• Communications for Statistical Applications and Methods
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• v.15 no.3
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• pp.421-427
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• 2008

This paper deals with the problem of testing for the existence of change in mean and estimating the change-point when the data are from the exponential distributions. The likelihood ratio test statistic and Gombay and Horvath (1990) test statistic are compared in a power study when there exists one change-point in the exponential means. Also the change-point estimator using the likelihood ratio and the change-point estimators based on Gombay and Horvath (1990) statistic are compared for their detecting capability via simulation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.2
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• pp.72-81
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• 2015

This paper studied the differences of the inventories asset turnover change ratio and several characteristics variable between large and small manufacturing firm group. Large and small firm group were determined based on number of labors and asset size. Several characteristics variable of firms such as assets size, sales growth rate, return on assets, leverage ratio, credit rating and age of firm were used to find out the differences of firm group. As a result, the inventory asset turnover change ratio of large firm was 5.16% and that of the middle and small firm was 9.3%. For the large firm, sales growth rate, ROA and credit rating affect inventory assets turnover change ratio. For the middle and small sized firm, Assets size, sales growth rate and credit rating affect inventory assets turnover change ratio. Using this result, we can say that manufacturing company need to consider their firm size and their characteristics to make their own operation strategy of inventory.

• The Journal of the Korean life insurance medical association
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• v.7 no.1
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• pp.170-179
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• 1988

A study on the change of cardiothoracic ratio by age calculated from photofluorography film of chest in a total of the 8,115 insureds was undertaken. The results were as follows: 1. The incidence of cardiothoracic ratio of high value increased gradually with age. 2. At the same build, the average cardiothoracic ratio increased gradually with age. 3. Larger the build index was, the incidence of higher cardiothoracic ratio increased. 4. It seemed that the change of cardiothoracic ratio by age was influenced mainly by age and build(the change of build by age) from $18{\sim}19$ to $40{\sim}49$ age group and by age itself in $50{\sim}59$ age group and over. 5. The average cardiothoracic ratio of $30{\sim}39$ age group in male or female was approximate to that of all ages group respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.7-12
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• 2017

It is assumed that the buckling and cutting conditions depending on the slenderness ratio will affect the machining quality of the rotary boring tool mounted on a milling machine. In this study, the boring cutter was designed and fabricated to precisely create the Ø30 hole. Through the performance evaluation, the accuracy of the hole according to the slenderness ratio and cutting conditions was analyzed, and the following conclusions were obtained. The higher the RPM, the smaller the change in the working diameter, and the smaller the hole. Next, the smaller the slenderness ratio, the smaller the change in straightness due to the change in cutting conditions. Finally, the slenderness ratio also affects the tendency for changes in the concentricity. The larger the slenderness ratio, the more sensitive the concentricity to changes in cutting conditions.

• Journal of the Korean Data and Information Science Society
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• v.17 no.4
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• pp.1091-1098
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• 2006

Park et al.(2005) and Choi et al.(2006) studied quick detection of variance change point for time series data in progress. For efficient detection they used moving variance ratio equipped with two tuning parameters; information tuning parameter p and lag tuning parameter q. In this paper, the moving variance ratio is studied under harsh conditions.

• Journal of Marine Life Science
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• v.9 no.1
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• pp.41-46
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• 2024

This study aimed to reconfirm the sex change scale and pattern of Tegillarca granosa. Although the sex ratio (female : male, female proportion) of T. granosa was 1:2.32 (30.2%) at the initial stage (2011) of the study, it was 1:0.94 (51.5%) after one year (2012) in the same population. The increase of the female proportion was greater in the 2+ year class (23.0%) when compared to the 1+ year class (19.2%). Overall, sex change ratio of 37.6% was observed in this population of T. granosa. The sex change ratio of the 2+ year class (39.3%) was higher than that of the 1+ year class (35.3%). And sex change ratio in the males (42.2%) was higher than that in the females (26.9%). The female proportion was the opposite of the result from 2006~2007, and one of the causes was presumed to be the difference in cumulative water temperature during the gonadal inactive stage (winter).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.11
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• pp.1390-1398
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• 1999

A numerical analysis for ROT sparger of PWR(Pressurized Water Reactor) is carried out. Computation is performed to investigate the flow characteristics as the change of design factor. As the result of this study, RDT sparger's flow resistance coefficient is K=3.53 at the present design condition if engineering mar&in is considered with 20%, and flow ratio into branch pipe is $Q_s/Q_i=0.41$. Velocity distribution at exit is not uniform because of separation in branch pipe. In the change of inlet flow rate and section area ratio of branch pipe for main pipe, flow resistance coefficient is increased as $Q_s/Q_i$ decreasing, but in the change of branch angle and outlet nozzle diameter of main pipe, flow resistance coefficient is decreased as $Q_s/Q_i$ decreasing. As the change rate of $Q_s/Q_i$ is the larger, the change rate of flow resistance coefficient is the larger. The change rate of pressure loss is the largest change as section area ratio changing. The optimal design condition of sparger is estimated as the outlet nozzle diameter ratio of main pipe is $D_s/D_i=0.333$, the section area ratio is $A_s/A_i=0.2$ and the branch angle is ${\alpha}=55^{\circ}$.

• Korean Journal of Remote Sensing
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• v.26 no.3
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• pp.287-295
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• 2010

Water level of the Tonle Sap is largely influenced by the Mekong River. During the wet season, the lacustrine landform and vegetated areas are covered with water. Change detection in this area provides information required for human activities and sustainable development around the Tonle Sap. In order to detect the changes in the Tonle Sap floodplain, fifteen ALOS-PALSAR L-band data acquired from January 2007 to January 2009 and examined in this study. Since L-band is able to penetrate into vegetation cover, it enables us to study the changes according to water level of floodplain developed in the rainforest. Four types of images were constructed and studied include 1) ratio images, 2) correlation coefficient images, 3) texture feature ratio images and 4) multi-color composite images. Change images (in each 46 day interval) extracted from the ratio images, coherence images and texture feature ratio images were formed for detecting land cover change. Two RGB images are also obtained by compositing three images acquired in the early, in the middle and at the end of the rainy season in 2007 and 2008. Combination of the methods results that the change images present the relationship between vegetation and water level, leaf fall forest as well as cultivation and harvest crop.

• Journal of the Korean Dietetic Association
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• v.6 no.1
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• pp.33-43
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• 2000

Environmental pressures from such sources an economic condition, the government and inter-institutional competition create managerial challenges. Economic pressures may be forcing dietetic dept, in hospital to utilize cost∙benefit analysis to assist them in their problem solving. Cost∙benefit analysis have been widely used in business, industry and many other fields with only limited application to foodservice. Due to the lack or this information the purposes of this study were to identify use of cost∙benefit analysis in hospital foodservice system to evaluate the economic efficiency of alternatives, and to make recommendation for operation system change. Using the cost∙benefit method, cash flows are separated into cost and benefits. For an alternative to be selected, indicators, such as NPV, benefit-cost ratio (B/C ratio) with 5% discount rate per annum. The sensitivity analysis was also conducted with difference rate 3%, 7% respectively and reduced employee payroll change. The result of this study can be summarized as follows : 1. The total cost of investment for operation system change was 390,570 thousand won and the total benefit through operation system change was 865,808 thousand won. 2. Net present value(NPV) for 5 years was 475,239 thousand won and benefit-cost ratio was 2.22. 3. In sensitivity analysis with different discount rate 3%, 7%, benefit-cost ratio was 2.25, 2.18 respectively, with total reduced employee payroll change, benefit-cost ratio was 2.86. In conclusion, total benefits were exceeded total costs. Therefore, the project of operation system change in hospital foodservice was found to be economically efficient.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.1
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• pp.34-42
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• 2012

This study aims to suggest the secure indicator of parks and green areas according to the properties of the location. There were 31 study areas where negotiation was finalized from 2001 to 2008. The location types were divided by land use type before development and the ratio of mountainous and constructed parks, the ratio of green change and so forth were analyzed according to the those types. As a result, location types were classified into mountainous type, arable land type, urban district type. In terms of locational property, even though the ratio of parks and green areas was the highest at 24.9% in arable land type, the ratio was not much different from the others. Mountainous type depends on the ratio of mountainous park with 10.5%, and arable land type, and urban district type has high ratio of constructed parks. And, the ratio of green change arable land type is degraded by 32.8% and the ratio of mountainous green change is serious in the mountainous type. As a result of the selection of negotiation indicator, arable land type is closely related to the ratio of parks and green areas and the ratio of green change; mountainous type, the ratio of park and green, the ratio of mountainous green change and the ratio of constructed park and green; urban district type, the ratio of green areas.