• 한국농공학회지
• /
• 제15권4호
• /
• pp.3170-3180
• /
• 1973

This study of the subject will review past and present irrigation development in Korea. Particular attention will be given to water pricing structure and a case study on the purpose of rational operation and management of irrigation water and organizations, and the optimum irrigation water and organizations, and the optimum irrigation water fee inorder to reduce farmers burden and to rationalize the farmland associations management so as to achieve development of the rural environment. In 1971, the reservoir of the Farmland Improvement A sociation (FIA) produced only 775 millison $m^3$ of irrigation water or 77% of planned capacity of 1,015 million $m^3$. It was caused by inefficient maintenance of irrigation facilities; for instance, about 21% of reservoirs, pumping stations and weirs in Korea have been silted by soil erosion which hinder to water production according to an ADC survey. The first Irritation Association was established in 1906, whcih was renamed the Farmland Assoeiation by the Rural Development Enouragement Law in 1970. By the end of 1971, 411,000 ha of rice paddies were under the control of 267 associations nationwide. The average water price assessed by Associations nationwide rose from 790 won per 0.1 ha. in 1966 to 1,886 won in 1971. The annual growth rate was 20%. The highest water price in 1971 was 4,773 won her 0.1 ha. and the lowest was 437 won. This range was caused by differences in debt burden, geographic conditions and management efficiency among the Associations. In 1971, the number of Associations which exceeded the average water price of 1,886 won per 0.1 ha. was 144, or 55.1% of all Association. In determination of water price, there are two principles; one is determined by production cost such as installation cost of irrigation facilities, maintenance cost, management cost and depreciation ect. For instance, the Yong San River Development project was required 33.7 billion won for total construction and maintenance cost is 3.1 billion won for repayment, maintenance and management cost per year. The project produces 590 million $m^3$ of irrigation water annually. Accordingly, the water price per $m^3$ is 5.25 won. The other principle is determined by water value in the crop products and in compared with production of irrigated paddy and non-irrigated paddy. By using this method, water value in compared with paddy rice vs. upland rice(Average of 1967-1971) was 14.15 won per $m^3$ and irrigated paddy vs. non-irrigated paddy was 2.98 won per $m^3$. In contrast the irrigation fee in average association of 1967-1971 was 1.54 won per $m^3$. Accordingly, the current national average irrigation fee(water price) is resonable compared with its water value. In this study, it is found that the ceiling of water price in terms of water value is 2.98 won per $m^3$ or 2,530 won per 0.1 ha. However, in 1971 55% of the associations were above the average of nationwide irrigation fees. which shows the need for rationalization of the Association's management. In connection with rationalization of the Association's management, this study recommends the following matters. (1) Irrigation fee must be assessed according to the amount of water consumption taking intoaccount the farmer's ability. (2) Irrigation fee should be graded according to behefits and crop patterns. (3) Training personnel in the operation and procedures of water management to save O&M costs. (4) Insolvent farmland association should be integrated into larger, sound associations in the same GUN in order to reduce farmers' water cost. (5) The maintenance and repair of existing irrigation facilities is as important as expansion of facilities. (6) Establishment of a new Union of Farmland Association is required to promoted proper maintenance and to protect the huge investment in irrigation facilities by means of technical supervision and guidance.

• 산업공학
• /
• 제9권2호
• /
• pp.191-202
• /
• 1996

A variety of approaches on performance evaluation modeling have appeared in the technical literature for flexible manufacturing systems(FMS) which can be evaluated only through computer simulation. This study represents a comparative approach for FMS performance evaluation modeling based on reliability, availability and maintainability, and life cycle cost. The methodology proposed in this research includes the following three-step generative approaches. First, a static model to find the initial system configuration is considered under the assumption that the system availability is given as one (failure and maintenance are not considered), and in second step, a stochastic simulation is proposed to serve as a performance evaluation model for FMS with stochastic failure and repair time. In the last step, we developed a simulation modeling using a simulator, FACTOR/AIM to consider a variety of performance factors and dynamic behavior of FMS. Also the applicability and validity of the proposed approaches has been tested and compared through the results of a sample problem using computer programs and procedures developed in each step.

• 한국군사과학기술학회지
• /
• 제4권2호
• /
• pp.70-83
• /
• 2001

The required standards for environmental tests for communication and electronic equipment used currently in the army are not standards into which the Korean climate and use environment are taken into consideration. But the environmental testing standards of the U.S. army at the time of its establishment(MIL-STD-810) “A” version has been used without taking into consideration the Korean domestic situation and conditions by simply translating the US standards. Adherence to these standards may limit the ability to supply materials in case of emergency since the increase in the manufacturing costs according to excessively strict standards induces an increase in the acquisition cost of military equipment, unnecessarily high maintenance and repair expenses are consumed, and stocks of parts for the military use have to be retained at all times.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
• /
• pp.216-218
• /
• 1995

This paper presents the concepts developed to propose Distributed Control System(DCS). To achieve adequate satisfaction under various conditions, the DCS should be designed from two points of view of functions distributions and performance planning. Performance evaluation criteria can be specified by the response time between units and the utilization of each unit. One has to also consider the ease and the cost of installation, maintenance, repair. Based on these characteristics, different system configuration can be evaluated and compared through results about evaluation criteria in order lo select the best DCS for particular process. The results, in abbreviated form, of the simulation DCS controlling a CAL(Continuos Annealing Line) plant of iron process ate presented.

• Nuclear Engineering and Technology
• /
• 제30권5호
• /
• pp.444-451
• /
• 1998

The cost-effective reduction of occupational radiation exposure (ORE) dose at a nuclear power plant could not be achieved without going through an extensive analysis of accumulated ORE dose data of existing plants. It is necessary to identify what are high ORE jobs for ALARA implementation. In this study, the Rank Sum Method (RSM) is used in identifying high ORE jobs. As a case study, the database of ORE-related maintenance and repair jobs for Kori Units 3 and 4 is used for assessment, and top twenty high ORE jobs are identified. The results are also verified and validated using the Friedman test, and RSM is found to be a very efficient way of analyzing the data.

• 한국기계가공학회지
• /
• 제21권9호
• /
• pp.105-109
• /
• 2022

In this study, the cause of the acceleration failure of Hyundai Motor's 2.0-liter CRDi engine was analyzed. We tried to find problems through MDA (Measuring Data Analyzer) based on data such as vehicle speed, air intake, and air-fuel ratio obtained during the actual driving process. As a result, it was analyzed that the failure of the EGR valve exceeded the NOx emission standard and caused a decrease in engine output. Through this study, it is possible to reduce the time and cost of unnecessary maintenance and repair, and it is expected that a rapid cause analysis will be possible in the case of new failure diagnosis in the future.

• 한국해안·해양공학회논문집
• /
• 제29권2호
• /
• pp.109-120
• /
• 2017

경사제 피복재를 예방적으로 유지관리할 수 있는 조건기반 할인비용모형을 제안하였다. 하중발생 사상을 이산시간 확률과정으로 고려하는 추계학적 누적 피해모형과 보수보강 비용에 대한 경제성 모형을 결합하여 수학적으로 유도하였다. 특히 본 논문에서 유도된 조건기반 유지관리의 할인비용모형은 시간에 따른 비용의 가치 뿐만 아니라 누적피해의 비선형성도 고려할 수 있다. 본 연구의 결과는 기존 모형들의 결과와 비교하여 만족스럽게 검증되었다. 또한 구조물의 중요도와 이자율 변화에 대한 민감도 분석도 수행하여, 구조물의 중요도가 높아질수록 예방적 보수보강의 최적시기는 빨라지나 이자율은 커질수록 반대의 경향이 나타난다는 것을 알았다. 한편 본 연구에서 유도된 추계학적 기대비용모형을 이용하여 여러 조건에 대하여 임의의 경사제 피복재 단면을 해석하였다. 표본경로기법을 적용하여 임의의 태풍 내습에 따른 경사제 피복재의 기대 누적피해수준을 예측하여 피해강도함수의 계수들을 추정할 수 있었다. 특히 하중발생 과정을 HPP(Homogeneous Poisson Process) 뿐만 아니라 DSPP(Doubly Stochastic Poisson Process)로도 해석하여 기대 누적피해수준에 미치는 하중발생의 불확실성에 대한 영향을 분석하여 하중발생사상을 이산시간 확률과정으로 고려해도 된다는 것을 확인하였다. 조건기반 할인비용모형의 해석 결과에 의하면 경사제 피복재의 설계조건에 따라 기대 누적피해수준의 거동특성이 크게 달라지고 이에 따라 예방적 보수보강을 수행하는 최적시기도 변한다는 것을 알 수 있었다. 마지막으로 파괴한계, 구조물의 중요도 그리고 이자율을 변화시키면서 예방적 유지관리를 가장 경제적으로 수행할 수 있는 최적시점과 피해규모를 결정할 수 있었다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 춘계학술대회 논문집
• /
• pp.1446-1448
• /
• 2004

Communication line used in the rail-road have different use from subscriber line in the public telecommunication. But, when an existing communication equipment is replaced, by applying new high-speed transfer technology, we can anticipate the increase of transmission rate and decrease of waiting time according to high-speed of communication line. cost reduction of infrastructure construction and maintenance/repair according to centralization of communication line and transmission equipment. In this study, the transmission scheme of several xDSL(Digital Subscriber Line) modems were compared and analyzed. The way of applying xDSL modem to the metal cable which is used in the JR(Japan Railroad) is analyzed. In addition, the result tested in railroad communication line was reviewed.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2001년도 춘계학술대회 논문집
• /
• pp.381-386
• /
• 2001

In many countries the slab track of railroads is mostly applied on the railroad bridges and tunnels, however it hasn't been constructed in the tunnel in Korea. Presently the Korea high speed railway construction authority is planning to construct slab track in the tunnels to minimize the cost of maintenance and repair. In this study, dynamic characteristics of the railroad roadbed which was constructed using crushed stones obtained from tunnel construction was investigated through the field investigation, real scale model test and numerical analysis. As a conclusion, the roadbeds built with the crushed stones produced at the tunneling site satisfy the requirement of roadbed in terms of displacement and earth pressure for the slab track in tile tunnel.

• 한국국방경영분석학회지
• /
• 제27권1호
• /
• pp.58-72
• /
• 2001

This research deals with the weapon system RAM which is the reliability, availability and maintainability for weapon systems. This weapon system RAM is one of very important factors because it is related to the life cycle cost and combat readiness of weapon systems. Therefore, in this research we introduce the weapon system RAM and analyze the problems of weapon system RAM management during system life cycle including acquisition period. Finally we suggest an alternative to improve the weapon system RAM in various agencies which are the department of defense and army headquarter level, etc., in the process of defense acquisition.