• Journal of Distribution Science
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• v.10 no.5
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• pp.37-44
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• 2012

In this paper, we investigate several factors that affect the locational decision of discount stores by using previous studies on the marketing area and the location of commercial facilities. We selected 21 primary variables that are expected to influence the decision of store location and, by factor analysis, grouped them into five underlying factors. Among these, the demographic factor, which shows the potential purchasing power level, had the greatest impact on the locational decision for the store. However, we found individual stores positioned according to unique locational characteristics in addition to the demographic factor. It means that we have to additionally consider if the vicinity of the market is based on any physical properties. Many previous studies proposed four decision factors for store location: the economic factor, the demographic factor, the land utilization factor, and traffic factor. However, the fivefold factors-our distinctive contribution-are more concrete and persuasive according to Korean reality. We show that location preference is based on the following criteria: (1) the area is densely populated, (2) houses stand close together, (3) residents have a high income level, (4) road traffic is developed and easy to access, and (5) public transportation is well developed. The demographic factor has the greatest impact on the location of a discount store. The number of households has a greater relevance to the demographic factor than does the individual consumer. Second, discount stores relatively prefer places where houses are located close together because such places offer easy access to the market. Third, a place whose residents have a high income level will be preferred, with its large cars and excellent traffic conditions. Fourth, a location would be highly rated if the roads around commercial facilities are well developed and their accessibility is good. Finally, discount stores must be located close to bus stops because female consumers, including housewives-the most important customers-evaluate stores based on distance. In this research, the variable of consumer attitude and preference was excluded, and the location factors of discount stores were analyzed according to a microscopic view through physical spatial data. In the future, the opening of new discount stores based on the five factors indicated above will require a comparatively shorter time from the first project feasibility analysis. In addition, the result of our study can be applied to the field of public policy for constructing and attracting large-scale distribution facilities.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.711-722
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• 2011

Beam-column gravity or Intermediate Moment frames subjected to unexpected large displacements are vulnerable when no seismic details are provided, which is typical. Conversely, economic efficiency of those frames is decreased if unnecessary special detailing is applied as the beam and column size becomes quite large and steel congestion is caused by joint transverse reinforcement in beam-column connections. Moderate seismic design is used in Korea for beam-column connections of buildings with structural walls, which are to be destroyed when the unexpected large earthquake occurs. Nonetheless, performance of such beamcolumn connections may be substantially improved by the addition of steel fibers. This study was conducted to investigate the effect of steel fibers in reinforced concrete exterior beam-column connections and possibility for the replacement of some joint transverse reinforcement. Ten half-scale beam-column connections with non-seismic details were tested under cyclic loads with two cycles at each drift up to 19 cycles. Main test parameters used were the volume ratio of steel fibers (0%, 1%, 1.5%) and joint transverse reinforcement amount. The test results show that maximum capacity, energy dissipation capacity, shear strength and bond condition are improved with the application of steel fibers to substitute transverse reinforcement of beam-column connections. Furthermore, several shear strength equations for exterior connections were examined, including the proposed equation for steel fiber-reinforced concrete exterior connections with non-seismic details.

• KDI Journal of Economic Policy
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• v.30 no.2
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• pp.225-270
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• 2008

We analyze macroeconomic consequences of pay-as-you-go (PAYGO) public pension system with a simple overlapping generations model. Contrary to large body of existing literatures offering quantitative results based on simulation study, we take another route by adopting a highly simplified framework in search of qualitatively tractable analytical results. The main contribution of our results lies in providing a sound theoretical foundation that can be utilized in interpreting various quantitative results offered by simulation studies of large scale general equilibrium models. We present a simple overlapping generations model with a defined benefit(DB) PAYGO public pension system as a benchmark case and derive an analytical equilibrium solution utilizing graphical illustration. We also discuss the modifications of the benchmark model required to encompass a defined contribution(DC) public pension system into the basic framework. Comparative statics analysis provides three important implications; First, introduction and expansion of the PAYGO public pension, DB or DC, result in lower level of capital accumulation and higher expected rate of return on the risky asset. Second, it is shown that the progress of population aging is accompanied by lower capital stock due to decrease in both demand and supply of risky asset. Moreover, risk premium for risky asset increases(decreases) as the speed of population aging accelerates(decelerates) so that the possibility of so-called "the great meltdown" of asset market cannot be excluded although the odds are not high. Third, it is most likely that the switch from DB PAYGO to DC PAYGO would result in lower capital stock and higher expected return on the risky asset mainly due to the fact that the young generation regards DC PAYGO pension as another risky asset competing against the risky asset traded in the market. This theoretical prediction coincides with one of the firmly established propositions in empirical literature that the currently dominant form of public pension system has the tendency to crowd out private capital accumulation.

• Journal of dental hygiene science
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• v.4 no.3
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• pp.91-95
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• 2004

This study aims to analyze realities of oral health and related factors, and establish Structural Equation Modeling. The subjects of study were 9,340 elderly over age 65 who took the health examination(the first) for the local insured which National Health Insurance Corporation carried out in the survey area mentioned below from January 2002 to December 2002. The areas surveyed were 4 big cities including Seongbuk-ku, Seoul, 5 medium cities including Wonjusi, Gangwon-do, and 5 Counties including Yeong deok County, Kyeongbuk. Considering location and the scale of population, firstly, big unit areas(metropolitan city, province) were selected according to convenience, secondly, low unit areas(city, county, district) were selected randomly. The subjects were the elderly who took all tests including an oral examination and filled in the questionnaire. Major results from analysis are as follows: 1. Review of Composition Conception Validity As a result of analyzing composition conception validity of SEM including posture test, urine test, blood test, habits of eating, drinking and smoking, oral symptoms, and oral health status, using fit index such as GFI, CFI, TLI, and RMSEA, all were within fit range and composition conception validity was recognized. 2. As a result of analyzing SEM to find the relationship between each factor and oral health status, it was confirmed that all factors except urine test affected oral health status and the synthetic SEM to explain it could be established. In result, we could verify that the elderly of rural areas who had lesser experience of visiting a clinic and oral prophylaxis had a higher rate of caries, missing teeth, and denture need, and drinking and smoking negatively affected the rate of caries, periodontal, and missing teeth. Also, periodontal diseases were observed from 43.2% of the total elderly and much from the lower age. Most of oral disease can be prevented by right oral health behavior. Therefore through oral health professionals from each district public health center of the nation, oral health education for the elderly about right eating habits and oral health care should be carried out systematically and policy change to increase access to dental service is required lest that visiting a dental clinic should be impossible or oral health behaviors such as oral prophylaxis and denture wearing should be neglected by economic, geographical barriers. Also, to establish SEM to explain the relationship between oral health status and systemic health, more accurate test methods and effective index development should be preceded. Because items developed by National Health Insurance Corporation applied to this study without alteration, structuring a model had the uppermost limit. Continual study seems to be needed.

• KDI Journal of Economic Policy
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• v.12 no.2
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• pp.51-79
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• 1990

Research on technical efficiency, an important dimension of market performance, had received little attention until recently by most industrial organization empiricists, the reason being that traditional microeconomic theory simply assumed away any form of inefficiency in production. Recently, however, an increasing number of research efforts have been conducted to answer questions such as: To what extent do technical ineffciencies exist in the production activities of firms and plants? What are the factors accounting for the level of inefficiency found and those explaining the interindustry difference in technical inefficiency? Are there any significant international differences in the levels of technical efficiency and, if so, how can we reconcile these results with the observed pattern of international trade, etc? As the first in a series of studies on the technical efficiency of Korea's manufacturing industries, this paper attempts to answer some of these questions. Since the estimation of technical efficiency requires the use of plant-level data for each of the five-digit KSIC industries available from the Census of Manufactures, one may consture the findings of this paper as empirical evidence of technical efficiency in Korea's manufacturing industries at the most disaggregated level. We start by clarifying the relationship among the various concepts of efficiency-allocative effciency, factor-price efficiency, technical efficiency, Leibenstein's X-efficiency, and scale efficiency. It then becomes clear that unless certain ceteris paribus assumptions are satisfied, our estimates of technical inefficiency are in fact related to factor price inefficiency as well. The empirical model employed is, what is called, a stochastic frontier production function which divides the stochastic term into two different components-one with a symmetric distribution for pure white noise and the other for technical inefficiency with an asymmetric distribution. A translog production function is assumed for the functional relationship between inputs and output, and was estimated by the corrected ordinary least squares method. The second and third sample moments of the regression residuals are then used to yield estimates of four different types of measures for technical (in) efficiency. The entire range of manufacturing industries can be divided into two groups, depending on whether or not the distribution of estimated regression residuals allows a successful estimation of technical efficiency. The regression equation employing value added as the dependent variable gives a greater number of "successful" industries than the one using gross output. The correlation among estimates of the different measures of efficiency appears to be high, while the estimates of efficiency based on different regression equations seem almost uncorrelated. Thus, in the subsequent analysis of the determinants of interindustry variations in technical efficiency, the choice of the regression equation in the previous stage will affect the outcome significantly.

• Journal of the Korean Institute of Navigation
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• v.4 no.2
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• pp.45-79
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• 1980

The aim of this paper is to analyze the mechanics of price formation in the tramp shipping. For the purpose of this study, the main characteristics of tramp freight rates and the market is examined, and a brief examination of the nature ofthe costs of operation is given which are essential for the understanding of the functioning of shipping firms as well as for the understanding of developments in the tramp freight market. The demand and supply relationships in the market is also analysed in detail. Tramp shipping is an industry that has a market which functions under conditions that are not dissimilar to the theoretical model of perfect competition. However, it does notmean that tramp shipping market is a perfectly competitive market. It is apparent that this realworld competitive system has its imperfections, which means that the market for tramp shipping is near to being a perfectly competitive market on an internaitonal scale and it is freight are therefore subjext to the laws of supply and demand. In theory, the minimum freight rate in the short term is that at which the lowest cost vessels will lay-up in preference to operating, and is equal to the variable costs minus lay-up costs; and this would imply that in all times except those of full employment for ships there is a tendency for newer low-cost, and, probably, faster vessels to be driving the older high-cost vessels in the breaker's yards. In this case, shipowners may be reluctant to lay-up their ships becasue of obligations to crews, or because they would lose credibility with shippers or financiers, or simply because of lost prestige. Mainly, however, the decision is made on strictly economic grounds. When, for example, the total operating costs minus the likely freight earnings are greater than the cost of taking the ship out of service, maintaining it, and recommissioning it, then a ship may be considered for laying-up; shipowners will, in other words, run the ships at freight earnings below operating costs by as much as the cost of laying them up. As described above, the freight rates fixed on the tramp shipping market are subject to the laws of supply and demand. In other words, the basic properties of supply and demand are of significance so far as price or rate fluctuations in the tramp freight market are concerned. In connection with the same of the demand for tramp shipping services, the following points should be brone in mind: (a) That the magnitude of demand for sea transport of dry cargoes in general and for tramp shipping services in particular is increasing in the long run. (b) That owning to external factors, the demand for tramp shipping services is capable of varying sharphy at a given going of time. (c) The demad for the industry's services tends to be price inelastic in the short run. On the other hand the demand for the services offered by the individual shipping firm tends as a rule to be infinitely price elastic. In the meantime, the properties of the supply of the tramp shipping facilities are that it cannot expand or contract in the short run. Also, that in the long run there is a time-lag between entrepreneurs' decision to expand their fleets and the actual time of delivery of the new vessels. Thus, supply is inelastic and not capable of responding to demand and price changes at a given period of time. In conclusion, it can be safely stated that short-run changes in freight rates are a direct result of variations in the magnitude of demand for tramp shipping facilities, whilest the average level of freight rates is brought down to relatively low levels over prolonged periods of time.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.4
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• pp.36-48
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• 2018

This study surveyed 599 elementary schools in Seoul to provide measures for the quantitative expansion and sustainable operation of environmentally-friendly school garden. Of all schools, 161 schools had formed and were operating school gardens. The total area of school gardens was $166,901m^2$ and the mean area was $131.2m^2$ in elementary, junior high and high schools in Seoul. Meanwhile, the total area of school gardens was $65,493m^2$ and the mean area was $363m^2$ in 161 schools that participated in the survey, indicating $1.15m^2$ per student. Of these schools, 11.8% were operating gardens themselves, while 50.3% were operating gardens that had been newly renovated or environmentally improved by institutional support projects after initially managing gardens themselves. According to the locations of school gardens, mixed-type gardening (a combination of school gardening and container vegetable gardening) accounted for 34.8%, followed by school gardening at 32.9%, container vegetable gardening at 29.2%, and suburb community gardening at 3.1%. Those in charge of garden operations were teachers at 51.6%, comprising the largest percentage. Facilities built when forming the garden included storage facilities for small-scale greenhouses and farming equipment at 26.1%, accounting for the largest percentage. No additional facilities constructed accounted for 21.7%. The greatest difficulty in operating gardens was garden management at 34.2%. The most needed elements for the sustainable operation of gardens were improvement in physical environment and the need for hiring a paid garden, each accounting for 32%. The most important purpose for school gardening was creating educational environments (81.6%). The major source for gaining information on garden management was consultation from acquaintances (67.8%). Schools that utilize plant waste from gardens as natural fertilizers accounted for 45.8% of all schools. Responses to the impact of operating school gardens for educational purpose were positive in all schools as 'very effective' in 63.2% and 'effective' in 36.8%. This study was meaningful in that it intended to identify the current status of the operation of school gardens in elementary schools in Seoul, support the formation of school gardens appropriate for each school with sustainable operation measures, implement a high-quality education program, develop teaching materials, expand job training opportunities for teachers in charge, devise measures to support specialized instructors, and propose the need for a garden management organization.

• Korean Journal of Food Science and Technology
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• v.7 no.3
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• pp.128-134
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• 1975

For development of long-term storage method of sweet-persimmons using polyethylene film bags, basic experiment was conducted with 30 boxes of sweet-persimmons in 1973 and the same experiment was extended for industrial application with 2,500 boxes of the persimmons in the cold storage of Jinyoung Sweet-persimmon Association in 1974. Investigation was made on change of the quality by storage period. At the same time, persimmons put in the cold storage test were shipped to market at different time in order to monitor consumer response and commercial feasibility. The followings are conclusion obtained from the result of this experiment. 1. Storage of sweet-persimmon, Buyu, produced in Jinyoung, Kimhae was possible for 1 month at $2^{\circ}C{\pm}1^{\circ}C$ cold storage. This storage period was extended to 4 months until the end of February in case that the fruits were hermetically sealed in P.E. film bags of 0.08 to 0.1 mm thickness. 2. During the storage period of sweet-persimmons packed in the film bags, the loss of weight due to evaporation was effectively prevented with use of the film of bag thicker than 0.04 mm. 3. The storage ability of 3-5 persimmons per small bag was somewhat superior to that of many persimmons packed in the large box of 15kg capacity. 4. The thicker the film of bags, the more $CO_2$ gas was accumulated inside, however, from 1 month after beginning of the storage the rate of $CO_2$ accumulation became very low maintaining the stabilized level of 5-6% at the plot of 0.06-0.08mm thick bags. 5. While the persimmons were in storage, decreased was the content of total sugars, total acids, and vitamin C, of which the phenomenon was remarkable especially with the fruits of non-packed plot. 6. The sweet-persimmons in the film bags subjected to cold storage when shipped to market in their intact condition were more beneficial than when they were shipped out in unpacked condition. The intact fruits packed in the P.E. film bags were able to keep their commercial value for 10days in the outdoor situation. 7. The sweet-persimmons that were packed in the film bags and put in the cold storage had maintained promissing marketability and the economic feasibility was acknowledged when the experimental practice was applied to industrial scale.

• Fire Science and Engineering
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• v.31 no.5
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• pp.53-62
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• 2017

Electric power which is the energy source of economy and industries requires long distance transportation due to regional difference between its production and consumption, and it is supplied through the multi-loop transmission and distribution system. Prior to its actual use, electric power flows through several transformations by voltage transformers in substations depending on the characteristics of each usage, and a transformer has the structure consisting of the main body, winding wire, insulating oil and bushings. A transformer fire that breaks out in substations entails the primary damage that interrupts the power supply to houses and commercial facilities and causes various safety accidents as well as the secondary economic losses. It is considered that causes of such fire include the leak of insulating oil resulting from the destruction of bottom part of bushings, and the chain reaction of fire due to insulating oil that reaches its ignition point within 1 second. The smoke detector and automatic fire extinguishing system are established in order to minimize fire damage, but a difficulty in securing golden time for extinguishing fire due to delay in the operation of detector and release of gas from the extinguishing system has become a problem. Accordingly, this study was carried out according to needs of active mechanism to prevent the spread of fire and block the leak of insulating oil, in accordance with the importance of securing golden time in extinguishing a fire in its early stage. A bushings fireproof structure was developed by applying the high temperature shape retention materials, which are expanded by flame, and mechanical flame cutoff devices. The bushings fireproof structure was installed on the transformer model produced by applying the actual standards of bushings and flange, and the full scale fire test was carried out. It was confirmed that the bushings fireproof structure operated at accurate position and height within 3 seconds from the flame initiation. It is considered that it could block the spread of flame effectively in the event of actual transformer fire.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.6
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• pp.256-268
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• 2016

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2015. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering were carried out in the areas of flow, heat and mass transfer, cooling and heating, and air-conditioning, the renewable energy system and the flow inside building rooms. Research issues dealing with air-conditioning machines and fire and exhausting smoke were reduced. CFD seems to be spreading to more research areas. (2) Research works on heat transfer area were carried out in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the economic analysis of GHG emission, micro channel heat exchanger, effect of rib angle on thermal performance, the airside performance of fin-and-tube heat exchangers, theoretical analysis of a rotary heat exchanger, heat exchanger in a cryogenic environment, the performance of a cross-flow-type, indirect evaporative cooler made of paper/plastic film. In the area of pool boiling and condensing, the bubble jet loop heat pipe was studied. In the area of industrial heat exchangers, researches were performed on fin-tube heat exchanger, KSTAR PFC and vacuum vessel at baking phase, the performance of small-sized dehumidification rotor, design of gas-injection port of an asymmetric scroll compressor, effect of slot discharge-angle change on exhaust efficiency of range hood system with air curtain. (3) In the field of refrigeration, various studies were carried in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, a cold-climate heat pump system, $CO_2$ cascade systems, ejector cycles and a PCM-based continuous heating system were investigated. In the alternative refrigeration/energy system category, a polymer adsorption heat pump, an alcohol absorption heat pump and a desiccant-based hybrid refrigeration system were investigated. In the system control category, turbo-refrigerator capacity controls and an absorption chiller fault diagnostics were investigated. (4) In building mechanical system research fields, eighteen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the user and location awareness technology applied dimming lighting control system, the lighting performance evaluation for light-shelves, the improvement evaluation of air quality through analysis of ventilation efficiency and the evaluation of airtightness of sliding and LS window systems. The subjects of building energy were worked on the energy saving estimation of existing buildings, the developing model to predict heating energy usage in domestic city area and the performance evaluation of cooling applied with economizer control. The studies were also performed related to the experimental measurement of weight variation and thermal conductivity in polyurethane foam, the development of flame spread prevention system for sandwich panels, the utilization of heat from waste-incineration facility in large-scale horticultural facilities.