MTS (S-MTS) 알고리즘을 적용하여 보다 지능적이고 높은 정확도를 갖는 새로운 강판 표면 결함 진단 시스템을 제안하였다. S-MTS 알고리즘은 단일 클래스 분류에는 효과적이지만 다중 클래스 분류에서 정확도가 떨어지는 기존 마할라노비스 다구찌시스템 알고리즘(Mahalanobis Taguchi System; MTS)의 문제점을 해결한 새로운 알고리즘이다. 강판 표면 결함 진단은 대표적인 다중 클래스 분류 문제에 해당하므로, 강판 표면 결함 진단 시스템 구축을 위해 본 연구에서는 S-MTS 알고리즘을 채택하였다. 강판 표면 결함 진단 시스템 개발은 S-MTS 알고리즘에 따라 다음과 같이 진행하였다. 첫째, 각 강판 표면 결함 별로 개별적인 참조 그룹 마할라노비스 공간(Mahalanobis Space; MS)을 구축하였다. 둘째, 구축된 참조 그룹 MS를 기반으로 비교 그룹 마할라노비스 거리(Mahalanobis Distance; MD)를 계산한 후 최소 MD를 갖는 강판 표면 결함을 비교 그룹의 강판 표면 결함으로 판단하였다. 셋째, 강판 표면 결함을 분류하는 데 있어 결함 간의 차이점을 명확하게 해주는 예측 능력이 높은 변수를 파악하였다. 넷째, 예측 능력이 높은 변수만을 이용해 강판 표면 결함 분류를 재수행함으로써 최종적인 강판 표면 결함 진단 시스템을 구축한다. 이와 같은 과정을 통해 구축한 S-MTS 기반 강판 표면 결함 진단 시스템의 정확도는 90.79%로, 이는 기존 검사 방법에 비해 매우 높은 정확도를 갖는 유용한 방법임을 보여준다. 추후 연구에서는 본 연구를 통해 개발된 시스템을 현장 적용하여, 실제 효과성을 검증할 필요가 있다.

• 보건행정학회지
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• 제2권2호
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• pp.112-130
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• 1992

Patient care services are provided to individual patients in response to their health needs produced by illnesses or injuries. The services are often addressed to very serious conditions, and also they constitute the most expensive component of health care services. Therefore, the importance of quality is emphasized, but there are many indications that patient care quality is far from a satisfactory state in most of the countries. Based upon this observation, it is attempted to examine obstacles and approaches to quality improvement in patient care services. In doing so, following Taguchi's(1986) definition of product quality, quality of patient care services is conceived of as better when the less is the sociental loss attributalbe to variability of intended function and harmful side effects they emhibit after being delivered. Some distinguishing features of medical care sector pose difficulties in implementing effective quality improvement programs in patient care services. Nevertheless, newly proposed method of quality management, based on industrial quality management approach, seems to have a great deal of potential to effectively cope with such difficulties. This method, unlike the traditional approach to quality assurance, focuses on total organisational processes, not individuals, as the obproach to quality assurance, focuses on total organizational processes, not individuals, as the objects of quality improvement; variation, not comparison with standards, in quality measurement; and continuous improvement, not removing only bad quality care, as an ideal. Prerequisite to a successful use of any quality mangement method is motivating providers to improve quality. Conceivable approaches for such motivation are self-regulation, external controls and promotion of competition. Since these approaches are not mutually exclusive, they may be employed in an appropriate combination. In Korea, medical care providers are now functioning under the circumstances where they have little reason for making efforts to improve quality of their services. Once these circumstantial conditions are changed to exert pressures on providers to improve quality, the use of adequate quality management method becomes an issue. In this connection, much attention shoould be directed to the newly proposed method described above. In all these efforts for improving quality of patient care services, health insurance would be able to play a pivotal role. Poviders of medical care, buth indiciduals and organizations, are usually very responsive to the measures that affect their financing, and thus health insurance can be a strong instrument for motivationg providers to improve quality. Also, the insurance continuously acquires data on patient care, which could be processed to produce information required to effective quality control.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.285-288
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• 2007

The use of commercial finite element analysis software to perform the entire process analysis and springback analysis has increased fast for last decade. Pamstamp2G is one of commercial software to be used widely in the world but it has still not been perfected in the springback prediction accuracy. We must select the combination of input parameters for the highest springback prediction accuracy in Pamstamp2G because springback prediction accuracy is sensitive to input parameters. Then we study the affect of input parameters to use member part for acquiring high springback prediction accuracy in Pamstamp2G. First, we choose important four parameters which are adaptive mesh level at drawing stage and cam flange stage, Gauss integration point number through the thickness and cam offset on basis of experiment. Second, we make a orthogonal array table L82[(7)] which is consist of 8 cases to be combined 4 input parameters, compare to tryout result and select main factors after analyzing affect factors of input parameters by Taguchi's method in 6 sigma. Third, we simulate after changing more detail the conditions of parameters to have big affect. At last, we find the best combination of input parameters for the highest springback prediction accuracy in Pamstamp2G. The results of the study provide the selection of input parameters to Pamstamp2G users who want to Increase the springback prediction accuracy.

• 대한기계학회논문집A
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• 제36권3호
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• pp.347-353
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• 2012

최근 휴대폰은 스마트폰의 출연으로 다기능화가 요구되고 있으며, 각 보드의 전기적 신호를 연결시키는 커넥터는 필수 핵심 부품이 되었다. 커넥터는 많은 양의 전기신호를 처리하기 때문에 소형화, 협피치화가 필요하다. 하지만, 커넥터의 소형화 및 협피치화는 구조적 안전성을 저하시키며, 외부하중에 의한 접촉불량을 발생시킨다. 따라서 본 논문에서는 초소형 협피치 FPC 커넥터를 개발하기 위해 벤치마킹을 통한 초기설계안을 도출하였으며, 터미널 두께 0.2mm, 개수 50 개를 기준으로 하였다. 체결성능을 평가하기 위해 수치해석 모델을 구성하였으며, 다구찌 방법을 이용하여 형상 최적화를 수행하였다. 또한, 터미널의 한계수명을 예측하기 위해 피로해석을 수행하였으며, 체결 성능이 향상된 최종형상을 도출하였다.

• 한국재료학회지
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• 제25권9호
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• pp.442-449
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• 2015

The effects of coating parameters were investigated in wear resistance coatings of Diamalloy-406 on Inconel 718 to obtain an optimum coating condition by high velocity oxy-fuel spraying. The coating parameters, the flow rates of source gases (hydrogen and oxygen), the powder feed rate, and the spray distance, were designed by the Taguchi method. The optimal conditions were determined: oxygen flow rate 34 FRM, hydrogen flow rate 57 FRM, powder feed rate 35 g/min, and spray distance 7 inch. Friction coefficients of the coating and the substrate decreased with an increasing sliding surface temperature from $25^{\circ}C$ to $450^{\circ}C$. The friction coefficient of Diamalloy-4006 coating decreased as the sliding surface temperature increased from $0.43{\pm}0.01$ at $25^{\circ}C$ to $0.29{\pm}0.01$ at $450^{\circ}C$. The wear trace and wear depth of the coating were smaller than the substrate at all temperatures tested. The relationship between spray parameters and wear resistance was discussed extensively, based on the measured roughness, hardness, and porosity in each coating.

• 한국산학기술학회논문지
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• 제12권3호
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• pp.1051-1057
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• 2011

최근 개발된 GMP공정의 활용으로 디지털 카메라, 광저장기기, 각종 전자기기 등의 광응용 기기에서 비구면 유리렌즈가 폭넓게 활용되고 있다. GMP공정은 복잡한 형상의 유리렌즈를 정밀하면서도 경제적으로 생산할 수 있다. 본 연구에서는 다구치 실험계획법을 이용하여 순차이송형 GMP공정에서 비구면 유리렌즈의 성형 조건을 최적화 하였다. 냉각 1단계에서의 압력과 온도, 시간을 3가지 주요 공정변수로 정하였으며, 3캐비티 금형을 이용하여 실험한 결과 순차이송형 유리렌즈 성형공정에서 냉각시간이 비구면 유리렌즈의 형상정밀도(PV)에 가장 큰 영향을 미치는 것을 알 수 있었다.

• 한국재료학회지
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• 제20권9호
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• pp.494-499
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• 2010

Tin oxide thin films were prepared on borosilicate glass by rf reactive sputtering at different deposition powers, process pressures and substrate temperatures. The ratio of oxygen/argon gas flow was fixed as 10 sccm / 60 sccm in this study. The structural, electrical and optical properties were examined by the design of experiment to evaluate the optimized processing conditions. The Taguchi method was used in this study. The films were characterized by X-ray diffraction, UV-Vis spectrometer, Hall effect measurements and atomic force microscope. Tin oxide thin films exhibited three types of crystal structures, namely, amorphous, SnO and $SnO_2$. In the case of amorphous thin films the optical band gap was widely spread from 2.30 to 3.36 eV and showed n-type conductivity. While the SnO thin films had an optical band gap of 2.24-2.49 eV and revealed p-type conductivity, the $SnO_2$ thin films showed an optical band gap of 3.33-3.63 eV and n-type conductivity. Among the three process parameters, the plasma power had the most impact on changing the structural, electrical and optical properties of the tin oxide thin films. It was also found that the grain size of the tin oxide thin films was dependent on the substrate temperature. However, the substrate temperature has very little effect on electrical and optical properties.

• Journal of Welding and Joining
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• 제27권3호
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• pp.38-43
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• 2009

The optimization of the welding parameters was studied to maximize the weldability and minimize the amount of spatter in the MAG welding of automotive steel sheets under different shielding gas composition ratio. JS-EFSC, JS-SPHC steel plates and Ar mixture gases were used as a substrate and shielding gas for welding respectively. The five welding parameters were selected through preliminary experiments and their effects on the weldability were analyzed. Experiments were performed using the Taguchi experimental method. As results, appropriate range for welding could be achieved. Amount of spatter in 80%Ar+20%$CO_2$ shielding gas was 20% of that of $CO_2$welding. Therefore, in terms of high productivity and welding cost, Ar mixture gas(80%Ar+20%$CO_2$) was recommended as a shielding gas for application of MAG process, indicating the low spatter and good weld quality.

• 한국기계가공학회지
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• 제16권4호
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• pp.53-61
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• 2017

Turbocharger is a device for increasing the power of a vehicle engine. The control plate is the main component for fixing the vane of the turbocharger. Now, the control plate is made of austenite steel cutting after the casting process. It has excellent corrosion, heat resistance and mechanical characteristics of material. However, present the process is made by cutting after casting. when cutting is processed after casting, so materials, processing time, and processing energy are lost. Therefore, this study proposes a process to powder compact use of stainless steel Deklak2 and to minimize amount of cutting through net shape process. The mechanical properties of Deklak2 were verified by tensile test, hardness test and relative density measurement, and the governed equation was defined. Also, the curvature radius 1, 2 and the density, affects the shape, were selected as the design parameters, and the best process conditions was proposed through the Taguchi method and the evaluation of SN ratio. And then prototype molds were fabricated and compared with the results of the finite element analysis for the verification, and it was found that the tendency of relative density and dimension was coincided. Therefore, it was found that the amount of cutting can be minimized by only the net shape process after the sintering process and it can be applied to mass production.

• 대한기계학회논문집A
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• 제40권3호
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• pp.245-252
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• 2016

본 논문은 벤드(bend)부의 노후 문제를 경감시키기 위한 대안으로 폼패드를 없앤 이중보온관의 형상 설계를 제안하였다. 전 관경에 대해 유한요소해석을 수행하였으며, 이를 토대로 전단제어링 형상을 결정하였다. 제안된 전단제어링 사양 강화이형관에 대한 현장 시공 시험은 진행하였으며, 온도와 응력 데이터를 취득 및 분석하였다. 강화이형관의 제작과 현장 시범시공을 통하여 강화이형관이 폼패드를 시공하지 않으면서도 강관의 열응력이 허용치 기준내에 있음을 확인하였다. 특히 보온재의 전단강도가 강화되어 폼패드를 적용한 기존 벤드보다 낮은 최대 전단응력이 발생함을 확인함으로써, 강화이형관 적용에 따른 구조 안전성 향상 효과를 확인하였다.