휴대폰용 카메라 모듈의 렌즈 시스템에 대한 공차 해석 및 설계 개선에 관한 연구

정상진(Sangjin Jung),최병렬(Byung-Lyul Choi),최동훈(Dong-Hoon Choi),김주호(Ju Ho Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

A lens system of a camera module for mobile phones is comprised of the composition and design of various shapes of lens. To improve responses such as the modular transfer function (MTF), a lens system should always be constructed by considering uncertainty that can be caused by manufacturing and assembly error. In this study, tolerance optimization using the Latin Hypercube Sampling (LHS) technique is performed. In order to reduce the computational burden of the tolerance optimization process and decrease the influence from numerical noise effectively, we use the Progressive Quadratic Response Surface Modeling (PQRSM), which is one of Sequential Approximate Optimization (SAO) techniques. Using this method, we achieved optimal tolerance for each lens and obtained reliability for satisfying user’s requirements. In addition, through the design process the manufacturing and assembly cost of a lens system was reduced.

비균일 수렴허용오차 방법을 이용한 분지한계법 개선에 관한 연구

정상진(Sangjin Jung),Xi Chen,최경현(Gyunghyun Choi),최동훈(Dong-Hoon Choi) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.4

혼합이산비선형계획법(mixed-discrete nonlinear programming) 문제의 최적화를 위한 대표적인 기법 중에 하나인 분지한계법(branch-and-bound method)은 다른 기법에 비해 강건하지만 분지한계법 내부의 각 노드마다 연속 최적화를 수행해야 하기 때문에 많은 함수 계산이 요구되는 것으로 알려져 있다. 이러한 분지한계법의 단점을 극복하기 위하여 크게 두 가지 연구를 수행하였다. 먼저, 분지한계법의 각 노드마다 동일한 수렴허용오차를 설정해주던 기존의 방법을 대체할 수 있는 비균일 수렴허용오차 방법을 제안하였다. 또한 분지한계법에 적용할 수 있는 5 가지 분지순서 방법 중에서 분지한계법의 성능을 가장 극대화할 수 있는 분지순서 방법을 제시하였다. 수렴허용오차 방법과 분지순서 방법들을 각각 선택하여 분지한계법에 적용한 후 7 개의 수학예제와 4 개의 공학예제에 대하여 테스트를 수행한 결과, 제안된 비균일 수렴허용오차 방법과 5 가지 분지순서 방법 중 최소간격차이법을 분지한계법에 함께 적용할 경우 분지한계법의 성능이 가장 극대화 됨을 확인할 수 있었다. In order to improve the efficiency of the branch-and-bound method for mixed-discrete nonlinear programming, a nonuniform convergence tolerance scheme is proposed for the continuous subproblem optimizations. The suggested scheme assigns the convergence tolerances for each continuous subproblem optimization according to the maximum constraint violation obtained from the first iteration of each subproblem optimization in order to reduce the total number of function evaluations needed to reach the discrete optimal solution. The proposed tolerance scheme is integrated with five branching order options. The comparative performance test results using the ten combinations of the five branching orders and two convergence tolerance schemes show that the suggested non-uniform convergence tolerance scheme is obviously superior to the uniform one. The results also show that the branching order option using the minimum clearance difference method performed best among the five branching order options. Therefore, we recommend using the “minimum clearance difference method” for branching and the “non-uniform convergence tolerance scheme” for solving discrete optimization problems.

훈련기 고장 다빈도 품목의 체계 영향성 분석 연구

정상진(Sangjin Jung),봉주성(Jusung Bong),백일호(Ilho Baek),허장욱(Jangwook Hur) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.1

Purpose: An improved target operational availability is required to maintain the combat readiness of a trainer plane. This study investigates the improvements in the failure rate of the trainer plane and its effect on the reliability, availability, and maintenance cost. Methods: The flight control system has an improved failure rate with a higher mean time between failure (MTBF) value. It is necessary to improve the failure rates of other subsystems, to meet the target operational availability. Results: The results improved the failure rate of items with frequent failures to meet the target operational availability of the trainer. Specifically, the operational availability and MTBF were improved by 8.6% and 194.4%, respectively. However, the propsed methed can reduce failure rates and operating maintenance costs by 45.3% and 34.3%, respectively. Conclusion: As a method of improving the target operational availability required for maintaining the combat readiness of the trainer, the impact on the reliability, availability, and operation maintenance cost of the trainer was analyzed when improving the failure rate of items with frequent failures.

휴대폰용 카메라 렌즈 시스템의 공차최적설계

정상진(Sangjin Jung),최동훈(Dong-Hoon Choi),최병렬(Byung-Lyul Choi),김주호(Ju Ho Kim) (사)한국CDE학회 2011 한국CDE학회 논문집 Vol.16 No.6

Since tolerance allocation in a mobile phone camera manufacturing process greatly affects production cost and reliability of optical performance, a systematic design methodology for allocating optimal tolerances is required. In this study, we proposed the tolerance optimization procedure for determining tolerances that minimize production cost while satisfying the reliability constraints on important optical performance indices. We employed Latin hypercube sampling for evaluating the reliabilities of optical performance and a function-based sequential approximate optimization technique that can reduce computational burden and well handle numerical noise in the tolerance optimization process. Using the suggested tolerance optimization approach, the optimal production cost was decreased by 30.3 % compared to the initial cost while satisfying the two constraints on the reliabilities of optical performance.

휴대폰 카메라용 렌즈 시스템의 강건최적설계

정상진(Sangjin Jung),민준홍(Jun-Hong Min),최동훈(Dong-Hoon Choi),김주호(Ju Ho Kim) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1

A lens system for mobile phone cameras is comprised of various lenses and designed in order to satisfy design requirements for responses such as a modular transfer function (MTF). However, it is difficult to manufacture and assemble camera modules to maintain the same performance compared with the designed camera modules, because of uncertainty. We should always design a lens system by considering uncertainty that can be caused by errors in the manufacturing and assembly process of mobile phone cameras. The robust optimization offers tools of making robust decisions with the consideration of design parameters, uncontrollable parameters, and the variance of the system. Using an efficient reliability analysis method and an optimization algorithm, we obtained robust optimization results that maximize the mean of MTF and minimize the standard deviation and proposed a new robust design process for a lens system.

가격경직성과 산업연관관계

정상진(Sangjin Jung),정우식(Woo S. Jung) 한국계량경제학회 2003 계량경제학보 Vol.14 No.4

본 논문은 산업수준에서의 가격경직성과 투입산출표에 나타나는 산업연관의 특징 간의 관계에 대한 이론 및 실증분석이다. 본 논문의 이론에 의하면 다수의 투입물 공급자 및 생산물 수요자와 거래하는 독점적 경쟁기업은 가격조정을 할 때마다 발생하는 메뉴비용과 가격조정에서 오는 이득을 서로 상쇄시키면서 그 이윤을 극대화한다. 이 경우 상위 가공단계 산업 및 하위가공단계 산업과의 직접적인 연관관계가 증가할수록 가격이 더욱 빈번히 조정된다. 본 논문의 실증분석은 이론의 예측을 지지한다. 실증분석은 미국 주요 산업의 가격경직성 정도와 투입산출표에 나타난 산업들의 연관도 간의 관계를 조사하여 가격경직성에 대한 새로운 실증적 증거를 제시한다. 따라서 사용된 시계열 및 횡단면 표본데이터는 산업들의 가격조정비용의 성격과 가격경직성에 대한 새 케인스 경제학적인 설명을 지지한다. The present study provides a needed theoretical and empirical examination of the relationship between the stickiness of price adjustment at the industry level, and the input-output table characterization of inter-industry linkages. According to the theory, the higher linkage an industry has with other upstream input-supply industries and other downstream output-demand industries, the more frequently the industry will tend to change its prices. Monopolistically competitive firms facing large numbers of input suppliers and output demanders tend to trade off the benefit of more frequent price adjustments against the menu cost they have to incur each time they change prices. The empirical part of this paper presents new empirical evidence on price stickiness by examining the relationship between the degree of price stickiness in major U.S. industries and their underlying characteristics manifest in the economy-wide input-output table. Therefore our sample of time-series and cross-section data supports the New Keynesian explanation of the nature of the adjustment cost and the stickiness of price setting across industries.

대규모 실감형 제품설계 플랫폼 프로토타입 시스템에의 설계 최적화 모듈 통합 방안

정상진(Sangjin Jung),최평민(Pyung-Min Choi),최동훈(Dong-Hoon Choi),김재성(Jaesung Kim),이상민(Sang Min Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4

휴대폰 카메라용 렌즈 시스템의 강건최적설계

정상진(Sangjin Jung),민준홍(Junhong Min),최동훈(Dong-Hoon Choi),김주호(Ju Ho Kim) (사)한국CDE학회 2010 한국CDE학회 논문집 Vol.15 No.5

A lens system for mobile phone cameras is comprised of various lenses and designed so as to satisfy design requirements for responses such as a modular transfer function (MTF). However, it is difficult to manufacture and assemble camera modules to maintain the same performance compared with the designed camera modules, because of uncertainty. We should always design a lens system by considering uncertainty that can be caused by errors in the manufacturing and assembly process of mobile phone cameras. The robust optimization offers tools of making robust decisions with the consideration of design parameters, uncontrollable parameters, and the variance of the system. Using an efficient reliability analysis method and an optimization algorithm, we obtained robust optimization results that maximize the mean of MTF and minimize the standard deviation and proposed a new robust design process for a lens system.

무단변속기 소음 개발에 관한 연구

차정권(Jungkwon Cha),정상진(Sangjin Jung),최장원(Jangwon Choi),이희용(Heeyong Lee) 한국자동차공학회 2018 한국자동차공학회 학술대회 및 전시회 Vol.2018 No.11

This paper shows a whole noise developing procedure and items for the new developed Mid-CVT. Through the case FRF test, the robust design of the CVT was investigated. To reduce the planetary gear noise, the gear tooth-contact pattern test was performed. Through the gear tooth-contact pattern test, the new specification was developed. And all gear grinding methods are also used. Due to demands for reducing the serious abnormal chain-belt noise some special test method are developed and applied. Though the control of guiderail length and chain pitch length, chain-belt noise could be handled and reduced effectively. The whole developing process and results will offer good guides to the engineers who develop the new CVT.

자동변속기 강성 보강을 통한 기어 소음 저감

차정권(Jungkwon Cha),정상진(Sangjin Jung),조명수(Myungsoo Cho),최인혁(Inhyuk Choi) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11

Reduction of planetary gear noise for the automatic transmission was investigated using dynamic stiffness strengthening of the transmission case and the mounting bracket. Dynamic stiffness of case was improved by the reinforcing rib and shape change, through the FRF test, and 1’st mode frequency was also improved by the shape change of vehicle mounting bracket. After that, noise reduction was confirmed by the comparing before and after vibration and noise level of automatic transmission at the anechoic chamber and vehicle. Test results show that gear noise of transmission was improved 10dB at anechoic chamber and 8dB reduced in vehicle noise respectively.