• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2004년도 추계학술대회
• /
• pp.115-123
• /
• 2004

Replacement problems can be classed as either deterministic of stochastic. Deterministic problems are those in which the timing and the outcome of the replacement action are assumed to be known with certainty. Before proceeding with development of replacement models it is important to note that preventive replacement actions, that is, ones taken before equipment reaches a failed state, require two necessary conditions: (1) The total cost of the replacement must be greater after failure than before. (2) The failure rate of the equipment must be increasing. Equipment is subject to failure. On failure, one of two possible actions can be taken : repair or complete replacement of the failed equipment. In this paper, we proposed optimal overhaul, repair, replacement maintenance model with two-state.

• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.11-17
• /
• 2022

Design-bid-build (DBB) is the most common project delivery method among highway projects. State Highway Agencies (SHAs) usually apply a low-bid approach to select contractors for their DBB projects. In this approach, the Federal Highway Agency suggests SHAs heighten contractors' competition to lower bid prices. However, these attempts may become ineffective due to collusive bidding arrangements among certain contractors. One common strategy is the rotation of winning bidders of a group of contractors who bid on many of the same projects. These arrangements may also be specific to a particular region or vary in time. Despite the practices' adverse effects on bidding outcomes, an effective model to detect red-flag bidding patterns is lacking. This study fills the gap by proposing a novel framework that utilizes pattern mining techniques and statistical tests for unusual pattern detection. A case study with historical data from an SHA is conducted to illustrate the proposed framework.

• Management Science and Financial Engineering
• /
• 제15권2호
• /
• pp.53-68
• /
• 2009

In this paper, we address a problem for minimizing the number of items inspected in a back-light-unit (BLU) inspection system, which includes a K-stage inspection system, a source inspection shop, and a re-inspection shop. In order to formulate our objective, we make a steady-state flow analysis between nodes (or shops), and derive the steady-state amount of flows between nodes and defective rates by solving a nonlinear balance equation. We provide an enumeration method for determining an optimal value of K which minimizes the number of items inspected. Our methodology could be applied and extended to similar situations with slight modification.

• 품질경영학회지
• /
• 제35권1호
• /
• pp.24-34
• /
• 2007

This paper investigates the average run length (ARL) of a selectively moving average (S-MA) control chart. The S-U chart is designed to detect shifts in the process mean. The basic idea of the S-MA chart is to accumulate previous samples selectively in order to increase the sensitivity. The ARL of the S-MA chart was shown to be monotone decreasing with respect to the decision length in a previous research [3]. This paper derives the steady-state ARL in a closed-form and shows that the monotone property is resulted from head-start assumption. The steady-state ARL is shown to be a sum of head-start ARL and an additional term. The statistical design procedure for the S-MA chart is revised according to this result. Sensitivity study shorts that the steady-state ARL performance is still better than the CUSUM chart or the Exponentially Weighted Moving Average (EWMA) chart.

• 국제학술발표논문집
• /
• The 3th International Conference on Construction Engineering and Project Management
• /
• pp.263-271
• /
• 2009

This study reveals the status, perceptions, and future directions associated with green building within construction-related companies. A survey research method was used to capture current experience levels and capabilities of companies with regard to green construction. Expectations and perceptions about the future of the construction industry with regard to green building were obtained from construction-related companies recruiting from the Myers-Lawson School of Construction at Virginia Tech from 2006 and 2008. The findings of this study support the growing importance of green building as a component of the whole construction market and provide a benchmark against which to measure future changes in the industry over time.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
• /
• pp.660-667
• /
• 2003

In this study, a Multiple Objective Mixed Integer Programming (MOMIP) Model is developed for sewer rehabilitation planning by considering cost, inflow/infiltration. A sewer rehabilitation planning model is required to decide the economic life of the sewer by considering trade-off between cost and inflow/infiltration. And it is required to find the optimal rehabilitation timing, according to the cost effectiveness of each sewer rehabilitation within the budget. To develop such a model, a multiple objective mixed integer programming model is formulated based on network flow optimization. The network is composed of state nodes and arcs. The state nodes represent the remaining life and the arcs represent the change of the state. The model consider multiple objectives which are cost minimization and minimization of inflow/infiltration. Using the multiple objective optimization, the trade-off between the cost and inflow/infiltration is presented to the planner so that a proper sewer rehabilitation plan can be selected.

• 정보처리학회논문지A
• /
• 제18A권4호
• /
• pp.135-142
• /
• 2011

본 연구는 플래시 메모리 기반의 고성능 SSD (Solid State Disk) 구조를 위하여 디스크 참조 특성에 적응적으로 구동하는 효율적인 버퍼 구조와 구동 기법을 설계한다. 기존 SSD는 삭제동작 횟수의 제약은 물론 읽기와 쓰기 동작에 대하여 비대칭적인 성능을 보이는 특징을 갖고 있다. 이러한 삭제동작 횟수와 쓰기 동작의 지연시간을 최소화 하기 위해서는 다중 플래시 메모리 칩들에 대해 쓰기 동작은 병렬적으로 수행하는 정도를 최대화하여 운영하여야 한다. 따라서 플래시 메모리 칩들에 대한 인터리빙 레벨 (interleaving level)을 최대화 하기 위하여, 본 논문에서는 혼합 위치 사상 기법 (hybrid address mapping)과 슈퍼 블록 (super-block) 기반의 SSD 구조에 대하여 성능 증대와 증가된 장치 수명을 제공하기 위한 효율적 버퍼 구조를 제안한다. 제안한 버퍼구조는 응용 수행특성을 기반으로 최적의 임의/순차쓰기를 구분하며, 수행 성능에 중요한 순차쓰기 정도의 크기를 증대시키는 동적 융합 방법, 구동되는 버퍼구조와 사상 테이블의 효율적인 관리 구조를 설계하였으며, 이를 통해 기존의 단순한 버퍼 운영기법에 비하여 35%의 성능향상을 제공한다.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 1992년도 춘계공동학술대회 발표논문 및 초록집; 울산대학교, 울산; 01월 02일 May 1992
• /
• pp.533-544
• /
• 1992

한 제품의 구성 부품 수가 증가함에 따라 조립/분해 순서의 방법수는 기하급수적으로 증가한다. 또한 이 순서의 선택에 의하여 조립/분해의 효율성이 결정된다. 본 논문에서는 조립제품의 조립순서(Assembly Sequence)와 특정부품의 효율적 교체(Part Replacement)를 위한 분해순서(Disassembly sequence)에 관한 새로운 Algorithm들을 다음 3가지 경우를 통하여 소개한다 : 1) Full Assembly/Disassembly, 2) Part Replacement by Individual Disassembly, 그리고 3) Part Replacement by Group Disassembly. 이들 Algorithm들은 'Freedom and Interference Space'라는 새로운 개념으로부터 유도되며, Group Disassembly는 Carpenter's Approach를 통하여 실현된다. 이 논문에서 소개되는 Algorithm들은 조립/분해순서와 함께 조립/분해 방향도 제시하는데 비교적 복잡한 예를 통하여 이들을 실현함으로써 실제 제품 Design에의 활용 가능성을 보여준다.

• 한국자동차공학회논문집
• /
• 제25권1호
• /
• pp.116-126
• /
• 2017

We suggest a process for the basic software configurations and application development in the mode management design of AUTOSAR-based ECU. Mode management is an essential task and AUTOSAR provides the mode management components for the runtime state handling of an ECU, such as BswM, application mode manager and RTE. BswM is used to meet the custom's requirements for ECU state handling. The behavior of BswM is configured with a set of rules in the form of "if-else" statements, so it is a complicated job and a potential source of errors as the number of rules increases. These difficulties can be overcome using the Model-Based Development approach, which is widely used in the AUTOSAR SW development. An efficient process is proposed to apply the MBD approach to the BswM configuration. An application mode development process is also proposed to improve the mode management design by combining the MBD process. Development tools are developed to adapt these proposed processes to the traditional ones. Simulation and experimental results are provided to prove the feasibility of the proposed approach.

• 기록학연구
• /
• 제7호
• /
• pp.3-35
• /
• 2003

The aim of this study is to discuss the significance of standards in general as well as that of records management in particular. It also analyzes the current state of standardization efforts that will directly and indirectly affect records management practices. It begins with introducing definitions of standards and the rationale behind the expensive and cumbersome process of standardization. Also covered are major standard-setting organizations at different levels such as international and national level and various types of standards created or endorsed by these organizations. Throughout the study, main focus is given to standards and standardization endeavors in records management. Until recently, standardization activities have been mainly concentrated on manufacturing industry. Consequently, standards regarding records management are not sufficient enough to satisfy organizational and professional needs. Even ISO/TC 46/ SC 11, which is in charge of standardization in records management at the international level, has just published one standard, ISO 15489 : 2001 and newly proposed five standards in 2002. Awareness of the current state calls for active participation of records managers to the standard-related activities as discussed in this study. It is also asked to keep up with the global movement by establishing standards tailored to Korean situations as well as by actively participating In international standardization activities In order to take an initiative at the international level.