• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.10
• /
• pp.4543-4549
• /
• 2011

In this study, software products developed in the course of testing, software managers in the process of testing software test and test tools for effective learning effects perspective has been studied using the NHPP software. The Burr distribution applied to distribution was based on finite failure NHPP. Software error detection techniques known in advance, but influencing factors for considering the errors found automatically and learning factors, by prior experience, to find precisely the error factor setting up the testing manager are presented comparing the problem. As a result, the learning factor is greater than automatic error that is generally efficient model could be confirmed. This paper, a numerical example of applying using time between failures and parameter estimation using maximum likelihood estimation method, after the efficiency of the data through trend analysis model selection were efficient using the mean square error and $R^2$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.37 no.2
• /
• pp.129-136
• /
• 2004

Visual line-transect surveys for the finless porpoise (Neophocaena phocaenoides) were conducted in the offshore of the west coast of Korea (WCOK) from 18 April to 17 May 2001 $(34^{\circ}18'\;to\;37^{\circ}18'N,\;123^{\circ}00'\;to\;126^{\circ}00'E),$ and in the inshore of the west coast of Korea (WCIK) from 29 July to 2 August 2003 $(35^{\circ}17'\;to\;36^{\circ}17'N,\;126^{\circ}00'\;to\;126^{\circ}25'E).$ A total of transect survey efforts were 810.27 n.m. in 2001 and 216.09 n.m. in 2003, which cover a survey areas of $23,012\;n.m^2\;and\;1,550\;n.m^2,$ respectively. There were 76 and 24 sightings for the finless porpoise during the surveys in the WCOK (2001) and the WCIK (2003), respectively. More than $80\%$ of the finless porpoise occurred near the coast within 15 n.m. from the land. Porpoise were observed mainly in a depth range from 20 to 50 m $(78\%).$ Few porpoise were observed in a depth shallower than 10 m or deeper than 60 m. The hazard-rate model, truncated at the largest $5\%$ distance, showed the best fitting from the frequency distribution of perpendicular distance of the finless porpoise sighted from the trackline in the WCOK (2001), while the uniform model showed the best fitting from in the WCIK (2003). Abundance of finless porpoises were estimated to be 58,650 individuals ($95\%$ CI=34,961-98,389) in the WCOK (2001) and 1,571 individuals ($95\%$ CI=881-2,800) in the WCIK (2003), respectively.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1106-1111
• /
• 2014

This paper has a purpose to find out the characteristics of pressure distribution according to the POD shape installed in the Hydrofoil vessel, using the CFD. The results showed that as we cut the POD cross-section's basic shape along the x-axis from 0 to 8cm, the viscous resistance had decreased, but then the pressure resistance had increased modestly. However, the cutoff length of POD cross-section shape has close to 9cm, the viscous drag had increased and the pressure drag had decreased. As a result, we found out that the pressure resistance made more effects in POD shape than the viscous resistance, and the total resistance decreased near the 9cm of cutoff length.

• The Korean Journal of Financial Management
• /
• v.14 no.1
• /
• pp.107-139
• /
• 1997

다른 금융산업과 마찬가지로 생명보험산업의 효율성에 대한 실증연구는 두 가지 문제에 봉착하게 된다. 하나는 효율성을 실증적으로 추정하는 다양한 추정방법은 일관되게 동일한 결과를 도출하는가 하는 것이며 다른 문제는 효율성추정에 사용된 생산물정의에서 어떤 대리변수를 사용하는 것이 가장 좋으냐 하는 것이다. Yuengert(1993)은 미국 생보산업 전체의 효율성과 추정방법간의 관계를 보고하였는데 본 연구는 추정방법 뿐만 아니라 생보산업 생산물의 정의에 따라 개별생보사의 효율성지수가 차이가 있다는 것을 248개의 미국 생명보험희사를 대상으로 검증하였다. 본 논문에서는 계량 경제학적 방법중 널리 사용되는 SFA(stochastic frontier approach)중에서 비효율성이 half-normal, truncated normal, exponential 분포라고 한 방법들과 비분포방법(DFA: distribution free approach)을 사용하였다. 또 각 방법마다 거수보험료(premiums)와 claims-plus-reserve라는 새로운 생산물 대리변수로 사용하여 효율성을 측정하였다. 그리하여 총 8가지의 다른 방법으로 추정한 효율성지수를 비교, 분석하였다. 연구결과 표1과 2에서 나타난 바와 같이 SFA방법(1, 3, 5번)간에는 결과가 거의 일치하였고 같은 추정방법에서 생산물 대리변수가 다른 경우에도(1과2, 3과4, 5와6, 7과8) 결과는 큰 차이가 없었다. 이는 생보산업에서 거수보험료를 생산물 대리변수로 하는 것이 이론적 문제가 있음에도 불구하고 구조적 편견(systematic bias)은 나타나지 않았다는 Suret(1991)의 결과를 지지하고 있다. DFA방법(7과 8번)과 SFA방법(1-6번)간에는 상관계수는 낮게 나타났는데 이는 생보산업의 효율성을 각각 DFA와 SPA방법을 사용한 두 연구(Gardner and Grace, 1993; Zi, 1994) 결과의 차이와 일치하고 있다.

• The Journal of the Korea Contents Association
• /
• v.11 no.3
• /
• pp.418-427
• /
• 2011

The purpose of this study is to investigate demand-determinant factors based on the number of visits and substitutive relations inter-restaurants, which are four major domestic family restaurants. Findings indicate that the factors of demand-determinant for visiting are affected by demographic characteristics, brand images of family restaurants, and the rate of the number of visits. In addition, this study used partial co-relation analysis to determine the substitutive relations of competitive restaurants. Considering these results, this study suggests how family restaurants' marketing strategy could be differentiated by discriminating the determinant factors which affect the number of visits. Also, this study makes it possible to arrange the opportunity to strengthen restaurants' competitiveness by examining competitive relations to the inter-restaurants.

• Health Policy and Management
• /
• v.6 no.2
• /
• pp.58-90
• /
• 1996

This study provides an empirical analysis of location competition for demand maximization by central place theory among physicians in nonmetropolitan areas of Korea. The results show that the primary care physicians distribute themselves evenly from urban communities to rural communities. The subspecialists, however, cluster together in major cities rather than decentralize themselves in rural counties. This study establishes the three statistical models : Primary care physicians, subspecialist physicians, and total physicians. Two models of primary care physicians and total physicians have a strong significance in multiple regression analysis (p=-.0001). The primary care model explains approximately 45% of the variation and the total physicians model explains approximately 70% of the variation in physician/1,000 population ratios across national counties. The subspecialist physicians model analysze the tobit regreassion because of the left consored and truncated values(57 cases = 0). In all three models, analysis of the coefficiencts for physician centralization degrees in the 0- to 5- and 5- to 10-km rings around the core county reveals each a positive and negative association betwee these degrees and the physician/1,000 population ratios in the core county. Also, the results provide moderate evidence that the relationship between clinic physicians and community hospitals is competitive, and the relationship between clinic physicians and pharmaceutists is synergistic. This suggests that public policy makers and local self-governing bodies must take an active role to ensure procider availability and the regional health planning in all nonmetropolitan areas of Korea.

• Journal of the Society of Naval Architects of Korea
• /
• v.48 no.3
• /
• pp.233-237
• /
• 2011

In the present experiments, vortical structures behind the hydrofoil trailing edge are visualized and analyzed as an elementary study for propeller singing phenomena. Two sorts of hydrofoil are selected for the measurement of shedding vortices. One was KH45 hydrofoil section and the other is KH45 with the truncated trailing edge that is positioned at X/C = 0.9523(C=chord length). Assuming the Strouhal number of 0.23, the shedding frequencies of vortices are extracted by analyzing the boundary layer thickness and the flow speed. The frequency distribution of shedding vortices is obtained with the variation of angle-of-attack while the flow speed is fixed to 8m/s. The truncation of the trailing edge makes the frequency of shedding vortices about 120Hz lower than that of original trailing edge and makes the vorticity value higher than the original trailing edge.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.10
• /
• pp.275-281
• /
• 2020

This study aims to explore a new approach of relationship assessment by partially employing attitudinal commitment to measure the influence on perception of cooperation within the Vietnamese rice supply chains, which begins from commercial enterprises up to the retailers in the Vietnamese market. The quantitative research is first built around the measurement instruments for the constructs of relationship quality (RQ) and its dimensions; next, a questionnaire is designed; finally, we deal with sample issues and analyze the data to answer the research questions. The truncated sampling technique and Likert-scale survey is a suitable method for analyzing Vietnamese rice retailers and data collection. The preliminary test was conducted using SPSS Statistics; the main test was, then, carried out to evaluate the proposed model and test the hypotheses. Appropriately, the results point to a significant influence of attitudinal factors on trust and satisfaction. In addition, with the involvement of perceived trust and satisfaction, that combination showed the mediating effect between the attitudinal factors and the relationship quality. The ad-hoc analysis indicated the significant role of the two mediators. To be more specific, the high degree of trust and satisfaction has a positive impact on the formation of the relationship between participants in the sector.

• Wind and Structures
• /
• v.13 no.3
• /
• pp.235-256
• /
• 2010

The aeroelastic stability of bridge decks equipped with multiple tuned mass dampers is studied. The problem is attacked in the time domain, by representing self-excited loads with the aid of aerodynamic indicial functions approximated by truncated series of exponential filters. This approach allows to reduce the aeroelastic stability analysis in the form of a direct eigenvalue problem, by introducing an additional state variable for each exponential term adopted in the approximation of indicial functions. A general probabilistic framework for the optimal robust design of multiple tuned mass dampers is proposed, in which all possible sources of uncertainties can be accounted for. For the purposes of this study, the method is also simplified in a form which requires a lower computational effort and it is then applied to a general case study in order to analyze the control effectiveness of regular and irregular multiple tuned mass dampers. A special care is devoted to mistuning effects caused by random variations of the target frequency. Regular multiple tuned mass dampers are seen to improve both control effectiveness and robustness with respect to single tuned mass dampers. However, those devices exhibit an asymmetric behavior with respect to frequency mistuning, which may weaken their feasibility for technical applications. In order to overcome this drawback, an irregular multiple tuned mass damper is conceived which is based on unequal mass distribution. The optimal design of this device is finally pursued via a full domain search, which evidences a remarkable robustness against frequency mistuning, in the sense of the simplified design approach.

• Journal of Korean Society for Quality Management
• /
• v.15 no.2
• /
• pp.10-19
• /
• 1987

Statistical control charts are useful tools to monitor and control the manufacturing processes and are widely used in most Korean industries. Many Korean companies, however, do not always obtain desired results from the traditional control charts by Shewhart such as the $\overline{X}$-chart, X-chart, $\widetilde{X}$-chart, etc. This is partly because the quality charterstics of the process are not distributed normally but are skewed due to the intermittent production, small lot size, etc. In the Shewhart $\overline{X}$-chart, which is the most widely used one in Korea, such skewed distributions make the plots to be inclined below or above the central line or outside the control limits although no assignable causes can be found. To overcome such shortcomings in nonnormally distributed processes, a distribution-free type of confidence interval can be used, which should be based on order statistics. This thesis is concerned with the design of control chart based on a sample median which is easy to use in practical situation and therefore properties for nonnormal distributions may be easily analyzed. Control limits and central lines are given for the more famous nonnormal distributions, such as Gamma, Beta, Lognormal, Weibull, Pareto, and Truncated-normal distributions.