• Journal of Korean Society of Transportation
• /
• v.25 no.3
• /
• pp.137-144
• /
• 2007

This study involves an analytical approach to determine transit dispatching schedules (headways) Determining a time schedule is an important process in transit system planning. In general, the transit headway should be shorter during the peak hour than at non-peak hours for demand-responsive service. It allows passengers to minimize their waiting time under inelastic, fixed demand conditions. The transit headway should be longer as operating costs increase, and shorter as demand and waiting time increase. Optimal headway depends on the amount of ridership. and each individual vehicle dispatching time depends on the distribution of the ridership. This study provides a theoretical foundation for the dispatching scheme consistent with common sense. Previous research suggested a dispatching scheme with even headway. However, according to this research, that is valid for a specific case when the demand pattern is uniform. This study is a general analysis expanding that previous research. This study suggests an easy method to set a time table without a complex and difficult calculation. Further. if the time axis is changed to the space axis instead, this study could be expanded to address the spacing problems of some facilities such as roads. stations, routes and others.

• Journal of the Economic Geographical Society of Korea
• /
• v.17 no.3
• /
• pp.538-553
• /
• 2014

The aim of this study is to consider the degree of supply-demand balance in relation to the characteristics of retail sale activities in depopulation aging regions and the degree of aging by using simple regression analysis. The major findings of this study are as follows. While aging society, and aged society regions show a similar major retail sale industries, super-aged society shows fewer major industries and different industry composition. These characteristics are seen by different phenomenon and the background of the particular retail structure. The first one is that the number of employees per establishment increases when the aging phenomenon is not accelerated, and the annual sales per capita purchasing power decrease because their purchasing power becomes lower when the aging phenomenon is severe, but it also shows a high density of establishments because disperse location of establishment within depopulation aging region. The second one is the retail structure with high labor productivity in a aged and superaged society region. We identify the extent of demand and supply in general retails, fuel retails, food and beverage, and tobacco retails which represent the highest sales rates in depopulation aging region. As a result, general retails are seen as 'supply-demand balance region' in aged and super-aged society, fuel retail sales in aged and super-aged society which generally shows less sales, and food and beverages, and tobacco retails in super-aged society. The higher the degree of aging is, the less the regional differences in the gap between demand and supply is. This is because the difference in purchasing power between these regions is small.

• Journal of Korean Society of Transportation
• /
• v.30 no.2
• /
• pp.29-42
• /
• 2012

Recently, traffic congestion has become serious due to increase of private car usages. Carsharing or other innovative public transportation systems were developed to alleviate traffic congestion and carbon emissions. These measures can make the traffic environment more comfortable, and efficient. Cloud Transportation System (CTS) is a recent carsharing model. User can rent an electronic vehicles with various traffic information through the CTS. In this study, a concept, vision and scenarios of CTS are introduced. And, authors analyzed the location of CTS rental stations and estimated CTS demands. Firstly, we analyze the number of the population, employees, students and traffic volume in study areas. Secondly, the frequency and utilization time are examined. Demand for CTS in each traffic zone was estimated. Lastly, the CTS rental station location is determined based on the analyzed data of the study areas. Evaluation standard of the determined location includes accessibility and density of population. And, the number of vehicles and that of parking zone at the rental station are estimated. The result suggests that Haewoondae Square parking lot would be assigned 11 vehicles and 14.23 parking spaces and that Dongbac parking lot be assigned 7.9 vehicles and 10.29 parking spaces. Further study requires additional real-time data for CTS to increase accuracy of the demand estimation. And network design would be developed for redistribution of vehicles.

• Journal of the Korean Solar Energy Society
• /
• v.26 no.4
• /
• pp.83-91
• /
• 2006

As a demand for sustainable development rises, the preference for earth house (earth construction) increases gradually. However, there are few data for predicting and evaluating the thermal environment and indoor air quality of earth house. Thus, this study aims to measure thermal properties(thermal conductivity, density and specific heat) and pollutants emission intensities(formaldehyde and volatile organic compounds) of current main earth construction materials and make a comparison between earth and cement construction materials. As results, quantitative thermal properties and pollutants emission intensities of current main earth construction materials are shown.

• The Korean Journal of Malacology
• /
• v.29 no.4
• /
• pp.283-289
• /
• 2013

In order to improve oyster farming condition, estimation of food availability (CC) was carried out in Garorim Bay, Seosan, Korea. The primary production of the waters were ranged from 0.07 to $0.26gC/m^2/day$. A strong tendency was observed that the inner side of the bay was higher at primary production. Estimated food availability was ranged from 0.0424 to 1.655. Temporal shortage in food supply was observed at April with about 15% less than the oysters' requirement, which may be causative of spat mortality after introducing into the farms. Food availability was met the food demand during summer but significant shortage was also observed at after August, which may main causative of retarded oyster fattening in the waters. This study suggested that adjustment of cultural density may be necessary for the improved harvesting of the oyster.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.1
• /
• pp.90-96
• /
• 2009

Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. Today, injection molded parts have been increased dramatically the demand for high strength and quality applications. This report investigates that the optimum injection molding condition for minimum of shrinkage. Molding shrinkage is occurred by several reasons such as thermal shrinkage, a hardening process and compressibility. This report concentrate on shrinkage by a hardening process. As Change a holding pressure and holding time, checked deflections of X, Y, Z directions by shrinkage based on same condition. In conclusion, it was found that holding pressure is stronger and holding time is longer, the deflection by shrinkage is smaller because injection molding needs enough time for cooling and high density. The FEM Simulation CAE tool. Moldflow, is used for the analysis of injection molding process.

• Korean Journal of Organic Agriculture
• /
• v.14 no.3
• /
• pp.287-303
• /
• 2006

This paper describes the market development and marketing strategy of organic products in European Union(EU), where organic products market has grown rapidly due to a variety of factors. According to several surveys environmentally friendly agricultural products widely meet consumers demand, but the corresponding market share in Korea is less than 4.0%. Missing confidence in the authenticity of organic products, high prices compared to other foods, a low density of distribution, and a lack of a uniform label are regarded as hampering factors for market growth. The influence of the image of organic products on market development, however, is analyzed insufficiently by now. This paper therefor aims at investigating the implications of the marketing strategy and image of organic foods on its acceptance by consumers and deriving hints for the development of the market. The actual study is based on a concept of morphological market research, the result refer to Germany, Swiss, Austria.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.510-515
• /
• 2004

A proton exchange membrane fuel cells(PEMFC) operate at low temperature, allowing for faster startups and immediate response to change in the demand for power, and also deliver high power density. To maximize economical efficiency in PEMPC, it is necessary to the optimization. Response surface method(RSM) has non-gradient and fast convergency characteristics. Sampling points are extracted by design of experiments using Central Composite Method. In this paper, it is shown that the optimization is required for the design study of the PEMFC.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.11
• /
• pp.875-881
• /
• 2003

The received signal of a mobile phone is normally sensed through two independent means which are the sound generation of a speaker and vibration generation of a vibration motor. As an improvement scheme to meet the consumer's demand on weight reduction and miniaturization of a mobile phone, the design and development of an integrated vibration and sound generating device are performed in this research. To this purpose, the optimal shapes of the voice coil. the permanent magnet and the vibration plate are designed, and the excitation force applied to the vibration system of the new device is estimated and verified through theoretical analyses, computer simulation, and experiments using an expanded model. In addition, vibration performance comparison of the device with the existing vibration motor is performed, and from the overall process, therefore, the method and procedure for the vibration performance analysis of the integrated vibration and sound generating device are established.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.181-186
• /
• 2002

Lately, as going on increasing in the demand of high power density(power/weight), it is necessary for hydraulic axial piston pump/motor to operate more high pressure and speed. But in these condition, there are some trouble like as friction loss. To reduce this friction loss, hydrostatic bearing is used far axial piston pump/motor frequently. In general, it is difficult to measure accurate friction torque of spherical hydrostatic bearing in the use of the existing devices. So, we have developed the measurement device using the reaction torque sensor to obtain the pure friction torque, fitted in the casing. In this report, we intend to make an introduction about this measurement device for friction torque of the spherical wear part and clarify the effect of friction characteristics on supply pressure and rotational speed with three types of pocket size by using this measurement device.