• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.110-113
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• 2008

This study was performed to predict the shape of polymer extrusion product and to find the cause of defective products Experiments was performed to extrude the complex profile shape using PC/ABS composite resin with new profile die and cooling die. A finite element analysis for the Polymer Extrusion process considering the heat transfer and thermal deformation was also performed, and the result was compared with the experimental data. It is found that the predicted profile shape in F. E. M was similar to the experimental result and the thickness of extruded product was thin when the velocity of profile die outlet was slow than the velocity of production (2m/min).

• 품질경영학회지
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• 제23권3호
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• pp.140-155
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• 1995

This paper proposes a quality control method of assembly parts based on parts inspection information. We use the parts inspection information for reduction of defective fraction in assembly and prediction of assembly quality. At first, we build the functional relationship between parts and assembled unit by regression analysis. Secondly, if we use the inspection informations of parts which are estimators of means and variances, we can predict the nonconforming probability of assembled unit and propose the best assembly method. In a case study, we showed the efficency of the proposed method in two part assembly.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.172-175
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• 2008

In the last five years, 45 people died and 104 were wounded because of carbon monoxide poisoning accident. CO poisoning accident is higher than any other gas accident in the rate of deaths/incidents. Most of these CO poisoning accidents were caused by defective exhaust tube in the old gas boiler and multi-use facility. In this study, the spread of CO gas released from leakage hole of exhaust tube was analyzed by computational flow modeling and concentration measuring test. CO gas leaked form exhaust tube in a building was highest concentrated near the ceiling and formed the circular currents along the walls. Through these experiments and simulation, the reasonable installation location of CO alarm was made certain and suggested.

• 한국신뢰성학회지:신뢰성응용연구
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• 제8권2호
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• pp.87-100
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• 2008

The rubber fender is used to absorb the berthing energy that is produced when a ship is near a port, and it prevents collision between the ship and port. If the rubber fender becomes defective, the berthing energy cannot be absorbed when it is near the port, and damage can result from collisions due to the hardening process. In this research, when the rubber fender is heated, collisions can cause cracks and other damage. It is also confirmed from the research the lifetime distribution of the rubber fender. The researcher has predicted using different variables and elongation that a rubber fender has an 11year lifespan at $20^{\circ}C$.

• 정보저장시스템학회논문집
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• 제2권1호
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• pp.56-64
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• 2006

This paper proposes a new and simple input prediction method for robust servo system. A robust tracking control system for optical disk drives to reject disk runout was recently proposed based on both Coprime Factorization(CF) and Zero Phase Error Tracking(ZPET) control. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness to parameter uncertainties and disturbance rejection capability. Since optical disk tracking servo systems can detect only racking error, it was proposed that the reference input signal for ZPET could be estimated from tracking errors. In this paper, we propose a new control structure for the ZPET controller. It requires less memory than the previously proposed method for the reference signal generation. Therefore, it is very effective in runout control. Furthermore, this method can be applied to defective optical disk like surface defects on disk. Numerical simulation and experimental result show the proposed method effective.

• Design & Manufacturing
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• 제13권3호
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• pp.29-34
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• 2019

Cell phone injection is characterized by its small size and thinness. In addition, the product has a short cycle time, requiring a very short production schedule. To produce more accurate products faster, data from experience in producing similar products is required. In this study, two mobile phone models are presented. In this study, the quality problems caused by molding analysis and actual injection molding were analyzed and made into a database. As a result, it was considered that all the defects in the molding analysis do not affect the product in some cases, rather than appear as defects in the actual product. All defects shown in the molding analysis can be made into a database, and based on this data, it will be possible to obtain an effect that can predict more accurately whether it will cause problems after injection.

• 플랜트 저널
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• 제8권3호
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• pp.49-54
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• 2012

현재 운영 중인 발전소 전동기의 고정자 권선 고장 실제사례를 토대로 전동기에서 발생하는 자속 데이터의 고주파 영역 스펙트럼을 분석함으로써 결함이 있는 전동기와 건전한 전동기의 자속 특성 및 변화추이를 분석하였다. 전동기 자속스펙트럼의 고주파 영역을 분석한 결과 결함이 있는 전동기는 고정자 슬롯 주파수 대비 고정자 슬롯 사이드밴드 주파수의 상대적 크기 비율이 건전한 전동기에 비해 매우 높음을 확인하였다. 또한 결함이 있는 전동기는 시간이 지날수록 고정자 슬롯 주파수 대비 고정자 슬롯 사이드밴드 주파수의 상대적 크기 비율 크기도 더욱 커지는 현상도 확인하였다. 그리고 결함이 있는 전동기의 자속 데이터는 불시 고장 1개월여 전부터 결함 상태를 인식할 수 있는 신호를 나타냄으로써 전동기 고정자 권선 결함에 대한 사전 예측능력이 매우 탁월함을 확인하였다.

• Macromolecular Research
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• 제16권1호
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• pp.15-20
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• 2008

The enhanced permeability and retention (EPR) effect is used extensively for the passive targeting of many macromolecular drugs for tumors. Indeed, the EPR concept has been a gold standard in polymeric anticancer drug delivery systems. This study investigated the tumoral distribution of self-assembled nanoparticles based on the EPR effect using fluorescein and radio-labeled nanoparticles. Self-assembled nanoparticles were prepared from amphiphilic chitosan derivatives, and their tissue distribution was examined in tumor-bearing mice. The size of the nanoparticles was controlled to be 330 run, which is a size suited for opening between the defective endothelial cells in tumors. The long-circulating polymer nanoparticles were allowed to gradually accumulate in the tumors for 11 days. The amount of nanoparticles accumulated in the tumors was remarkably augmented from 3.4%ID/g tissue at 1 day to 25.9%ID/g tissue at 11 days after i.v. administration. The self-assembled nanoparticles were sustained at a high level throughout the 14 day experimental period, indicating their long systemic retention in the blood circulation. The ${\gamma}$-images provided clear evidence of selective tumor localization of the $^{131}I$-labeled nanoparticles. Confocal microscopy revealed the fluorescein-labeled nanoparticles to be preferentially localized in the perivascular regions, suggesting their extravasation to the tumors through the hyperpermeable angiogenic tumor vasculature. This highly selective tumoral accumulation of nanoparticles was attributed to the leakiness of the blood vessels in the tumors and their long residence time in the blood circulation.

• 대한기계학회논문집A
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• 제37권8호
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• pp.975-981
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• 2013

강건 최적화 기법은 설계 초기 단계부터 설계변수의 변동이 목적함수에 미치는 효과를 최소화할 수 있는 유일한 방법이다. 강건 최적화의 정식화를 위해서는 분산을 정확히 예측하고 확률제한조건을 정식화하는 것이 가장 중요한 과정이 된다. 분산 및 확률제한조건을 예측하고 정식화하기 위한 방법으로 공정능력지수 및 식스시그마 기법과 같은 여러 가지 방법이 적용되고 있으나, 실제 공정에서 널리 적용되는 불량률을 이용한 확률제한조건 처리 기법에 대한 연구는 아직까지 전무한 상태이다. 본 연구에서는 자동차 로워암의 무게와 최대응력의 평균과 표준편차에 대한 설계영역을 탐색하고, 이후 로워암의 강건 최적화를 수행하였다. 변동을 예측하기 위한 표준편차의 계산은 2 차 테일러 전개를 통해 수치적인 정확도를 기하였다. 강건 최적화는 설계변수의 불연속성을 고려하기 위하여 최적화 과정에서 미분 정보를 적용하지 않은 심플렉스 알고리즘을 적용하였다.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제7권3호
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• pp.77-90
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• 2018

소프트웨어 결함 예측(SDP)은 결함이 있는 모듈을 식별하기 위한 연구 분야이다. 충분한 로컬 데이터가 없으면 다른 회사에서 수집한 데이터를 사용하여 분류기를 구축하는 교차 프로젝트 결함 예측(CPDP)을 활용할 수 있다. SDP에 대한 대부분의 기계 학습 알고리즘은 서로 다른 값에 따라 예측 성능에 큰 영향을 미치는 하나 이상의 매개 변수를 사용한다. 본 연구의 목적은 CPDP의 예측 성능 향상을 위해 매개 변수 선택 기법을 제안하는 것이다. Harmony Search 알고리즘을 사용하여, 예측 어려움을 야기하는 클래스 불균형을 해결하는 방법인 비용에 민감한 부스팅의 매개 변수를 조정한다. 분포 특성에 따라 매개 변수 범위와 매개 변수 간의 제한 조건 규칙이 정의되어 하모니 검색 알고리즘에 적용된다. 제안된 접근법은 15개의 대상 프로젝트를 대상으로 3개의 CPDP 모델과 내부프로젝트 결함 예측(WPDP) 모델을 비교한다. 실험 결과는 제안된 방법이 클래스 불균형의 맥락에서 다른 CPDP 방법보다 성능이 우수하다는 것을 보여준다. 이전의 연구에서는 탐지 확률이 낮거나 오보 가능성이 높았으나 우리의 기법은 높은 PD와 낮은 PF를 제공하면서 높은 전체 성능을 보였다. 또한 WPDP와 비슷한 성능을 제공하였다.