• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.781-787
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• 2010

Forecasting possible failure characteristics is very important in maintenance planning because it helps in predicting any future failures and determining the optimum replacement interval. This paper examines the time.to-failure distribution of the transfer gearbox of a J79 engine by using a probability plotting technique which is one of the most convenient techniques for reliability analysis. Various probability distributions are evaluated for determining the suitable probability distribution of the failure data of the transfer gearbox, and the resulting correlation coefficient indicates that failure data have a lognormal distribution. The expected number of unscheduled maintenance actions and the optimum replacement interval for various values of cost ratios are determined.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.255-264
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• 2012

This paper analyzes the survival rate of small & medium size-cultural contents industry, which includes printing, broadcasting, advertising, entertainment, other manufactures, and so on, by using survival analysis. In this article, after testing significance among characteristic factors and survival rate and hazard rate were estimated The results of the analysis are as follows: There are some significants differences among industries in details. Also there are some significants differences by region, by the number of employees, by financial status, and working periods of CEOs. The contribution of this study is to apply the method of survival analysis to the cultural contents industry in Korea.

• The Journal of the Korea Contents Association
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• v.15 no.5
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• pp.488-497
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• 2015

The recent increase of chonsei has raised the degree of lease burden of households, and a new residential lease price index needs to be introduced to measure such degree of lease burden. In order to convert the burden into an index, the calculation method of the K-HAI, which is announced by the Korea Housing Financing Corporation, is applied by replacing house purchase with lease. From the calculation, the residential lease prices index of the first quarter of 2014 is estimated to be approximately 114, indicating that the cost of lease exceeds 35% of income. The result of analysis on the trend of the residential lease prices index from the first quarter of 2012 to the present in Seoul indicates that the residential lease prices index in Seoul has continued to increase, compared to that of the entire country. The results of this study will be a foundation to find a solution for the stabilization of chonsei and investigate the degree of lease burden by region when establishing a sustainable housing policy.

• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.957-968
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• 2021

Inverse censoring probability weighting (ICPW) is a popular technique in survival data analysis. In applications of the ICPW technique such as the censored regression, it is crucial to accurately estimate the censoring probability. A simulation study is undertaken in this article to see how censoring probability estimate influences model performance in censored regression using the ICPW scheme. We compare three censoring probability estimators, including Kaplan-Meier (KM) estimator, Cox proportional hazard model estimator, and local KM estimator. For the local KM estimator, we propose to reduce the predictor dimension to avoid the curse of dimensionality and consider two popular dimension reduction tools: principal component analysis and sliced inverse regression. Finally, we found that the Cox proportional hazard model estimator shows the best performance as a censoring probability estimator in both mean and median censored regressions.

• Journal of Korean Orthopaedic Sports Medicine
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• v.9 no.2
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• pp.98-103
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• 2010

Purpose: We reported the results of arthroscopically assisted lateral release and medial imbrication for the recurrent patella dislocation. Materials and Methods: Twenty patients (20 knees) underwent arthroscopically assisted surgery for the recurrent patella dislocation. There were 4 males and 16 female. The average age was 20.2 years. All patients had definite trauma history and average follow-up period was 19 months. The surgical results were evaluated according to the Lysholm knee score and the Kujala score. The congruence angle and lateral patellofemoral angle were measured on plain radiograph and the tibial tubercle-trochlear groove distance was calculated on computerized tomography. Results: The median value of preoperative congruence angle was $16.5^{\circ}$ (range, $0.0{\sim}+34^{\circ}$) and the average final follow-up was $-6.4^{\circ}$ (range, $-19{\sim}10^{\circ}$) with statistically significant improvement (p=0.025). The median value of preoperative Lysholm knee score was 70 (range, 63~81) and the final follow-up score had changed to 88 (range, 80~95) with statistically significant improvement (p=0.0341). The median value of preoperative Kujala score was 72 (range, 65~80) and the average final follow-up score showed 87 (range, 80~92) with statistically significant improvement (p=0.024). Recurrent dislocations after surgery occurred in 2 cases, one case which showed positive "thumb to forearm test" had been treated with medial patellofemoral ligament reconstruction. Conclusion: Arthroscopically assisted lateral release and medial imbrication for recurrent patella dislocation without bony malaligmenent showed the effective treatment, but would be inappropriate for the patients with the generalized joint laxity.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.145-155
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• 2022

Koreoleptoxis nodifila (Martens, 1886) is an endangered species only living in the central and north streams of South Korea. However, there is a lack of information on physical habitat characteristics of K. nodifila. We aimed to determine preference ranges for water depth, current velocity, streambed substrate of K. nodifila. The weibull model was used to estimate the habitat suitability based on distribution of individual abundance by physical factors. Optimal depth preferences ranged from 0.53~17.17 cm, current preferences ranged from 48.40~81.03 cm s^-1 and substrate (𝜱_m) preferences ranged from -4.36~ -2.26. Median values of central tendency were determined as follows: water depth 16.73 cm, current velocity 65.23 cm s^-1, substrate -3.51. Mean values of central tendency were determined as follows: water depth 21.32 cm, current velocity 65.65 cm s^-1, substrate -3.63. Mode values of central tendency were determined as follows: water depth 5.17 cm, current velocity 64.77 cm s^-1, substrate -3.24. Based on the habitat suitability analysis, the microhabitat types of K. nodifila were determined as riffle and coarse-grained streambed.

• 한국정보교육학회:학술대회논문집
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• 2005.08a
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• pp.13-20
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• 2005

본 논문에서는 on-line을 통한 교육방법의 하나인 e-learning(Web Based Instruction)을 활용한 음악과 수업모형을 개발하여 교육적 활용 효과를 검증하였다. 웹 기반 교수학습 자료를 구축하고 각종 학습 자료를 탑재하여 수업에 활용하였으며, 교육 효과를 보다 정확히 알아보기 위해 수준별(상,중,하) 3개 그룹으로 나누어 e-learning 기법을 적용 사전평가 및 사후평가를 통하여 얻어진 결과를 통계 처리하여 검증하였다. 본 논문에서는 학습자의 능력과 필요에 따라 능동적인 학습이 이루어지도록 하였다. 개별학습, 반복학습 및 자기주도적 학습을 진행할 수 있도록 구성하였으며, 그 결과 구체적이고 실질적인 학습 효과를 얻을 수 있었다. e-learning 활용수업을 실시한 실험 집단 전체에서 off-line 수업을 실시한 통제집단보다 학습 성취도에 있어서 효과적인 것을 확인할 수 있었다. 상위, 중위 그룹의 학생들에게는 웹 기반 교수학습 활용수업이 학습효과에 있어서 큰 차이가 없었지만 하위 그룹의 학생들에게는 크게 효과적인 것으로 나타났다.

• Communications of Mathematical Education
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• v.8
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• pp.121-135
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• 1999

본 연구는 초등학교 수학의 연산 영역에 있어서, 문제설정활동의 두 가지 방법(문제꾸미기, 문제만들기) 중 어느 방법이 4학년 아동의 수학적 문제해결력에 더 효과적인지 알아보고, 아동의 학습능력수준과 성별에 따라 수학적 문제해결력의 신장에 더 유용한 문제설정방법을 찾아보는데 그 목적이 있었다. 그 결과 '문제꾸미기'에 의한 문제설정방법이 학습 수준이 상 ${\cdot}$중위 집단에서 유용한 방법이며, 문제해결력 요소 중 문제구성력과 전략적용력을 신장시킬 수 있다는 방법이라는 것을 알 수 있었고 남녀성별에 따른 유의미한 차이는 없었다. 이런 연구 결과로 주어진 문제를 조건과 내용을 바꾸는 다소 쉬운 문제설정 방법보다는 어떤 상황만 제시하고 그 상황 속에서 문제를 만들어보는 문제꾸미기의 문제설정 방법이 문제해결력의 신장에 도움이 됨을 알 수 있었다.

• Management & Information Systems Review
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• v.34 no.4
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• pp.15-29
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• 2015

This study aims to empirically analyze the relationship between management ownership and corporate performance and stock returns indicates the ownership structure of the company to target the listed companies in China over the past five years from 2010 to 2014. The empirical results are as follows: Management ownership gave an impact on stock returns, especially high-stakes management ownership showed significant positive effect with the stock returns. But management ownership don't have significant positive effect with ROA. The contribution of this study is as follows. Chinese companies have the efficiency of the management through the separation of ownership and management in accordance with the changes realized in capitalism. And this study is reflecting the fact of China using the Chinese data. This study has limitations of that. Management ownership measurement of governance structure don't expand the range, and measurement of governance structure is just one. The following studies are expected to be more sophisticated by comparison of countries.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.270-277
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• 2014

This research analyzed job satisfaction for improvement in job satisfaction of forest interpreters and effective management. Interpreters felt satisfied with their job with a mean satisfaction score 3.41 out of 5 but unsatisfied with pay and job benefits. Job satisfaction showed significant differences in interpreting field, agencies and working period. Results from factor analysis, job satisfaction classified into four factors; team atmosphere, level of compensation, job conflict and working environment. And interpreters more satisfied in team atmosphere and working condition than level of compensation and job conflict. Also this study showed related variables to job satisfaction. Team atmosphere was related with working period and agency, the level of compensation was also related with agency and the working environment is in relation to agency and interpreting field.