• Proceedings of the KSR Conference
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• 2008.06a
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• pp.733-741
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• 2008

An important problem in reliability analysis for repairable systems is to model the maintenance effect. The most of researches have assumed two extreme cases; one is perfect maintenance and the other is minimal maintenance. However, there are many cases in real situations that the maintenance effect are between both of two extreme cases. This article deals with the problem determining the imperfect preventive maintenance intervals for the doors in Metro EMU

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.616-623
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• 2002

This paper proposes a new DFA methodology that ran estimate the standard assembly time and evaluate the assemblability of parts for small-sized product. We deride some determining and influencing factors related with assembly process and measure the assembly time using notion analysis to estimate of assemblability. We deduce quantitative store of assemblability through analysis of a correlation between determining factors and grade of influencing factors.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.1
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• pp.22-30
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• 2005

The purpose of this study is to present a method to determine the optimal stop time of HVAC using the Artificial Neural Network model, which is one of the learning methods. For this, the performance of determining the stop time of HVAC for unexperienced learning data was evaluated, and time interval for measurement of input data and permissible error needed for practical application of ANN model were presented using the results from daily simulation.

• Proceedings of the KIEE Conference
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• summer
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• pp.33-35
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• 2004

The secondary voltage control is the method the pilot bus controls the voltage of the voltage control area sufficiently uncoupled form its neighbours within a area to k slightly influenced by the actions carried out in the other areas. This paper presents the comparison of three methods which determines the voltage control area for the secondary voltage control in power system. Additionally, this paper selects the fitted thing of three methods determining the voltage control area, VSSA, and using it applies the procedure determining the voltage control area to KEPCO system.

• Journal of Environmental Science International
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• v.8 no.2
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• pp.189-195
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• 1999

Determining factors and temporal & spatial characteristics of COD(Chemical Oxygen Demand) at the sea surface in Jinhae bay have been examined by using seasonal data, taken at twenty six stations over the whole bay during 1989~1994 by NERDA. The data have been analyzed in terms of long term means, anomalously large values. Jinhae bay is divided into three regions based on the time mean : mouth of Jinhae bay, inner sea of Masan bay, western sea of Jinhae bay called region 1,2 and 3, respectively. The horizontal distribution of the long term mean of COD at each station is similar to those of nitrogen and phosphorus. Characteristics of whole mean variation in the year shows high range of variation in region 2. It was appear to decreases every year in whole trend. Factors determining seasonal variation in whole COD mean are relative to salinity and nutrient, affected by precipitation in summer. Spatial variation shows high range of fluctuation in region 2 compare to other region. Factors determining of spatial variation of COD was appear to nutrient, affected by pollutant load of land area and bottom sediment. The long term mean of COD at each station is closely related with thats of nutrients. The correlation coefficient between COD and nitrogen, phosphate phosphorus was found to be high as 0.75, 0.78, respectively. Anomalously large COD was observed 14 times at 6 stations. These stations are located in inner sea of Masan bay(Region 2) and Songjeong bay(Region 1). The seasonal frequency of the observed anomalous COD is large in April, and other seasons are much the same.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.4
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• pp.145-152
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• 2019

All machines deteriorate in performance over time. The phenomenon that causes such performance degradation is called deterioration. Due to the deterioration, the process mean of the machine shifts, process variance increases due to the expansion of separate interval, and the failure rate of the machine increases. The maintenance model is a matter of determining the timing of preventive maintenance that minimizes the total cost per wear between the relation to the increasing production cost and the decreasing maintenance cost. The essential requirement of this model is that the preventive maintenance cost is less than the failure maintenance cost. In the process mean shift model, determining the resetting timing due to increasing production costs is the same as the maintenance model. In determining the timing of machine adjustments, there are two differences between the models. First, the process mean shift model excludes failure from the model. This model is limited to the period during the operation of the machine. Second, in the maintenance model, the production cost is set as a general function of the operating time. But in the process mean shift model, the production cost is set as a probability functions associated with the product. In the production system, the maintenance cost of the equipment and the production cost due to the non-confirming items and the quality loss cost are always occurring simultaneously. So it is reasonable that the failure and process mean shift should be dealt with at the same time in determining the maintenance time. This study proposes a model that integrates both of them. In order to reflect the actual production system more accurately, this integrated model includes the items of process variance function and the loss function according to wear level.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.443-450
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• 2009

In this paper, we propose optimizing a remarshaling plan in an automated stacking yard using a cooperative coevolutionary algorithm (CCEA). Remarshaling is the preparation task of rearranging the containers in such a way that the delay are minimized at the time of loading. A plan for remarshaling can be obtained by the following steps: first determining the target slots to which the individual containers are to be moved and then determining the order of movement of those containers. Where a given problem can be decomposed into some subproblems, CCEA efficiently searches subproblems for a solution. In our CCEA, the remarshaling problem is decomposed into two subproblems: one is the subproblem of determining the target slots and the other is that of determining the movement priority. Simulation experiments show that our CCEA derives a plan which is better in the efficiency of both loading and remarshaling compared to other methods which are not based on the idea of problem decomposition.

• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.355-362
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• 2001

This study was conducted to propose the way to develop and strengthen competitiveness of the Korean paper industry by analysing current competitiveness and the factors which determine and influence it. Delphi method was employed to identify determining factors of international competitiveness of Korean paper industry and evaluate the level of competitiveness. The competitiveness both in the domestic and foreign markets was evaluated by analysing each product market faced by the Korean paper industry in light of each of the determining factors. Based on the Delphi survey results, in order of importance, product quality, manufacturing cost, transportation and storage, timely delivery, supply of raw materials, and marketing were identified as the factors determining international competitiveness. Among them, it was revealed that Korean paper industry has a certain level of competitiveness in the factors such as product quality and timely delivery service while supply of raw materials and manufacturing costs were found to be inferior to overseas manufacturers in both domestic and foreign markets.

• Journal of Preventive Medicine and Public Health
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• v.38 no.1
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• pp.16-24
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• 2005

Objectives : To help develop strategies to cope with the changes arising from the rapid aging process by predicting the determining factors of intention to actual use of the charged long-term care services for elderly as perceived by the middle aged who play the major role of supports. Methods : Subjects were the parents (men 177, women 507) in their 40s of the students selected from a university of Busan city. A questionnaire survey was conducted for 4 weeks in October 2003 about the knowledge for long-term care service, the intention of actual use, and the preferences about the type of service suppliers. Data analysis was performed with frequency, chi-square test, and t-test using SPSS program (ver 10.0K), along with data mining using decision tree of Enterprise Miner V8.2 by SAS. Results : About half of the subjects (53.7%) had the actual experiences of elderly supports. Intentions to use the charged services were relatively high in home visiting nursing care service (40.1%) and long-term care facilities service (40.4%), and were influenced by previous knowledge about the services. The intentions were stronger in women, those with higher education, and those with greater income levels. Actual elderly supports were mostly (80%) done by women, and the perceived burdens for the supports were bigger in women and those of lower socioeconomic level. Desired charges were about 10,000 won for the bath service, 20,000 won for the rests services per day, and about 500,000 won for the long-term care facilities service per month. From the result of decision tree analysis, the job professionalism was the most important determining factor of intention to actual use of the services with validation as $63{\sim}71%$. Health and welfare mixed type facilities were preferred, and the most important consideration was the level of professionalism. Conclusions : Intention to actual use of the charged services was largely determined by the aspects of time and cost. Polices to increase the number of service suppliers and to decrease the burdens perceived by actual supporters were strongly recommended.

• The Korean Journal of Pain
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• v.25 no.2
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• pp.81-88
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• 2012

Background: In discography performed during percutaneous endoscopic lumbar discectomy (PELD) via the posterolateral approach, it is difficult to create a fluoroscopic tunnel view because a long needle is required for discography and the guide-wire used for consecutive PELD interrupts rotation of fluoroscope. A stereotactic system was designed to facilitate the determination of the needle entry point, and the feasibility of this system was evaluated during interventional spine procedures. Methods: A newly designed stereotactic guidance system underwent a field test application for PELD. Sixty patients who underwent single-level PELD at L4-L5 were randomly divided into conventional or stereotactic groups. PELD was performed via the posterolateral approach using the entry point on the skin determined by premeasured distance from the midline and angles according to preoperative magnetic resonance imaging (MRI) findings. Needle entry accuracy provided by the two groups was determined by comparing the distance and angle measured by postoperative computed tomography with those measured by preoperative MRI. The duration and radiation exposure for determining the entry point were measured in the groups. Results: The new stereotactic guidance system and the conventional method provided similarly accurate entry points for discography and consecutive PELD. However, the new stereotactic guidance system lowered the duration and radiation exposure for determining the entry point. Conclusions: The new stereotactic guidance system under fluoroscopy provided a reliable needle entry point for discography and consecutive PELD. Furthermore, it reduced the duration and radiation exposure associated with determining needle entry.