• 대한전기학회논문지
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• 제40권8호
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• pp.731-740
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• 1991

This paper presents a knowledge based system to solve reactive power/voltage control problem in a power system. The methods to reduce inference time are proposed in inferring the solution of problem in the knowledge base which consists of heuristic rules and inowledge of experts. A set of indices drawn from the heuristic knowledge on the power system is utilized to make up for the defect of existing knowledge based systems which determine both the location and the amount of reactive power compensation devices. The concept of set of indices developed in this paper makes it possible to infer the amount of reactive power source only since the bus order list representing priority for the location of reactive power compensator to be switched on can be determined in advance. From the fact that there exists a relationship between the system voltage pattern and the reactive power pattern in operation, the pattern recognition technique is introduced to reduce the inference time in solving the severe voltage problem. To demonstrate the usefulness of the proposed knowledge based system, the IEEE 30 bus system is chosen as a sample system. The results of case study are also presented.

• 한국경영과학회지
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• 제26권1호
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• pp.71-85
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• 2001

This paper considers a cost model for a U-shaped manufacturing cell formation which incorporates a required number of machines and various material flows together under multi-part multi-cell environment. The model is required to satisfy both the specified operation sequence of each part and the total part demand volume, which are considered to derive material handling cost in U-shaped flow line cells. In the model several cost-incurring factors including set-up for batch change-over, processing time for operations of each part, and machine failures are also considered in association with processing load and capacity of each cell. Moreover, a heuristic for a good machine layout in each cell is newly proposed based on the material handling cost of each alternative sequence layout. These all are put together to present an efficient heuristic for the U-shaped independent-cell formation problem, numerical problems are solved to illustrate the algorithm.

• 대한안전경영과학회지
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• 제19권3호
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• pp.89-95
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• 2017

This paper presents another maintenance policy for a group of units under finite operating horizon. A group of identical units are subject to random failures. Group maintenances are performed to all units together at specified intervals, and the failed units during operation are remained idle until the next group maintenance set-up. Unlike the traditional assumption of infinite operating horizon, we adopt the assumption of the finite operating horizon which reflect the rapid industrial advance and short life cycle of modern times. The units are under operation until the end of the operating horizon. Further, the operation of units are extended to the first group maintenance time after the end of the horizon. The total cost under the proposed maintenance policy is derived. The optimal group maintenance interval and the expected number of group maintenances during the horizon are found. It is shown that the proposed policy is better than the classical group maintenance policy in terms of total cost over the operating horizon. Numerical examples are presented for illustrations.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.400-405
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• 2005

The vertical slope of railway track is the differences of attitude for the horizontal distances between two positions of railway. It is better to be small vertical slope for the comfortable of passengers and the operation of railway system. However, the variable vertical slope is required that the simple vertical slope causes the huge quantities of embankment and cutting, the continuous welded rail tunnels, the continuous welded rail bridges, etc,. This research is for the relation between the vertical slopes and the trainset performances. This research shows that the effective vertical slopes for the operation of railway. The velocity of car and operation time and the consumed energy was considered for each vertical slope and type of car power system. The result of suitable vertical slope from this research is to be used for the design of railway plan.

• 수산해양기술연구
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• 제58권3호
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• pp.214-222
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• 2022

This study calculated the on-site measurement (Tier 4) of greenhouse gases emitted during the production stage of major fishing periods that utilize set nets and bamboo weir fishing boats. In addition, using theoretically calculated results (Tier 1), the emission factor presented by the Intergovernmental Panel on Climate Change (IPCC) was comparatively analyzed. On average, carbon emissions for each operating period in the bamboo weir and set net were calculated to be 0.16 and 3.58 kg CO₂ time^-1, respectively; and the measurement values (Tier 4) for each tool were about 4-17 times lower than their respective theoretical values (Tier 1). Significant differences were found based on engine performance. As port entry, port departure, and operating periods of the vessels show negligible variation with short distances, the operation of the vessel engine was considered as the main variable for carbon emissions in anchovy set net fishing.

• 한국컴퓨터정보학회논문지
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• 제20권11호
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• pp.69-75
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• 2015

This paper suggests heuristic polynomial time algorithm for crew scheduling problem that is a kind of optimization problems. This problem has been solved by linear programming, set cover problem, set partition problem, column generation, etc. But the optimal solution has not been obtained by these methods. This paper sorts transit costs $c_{ij}$ to ascending order, and the task i and j crew paths are merged in case of the sum of operation time ${\Sigma}o$ is less than day working time T. As a result, we can be obtain the minimum number of crews $_{min}K$ and minimum transit cost $z=_{min}c_{ij}$. For the transit cost of specific number of crews $K(K>_{min}K)$, we delete the maximum $c_{ij}$ as much as the number of $K-_{min}K$, and to partition a crew path. For the 5 benchmark data, this algorithm can be gets less transit cost than state-of-the-art algorithms, and gets the minimum number of crews.

• 대한간호학회지
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• 제28권1호
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• pp.117-131
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• 1998

The purpose of this study was to develop a critical pathway for case management for patients who have received Coronary Artery Bypass Graft (CABG) because of Ischemic Heart Disease(IHD) which is a factor of rising medical expenses. For this study. a conceptual framework was developed through a review of the literature including six critical pathways which are currently being used in USA. In order to identify the overall service contents required by these patients and to draw up a preliminary critical pathway, 30 cases of medical records of patients who had CABG because of IHD between January, 1995 to June. 1996 at the Cardiovascular Center of Yonsei Medical Center in Seoul were analyzed. An expert validity test was done for the preliminary critical pathway and clinical validity test was also done using seven IHD patients with CABG between November 11 and 23, 1996. After these processes. the final critical pathway was developed. The results of this study are summarized as follows : 1. The vertical axis of the critical pathway includes the following eight items : tests, nutrition, medications, consultations, activity, assessments, treatments, education discharge planning and the horizontal axis includes the time from the start of hospitalization to discharge. 2. Analysis of the 30 medical records indicated that the average length of stay was 20.2days with the average length of stay from hospitalization day to operation day being 6.2 days, and the average length of stay from operation day to discharge day was 13. 9 days. Analysis of the service contents showed that the horizontal axis of the preliminary critical pathway was set from hospitalization to the 14th post operation day and the vertical axis was set to include eight items, the contents which ought to have occurred, according to the time frames of the horizontal axis. 3. As a result of the experts validity, it was found that among the total of 571 items. there was over 83% agreement for 482 items, less than 83% for 89 items, which were then deleted and a revision of the critical pathway was done. 4. A clinical validity test was done using seven IHD patients with CABG. During the process, three patients were deleted because they were out of the criteria the investigator set. Finally, four patients were used. The result of study indicated that only one patient was discharged on the tenth post operation day, which was one day later than the expected day. Three patients were discharged later than the expected day from three days to nine days. All the cases progressed on schedule until the operation day and the first post operation day, but from the second post operation days, there were differences between the critical pathway and the actual practice. The differences came from tests, assessments, and treatments. 5. On the basis of the results of the clinical validity test. the following revisions in the final critical pathway were made : the transfer from ICU to step down ward would be the second post operation day, and the transfer to a general ward, the fifth post operation day, for patients who complained of lack of sleep from the fifth post operation day to discharge, a sleeping pill would be prescribed, skin observations would be performed routinely from immediately after the operation until the third post operation day, and would continue if there was a sign of skin injury on the fourth post operation day, and assessment of chest pain would be done from the third post operation day, and the “stairs climbing” item, expected to be done on the ninth post operation day would be deleted. In conclusion, this critical pathway is partially applicable to the care of patients with CABG but there are some parts needed to be further investigated.

• 대한토목학회논문집
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• 제30권3D호
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• pp.241-246
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• 2010

본 연구는 버스정보시스템(BIS)의 운영을 통해 수집되고 있는 데이터를 이용하여 도시내 가로의 통행시간을 추정하기 위한 연구이다. 기존의 버스시스템에 첨단정보통신 기술을 접목한 BIS는 많은 지방자치단체에서 구축하여 운영 중에 있다. 그러나 이러한 기술동향을 반영한 연구는 부족한 실정이다. 기존에 구축된 BIS의 운영을 통해 유용한 교통정보들이 수집되고 있으나 수집된 데이터의 활용은 활발히 이루어지지 못하고 있다. 본 연구에서는 BIS의 운영을 통해 수집되고 있는 버스운행 데이터를 이용하여 도시내 가로의 링크통행시간 추정을 통해 도시의 교통관리에 활용하고 운전자에게 교통정보를 제공하기 위한 기초적인 연구를 수행하고자 하였다. 연구결과 버스의 링크통행시간이 두 개의 군집으로 나타났으며 따라서 링크통행시간을 두 개의 군집으로 나누어 추정모형을 구축하였다. 구축된 모형을 통계적으로 검정하기 위해 T-test를 실시한 결과 통계적으로 유의한 것으로 분석되었다.

• 수산해양기술연구
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• 제58권4호
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• pp.317-325
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• 2022

Korean tuna purse seine fishery in the Western and Central Pacific Ocean (WCPO) began to operate in earnest in the early 1980s. Since then, the total catch has shown an increasing trend and the target species are skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacare) and bigeye tuna (Thunnus obesus). Based on the operational data of Korean tuna purse seine fishery from 2016 to 2020, the catch rates of target species (skipjack and yellowfin tunas) were analyzed by operation time for set types (free school and FAD sets). In the case of the free school sets, they were usually made from sunrise to sunset, and the catch rate was high before and after sunrise for skipjack tuna and before sunset for yellowfin tuna. On the other hand, for the FAD sets, more than 90% of them were made just before sunrise, and there were few operations during the daytime. The purpose of this study is to examine whether there are differences in the catch rate of skipjack and yellowfin tunas by operation time and by school type for Korean tuna purse seine fishery in the WCPO, which could be helpful in understanding its fishing characteristics and providing useful information for developing the stock indices of the target species.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.313-314
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• 2006

Indicating product quantity by real time can be benefit both worker and management. Worker can compare real product quantity with its target and can adjust working speed to match with goal. Therefore, so called JPH equipment developed to indicate target quantity of product. As a main processor PIC16F877 was used and FND display were used to indicate current time, elapsed time, JPH value and target amount of product. Values like JPH and starting time, etc. are can easily be set by $4{\times}4$ numeric keypad and display datum likes target amount of product, current time and elapsed time, etc are displayed on FND by RS232 serial transmit. The operation of JPH equipment are tested and verified through long term test and are proved acting properly on working conditions.