• Journal of Korean Institute of Industrial Engineers
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• v.27 no.4
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• pp.366-373
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• 2001

Economic component screening procedures for multi-component assembly products supplied with warranty are proposed. It is assumed that the screening variable is continuous and the performance variable is dichotomous. Logistic and normal models are considered; the proportion of conforming items is a logistic function of the screening variable in the logistic model and the screening variable given the performance variable is normally distributed in the normal model. Cost models are constructed which involve three cost components; screening inspection cost for each component, cost due to disposing a rejected component, and warranty cost for an assembly product. Methods of finding the optimal screening procedures are presented and numerical examples are given.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.274-277
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• 2006

Nanostructured carbon (nm-C), including carbon nanotubes and nanofibers (CNTs/CNFs) is promising for low-cost field emission display (FED) application. By modification of CNTs/CNFs, uniform CNTs/CNFs can be obtained and used for field emission cathode (FEC) on glass substrate. By screen-printing (SP) and electrophoretic deposition (EPD) process, large area FEC can be obtained. The FED properties are studied and compared. Both SP and EPD FEC show excellent field emission properties, such as low emission field and uniform emission, after optimization the fabrication process. While EPD FEC exhibits better luminescence image. By vacuum sealing, the low cost nm-C-FED prototypes based on EPD cathode have been demonstrated.

• Korea Journal of Hospital Management
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• v.9 no.2
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• pp.102-127
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• 2004

The objective of this study is to analyze a current trend of and relating factors on profitability of the Korean Public Corporation Medical Centers(KPCMCs, hereinafter, hospitals) in Korea. There are 34 hospitals in Korea as of 2004. Among these hospitals some are red ink hospitals, others are black inks in terms of profitability. Data were collected by Korea Health Industry Development Institute(KHIDI) Statistics for Hospital Management 2000-2002 and Ministry of Health and Welfare(MOHW) financial data of public hospitals which was planned to coordinate public health care services roadmap in the long run. The samples are 32 hospitals. Profitability was measured in the aspect of profit rate with normal profit to total assets, and normal profit to gross revenues as dependent variables in respective. Independent variables were classified by general factors, i.e., location, intern/resident training, period of opening, number of beds, and managerial factors(current ratio, fixed ratio, liability to total assets, total assets turnover, personnel costs, materials cost, administrative cost), and finally factors related to patient treatment(average length of stay, bed occupancy rate, admission ratio of outpatients). The methods of analysis are correlation and multiple regression analysis. This study shows firstly, a lot of hospitals are optimal current ratio. Hospitals in upper 100% current ratio are 81.2%. And the personnel cost in total costs are high. Secondly, the trend of normal profit to gross revenues of hospitals are deteriorating gradually. And lastly, as a result of multiple regression analysis, the factors had on significant effect on normal profit to total assets are fixed ratio(+), liability to total assets(-), bed occupancy rate(+), admissions of outpatients(+), etc. And the factors had on significant effect on normal profit to gross revenues are current ration(+), fixed ratio(+), personnel cost(-), administrative expenses(-), admissions of outpatients(+), etc. In conclusion, to improve the profitability of hospitals, the efforts to reduce personnel cost and average length of stay might be needed. And also beds utilization rate need to be increased.

• KIEE International Transactions on Power Engineering
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• v.12A no.1
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• pp.31-35
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• 2002

This paper presents a new operation scheme of UPFC to minimize both generation costs and active power losses in a normal operation state of power system. In a normal operation, cost minimization is a matter of primary concern among operating objectives. This paper considers two kinds of costs, generation costs and transmission losses. The total generation cost of active powers can be minimized by optimal power flow, and active power losses in the transmission system can be also minimized by power flow control of UPFC incorporated with minimization of generation costs. In order to determine amounts of active power reference of each UPFC required for the cost minimization, an iterative optimization algorithm based on the power flow calculation using the decoupled UPFC model is proposed. For verification of the proposed method, intensive studies have been performed on a 3-unit 6-bus system equipped with a UPFC.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.153-159
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• 2018

Many researches have been carried out on carbonation, a representative deterioration in underground structure. The carbonation of RC (Reinforced Concrete) structure can cause steel corrosion through pH drop in concrete pore water. However extension of service life in RC structures can be obtained through simple surface protection. Unlike the conventional deterministic maintenance technique, probabilistic technique can consider a variation of service life but it deals with only normal distributions. In the work, life time-probability distributions considering not only normal but also log distributions are induced, and repair cost estimation technique is proposed based on the induced model. The proposed technique can evaluate the repair cost through probabilistic manner regardless of normal or log distribution from initial service life and extended service life with repair. When the extended service life through repair has log distribution, repair cost is effectively reduced. The more reasonable maintenance strategy can be set up though actual determination of life-probability distribution based on long term tests and field investigations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.10-19
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• 2019

Management plan with repairing is essential for RC structures exposed to chloride attack since durability problems occur with extended service life. Conventionally deterministic method is adopted for evaluation of service life and repair cost, however more reasonable repair cost can be obtained through continuous repair cost from probabilistic maintenance technique. Unlike the previous researches considering only normal distribution of life time, PLTFs (Probabilistic Life Time Function) which can be capable of handling log and normal distributions are attempted for initial and repair service life, and repair cost is evaluated for OPC and GGBFS concrete. PLTF with log distributions in initial service life is more effective to save repair cost since it is more dominant after average than normal distribution. Repair cost in GGBFS concrete decreases to 30% of OPC concrete due to longer initial service life and lower repairing event. The proposed PLTF from the work can handle not only normal distributions but also log distributions for initial and repair service life, so that it can provide more reasonable repair cost evaluation.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.1
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• pp.113-120
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• 2013

This study aimed to obtain quantitative data for WWTP operators in phosphorus removal process. This was done by reviewing and comparing phosphorus removal efficiency(%), coagulants dosage(Al/P and $Al_2O_3$(mg/L)), sludge production($kg/m^3$), and operation cost($won/m^3$) of start-up and normal operation data. Phosphorus removal efficiency of all tertiary treatment process was up to 70 ~ 89 % in start-up and normal operation. Average molar ratio(Al/P) was similar as 5 in both operations, but average coagulants dosage (mg/L) of start-up (8.5 mg/L) was higher than normal operation (6.2 mg/L). Average operation cost was higher for start-up ($33.6won/m^3$) than normal operation ($28.4won/m^3$), while electricity cost required for the normal operation ($9.0won/m^3$) was higher by $3.5won/m^3$.

• Journal of Preventive Medicine and Public Health
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• v.14 no.1
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• pp.3-12
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• 1981

To identify the changes in professional care patterns after the introduction of medical insurance in Korea, professional care in hospitals and clinics of two succeeding years were compared. The hospitals and clinics selected for this study were those which located in Seoul city. Hospitals were classified into 3 categories: university hospital, general hospital and hospital. The diseases selected for this study were acute appendicitis and normal delivery. They were selected because their disease courses are considered to be fairly stable. The variables used for this study were length of stay, total hospital costs, costs of each components of cares. The information used for this study was obtained from the official forms requested by the medical facilities to the Korea Medical Insurance Corporation. The two periods studied were 3 months of each year from March 1st to May 31st in 1979 and 1980, The total number of normal delivery studied was 289 in 1979, 301 in 1980 respectively and the acute appendicitis was 92 and 111 respectively. In order to compare the quantity of medical care between 2 study periods the insurance price scores of 1979 were converted to prices of 1980. For statistical test of difference between 2 periods T-test and Welch's test were used. The result of the study were briefly summarized in below. 1. No significant difference was observed in the average length of stay of both disease between two study periods in all types of hospitals. 2. No significant difference was observed in the average total hospital costs of both diseases in all types of hospital, but in the private clinic the average clinic costs was rather decreased significantly in 1980. 3. More cost decrease were seen than cost increase in 1980 in all types of facilities, More cost changes by items were seen in acute appendicitis than in normal delivery between two study periods. The total hospital costs can be devided into 2 portions: charges for drug and material and for physician. In normal delivery, costs for physician's charges was significantly decreased in almost all the hospitals and costs for drug and material were not changed significantly in all the hospitals in 1980. In the university hospitals, however, the costs for drug and material were increased significantly in 1980. The cost decrease for physician's charge were mainly due to the decrease in the costs of laboratory test, treatment and physical therapy. The increase in the costs for the drug and material in the university hospitals was mainly due to the increase in the cost for drugs for oral administration and injection. 4. The proportion of components of medical care in the hospital has not been changed significantly, however, the cost for injection in normal delivery was characteristically increased in 1980 in all hospitals studied. In general the proportion of the costs for drug and material was tended to increase and the costs for physician was tended to decrease in 1980. The increase in the costs for drug and material were considered to be due to increase in the cost for drugs for oral administration and injection. The decrease in the costs for physician were due to decrease in the costs of laboratory test, treatment and physical therapy. Above mentioned changes in hospital and clinic care patterns are considered to be mostly influenced by the review criteria set by the K.I.C. for the assessment of the fee request made by clinics and hospitals.

• Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.88-95
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• 2014

Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.3
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• pp.240-246
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• 2002

In this paper, economic screening procedures with dichotomous performance variable T and continuous screening variable X are considered when the rejected items are reprocessed. Two models are considered; normal and logistic models. It is assumed that X given T is normally distributed in the normal model, and P(T=1|X=x) is given by a logistic function in the logistic model. Profit models are constructed which involve four price/cost components; selling price, cost from an accepted nonconforming item, and reprocessing and inspection costs. Methods of finding the optimal screening procedures are presented and numerical examples are given.