• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.422-428
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• 2013

In many cases, an $\bar{X}$ control chart which is based on the performance variable is used in industrial fields. However, if the performance variable is too costly or impossible to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled using surrogate variables. In this paper, we propose a model for the economic design of a VSI (Variable Sampling Interval) $\bar{X}$ control chart using a surrogate variable that is linearly correlated with the performance variable. The total average profit model is constructed, which involves the profit per cycle time, the cost of sampling and testing, the cost of detecting and eliminating an assignable cause, and the cost associated with production during out-of-control state. The VSI $\bar{X}$ control charts using surrogate variables are expected to be superior to the Shewhart FSI (Fixed Sampling Interval) $\bar{X}$ control charts using surrogate variables with respect to the expected profit per unit cycle time from economic viewpoint.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.838-843
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• 2008

Cause of struggling to escape from dependency of fossil fuels, the fuel cell and the Plug-in Hybrid Electric Vehicle (PHEV) draw attention in the all of the world. Especially, the Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems have been anticipated for next generation's energy supplying system, and we can predict the PHEV will enlarge the market share in the next few years to reduce not only the air pollution in the metropolis but the fuel-expenses of commuters. This paper presents simulation results about the strategy of smart charging system for PHEV in the residential house which has 1 kW PEMFC cogeneration system. The smart charging system has a function of recommending the best time to charge the battery of PHEV by the lowest energy cost. The simulated energy cost for charging the battery based on the electricity demand data pattern in the house. The house which floor area is $132\;m^2$ (40 pyeong.). In these conditions, the annual gasoline, electricity, and total energy cost to fuel the PHEV versus Conventional Vehicle (CV) have been simulated in terms of cars' average life span in Korea.

• Journal of Korean Society of Forest Science
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• v.96 no.4
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• pp.393-400
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• 2007

This research was conducted to develop the demand function and to estimate an increase of national parks visitors considering abolition of entrance fee, using dichotomous choice contingent valuation. Also, this study estimated the additional management cost with an increase of visitors. As a result, an average increase rate was estimated about 5.8% considering abolition of entrance fee. Each increase rate of national park is analyzed Bukhansan 9.0%, Gyeryongsan 8.5%, Deogyusan 8.2%, respectively. Seoraksan is the lowest rate of increase, 3.0%. Total additional management cost of 18 national parks was estimated about 5.6 billion won, Bukhansan 1.4 billion won, Jirisan 0.7 billion won, Dadohaehaesang 0.5 billion won, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.153-162
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• 1997

M/G/1 queueing system is one of the most widely used one to model the real system. When operating a real systems, since it often takes cost, some control policies that change the operation scheme are adopted. In particular, the N-policy is the most popular among many control policies. Almost all researches on queueing system are based on the assumption that the arrival rates of customers into the queueing system is constant, In this paper, we consider the M/G/1 queueing system whose arrival rate varies according to the servers status : idle, set-up and busy states. For this study, we construct the steady state equations of queue lengths by means of the supplementary variable method, and derive the PGF(probability generating function) of them. The L-S-T(Laplace Stieltjes transform) of waiting time and average waiting time are also presented. We also develop an algorithm to find the optimal N-value from which the server starts his set-up. An analysis on the performance measures to minimize total operation cost of queueing system is included. We finally investigate the behavior of system operation cost as the optimal N and arrival rate change by a numerical study.

• Journal of Korean Medicine Rehabilitation
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• v.23 no.3
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• pp.159-175
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• 2013

Objectives Herniated Intervertebral Disc of C-spine is one of the most common diseases that causes posterior neck pain. This study was designed to analyze the general distribution and hospital cost by day and case of Korean medical treatment for Cervical Herniated Intervertebral Disc (HIVD). Methods The 132 impatients for treatment of HIVD were analyzed according to the distribution of sex, age, the duration of HIVD, the contributory factors, the Clinical grade at admission, the clinical findings at admission, the duration of hospitalization, the clinical grade at admission and the hospital cost per day and case. Results 1) The total hospital cost per case averaged 1,985,600 Won, which was consisted of room charge 584,044 Won (29.41%), performance fee 511,463 Won (25.76%), herbal medication 381,517 Won (19.21%), Korean medical physiotherapy 296,310 Won (14.92%), food expenses 199,997 Won (10.07%) in order. 2) The total hospital cost per day averaged 137,285 Won, which was consisted of room charge 39,036 Won (28.43%), performance fee 33,594 Won (24.47%), herbal medication 30,642 Won (22.32%), food expenses 12,870 Won (9.37%), and the average duration of hospitalization was 15.1 days. 3) There was statistically significant difference in the consultation fee, room charge, and herbal medication on the part of sex. 4) There was statistically significant difference not only in the performance and consultation on the part of duration of hospitalization but also the in the duration of average duration of hospitalization. 5) There was statistically significant difference in the Korean medical physiotherapy and herbal medication on the part of clinical findings. 6) There was statistically significant difference in the Korean medical physiotherapy and herbal medication on the part of duration of HIVD. 7) There was statistically significant difference in the Korean medical physiotherapy and herbal medication on the part of clinical outcome. 8) There was not only statistically significant difference in the performance, but also in the herbal medication on the part of clinical grade at admission. Conclusions This study provides plenty of information to design out the specific terms of Korean medical expenses of Cervical HIVD inpatients hospitalized at Korean medicine hospital.

• Journal of Korean Society for Quality Management
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• v.13 no.1
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• pp.56-64
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• 1985

This paper presents a general algorithm of multi-item continuous review models to obtain simultaneous solutions for ordering quantities and reorder points for each item in an inventory, while satisfying constraints on average inventory investment and reordering workload. Two models are formulated'in each model the heuristic method is utilized, and the partial back-logging is considered. In the first model, the objective function is the minimization of total inventory variable cost. In the second model, the objective function is the minimization of total time-weighted shortages, and the ordering, holding, and stockout costs in this model are independent each other. A numerical example is also solved to present application of each model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.1
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• pp.124-130
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• 2015

In many inventory situations, items for sales are generally stocked in a multiple of variations called stockkeeping units, such as size, color, style, and so on. For better management performance on sales items, proper and effective management is necessary for the stockkeeping units. In dealing with many items and those stockkeeping units, individual inventory analysis for each stockkeeping unit needs large amount of time or cost. Also the individual approach in inventory planning increases the demand variation of an item as the result by combining of demand variations of all stockkeeping units, accordingly the inventory turnover ratio and profitability are dropped down. This research suggests an effective method of systematic control of total stockkeeping units by generating from the total item basis, and shows how to reduce the safety stock and the average inventory with attaining a planned customer fill rate of the item and each stockkeeping units.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.4
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• pp.85-93
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• 2009

Bird strike is big issue in aviation. Because a bird strike causes not only an aircraft damage but also a fatality, aviation societies are gearing up to prevent a bird strike. However, the accidents is not going down yet. Annal average of bird strikes in Korea is 1.15 accidents per ten thousand of flight, which is lower than the other country, for example 1.84 accidents in France and 2.38 accidents in Switzerland, 1.15 accidents. In the U.S.A, there are 89,727 accidents for the 19 year(1990-2008). Also flight delay is total 637,692 hours. The cost is total 350,258 billion dollar and 18,435 billion dollar per year. In related with those data's, this research is about the current and legal status of the bird strike. Also it will be useful to establish aviation safety policy and manage the bird strike.

• Journal of Animal Science and Technology
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• v.58 no.1
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• pp.4.1-4.7
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• 2016

Background: This study was conducted to evaluate the effects of adding Korean rice wine residue (RWR) in total mixed ration (TMR) on in vitro ruminal fermentation and growth performance of growing Hanwoo steers. Methods: For in vitro fermentation, the experimental treatments were Control (Con: 0 % RWR + TMR), Treatment 1 (T1: 10 % RWR + TMR), and Treatment 2 (T2: 15 % RWR + TMR). The rumen fluid was collected from three Hanwoo steers and mixed with buffer solution, after which buffered rumen fluid was transferred into serum bottles containing 2 g dry matter (DM) of TMR added with or without RWR. The samples were then incubated for 0 h, 12 h, 24 h, or 48 h at $39^{\circ}C$ and 100 rpm. For the in vivo experiment, 27 Hanwoo steers (6 months old) with an average weight of $196{\pm}8.66kg$ were subjected to a 24-week feeding trial. The animals were randomly selected and equally distributed into three groups. After which the body weight, feed intake and blood characteristics of each group were investigated. Results: The pH of the treatments decreased significantly relative to the control during the 12 h of incubation. Total gas production and ammonia nitrogen ($NH_3-N$) was not affected by RWR addition. The total volatile fatty acid (VFA) was lower after 24 h of incubation but at other incubation times, the concentration was not affected by treatments. Feed cost was 8 % and 15 % lower in T1 and T2 compared to control. Blood alcohol was not detected and a significant increase in total weight gain and average daily gain were observed in Hanwoo steers fed with RWR. Conclusion: Overall, the results of this study suggest that TMR amended with 15 % RWR can be used as an alternative feed resource for ruminants to reduce feed cost.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.3
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• pp.1295-1301
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• 2015

Background: Cancer imposes a significant economic burden on individuals, families and society. The purpose of this study was to estimate the economic burden of cancer using the healthcare claims and cancer registry data in Korea in 2009. Materials and Methods: The economic burden of cancer was estimated using the prevalence data where patients were identified in the Korean Central Cancer Registry. We estimated the medical, non-medical, morbidity and mortality cost due to lost productivity. Medical costs were calculated using the healthcare claims data obtained from the Korean National Health Insurance (KNHI) Corporation. Non-medical costs included the cost of transportation to visit health providers, costs associated with caregiving for cancer patients, and costs for complementary and alternative medicine (CAM). Data acquired from the Korean National Statistics Office and Ministry of Labor were used to calculate the life expectancy at the time of death, age- and gender-specific wages on average, adjusted for unemployment and labor force participation rate. Sensitivity analysis was performed to derive the current value of foregone future earnings due to premature death, discounted at 3% and 5%. Results: In 2009, estimated total economic cost of cancer amounted to $17.3 billion at a 3% discount rate. Medical care accounted for 28.3% of total costs, followed by non-medical (17.2%), morbidity (24.2%) and mortality (30.3%) costs. Conclusions: Given that the direct medical cost sharply increased over the last decade, we must strive to construct a sustainable health care system that provides better care while lowering the cost. In addition, a comprehensive cancer survivorship policy aimed at lower caregiving cost and higher rate of return to work has become more important than previously considered.