• Journal of Korean Society of Disaster and Security
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• v.13 no.2
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• pp.65-75
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• 2020

The efficiency of sewage treatment was ananlyzed selecting a sewage treatment plant in Gyeonggi-do where A₂O process was applied. Statistical techniques based on the operation data of the sewage treatment were used. The main factors directly affecting the efficiency of the treatment process were analyzed using a GPS-X model. The correlation analysis and one-way ANOVA were performed. The T-N and NH₄⁺-N values of the effluent did not generate statistically significant level (p-value:>0.05) when compared with C/N ration values. Removel of nitrogen components form sewage treatment plants were affected by temperature, HRT, SRT and DO. In the case of BOD, all operating factors were affected, while COD was affecte by factors of HRT, STR and DO. In simulations using GPS-X, the parameters that greatly influence was included the maximum sedimentation rate, the dependent nutrient microbial yield (anoxic), the phosphorus saturation coefficient, the dependent nutrient microbial killing rate, the dependent nutrient microbial maximum growth rate, and the independent trophic microorganisms. The maximum growth rate and the maximum setting rate were identified.

• The Korean Journal of Applied Statistics
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• v.33 no.3
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• pp.335-345
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• 2020

This paper deals with the problem of estimating the log-transformed linear regression model to fit actual battle data from the Ardennes Campaign of World War II into the Lanchester model. The problem of determining a global solution for parameters and multicollinearity problems are identified and modified by examining the results of previous studies on data. The least squares method requires attention because a local solution can be found rather than a global solution if considering a specific constraint or a limited candidate group. The method of exploring this multicollinearity problem can be confirmed by a statistic known as a variance inflation factor. Therefore, the Lanchester model is simplified to avoid these problems, and the combat power attrition rate model was proposed which is statistically significant and easy to explain. When fitting the model, the dependence problem between the data has occurred due to autocorrelation. Matters that might be underestimated or overestimated were resolved by the Cochrane-Orcutt method as well as guaranteeing independence and normality.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.29-44
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• 2009

A variety of research efforts, using advanced wireless communication technologies, have been made to develop more reliable traffic information system. This study presents a novel decentralized traffic information system based on vehicle infrastructure integration (VII). A major objective of this study was also to devise a methodology for determining appropriate spacing of roadside equipment (RSE) to fully exploit the benefits of the proposed VII-based traffic information system. Evaluation of travel time estimation accuracy was conducted with various RSE spacings and the market penetration rates of equipped vehicle. A microscopic traffic simulator, VISSIM, was used to obtain individual vehicle travel information for the evaluation. In addition, the ANOVA tests were conducted to draw statistically significant results of simulation analyses in determining the RSE spacing. It is expected that the proposed methodology will be a valuable precursor to implementing capability-enhanced next generation traffic information systems under the forthcoming ubiquitous transportation environment.

• Journal of radiological science and technology
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• v.33 no.1
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• pp.11-17
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• 2010

This study was conducted in order to analyze job stress factors of radiotechnologists in order to inprove the work efficiency and to organize system management plans. For data collection, total 261 radiotechnologists, who work in Busan, took part in structured questionnaire survey. The collected data were analyzed by using SPSS/PC+ Win 13 version. For verification of the differences among groups, one-way ANOVA was executed. For analyzing efficiency of system, which is affected by job stress, multiple regression analysis was taken. First, work stress classified by age group was found as the biggest stress factor among radiotechnologists in their 30s. Among radiotechnologists in their 20s, 40s and 50s, the biggest stress factor was communication problems. In terms of, job stress classified by division, no statistical difference was observed among groups. Second, as the result of system efficiency analysis, high values were found in organizational immersion and job satisfaction among radiotechnologists in their 20s and oncology division has the highest values in concentrating the system and job satisfaction. For this result, statistically significant differences were observed among groups. Third, in terms of the sub-factors of work stress, communication problem was found as the variable that exerted statistically significant impact to organizational effectiveness. However, no statistically significant differences were observed inadministrative and personal problems. Job stress decreases as communication within the organizations or communication with other divisions becomes more successful. In other words, system efficiency can be enhanced by decreasing conflicts within organization through successful communication.

• The Korean Journal of Applied Statistics
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• v.33 no.5
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• pp.527-540
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• 2020

While analyzing data, researching outliers, which are out of the main tendency, is as important as researching data that follow the general tendency. In this study we discuss the influence function for outlier discrimination. We derive sample influence functions of sample mean, sample variance, and sample standard deviation, which were not directly derived in previous research. The results enable us to mathematically examine the relationship between the empirical influence function and sample influence function. We can also consider a method to approximate the sample influence function by the empirical influence function. Also, the validity of the relationship between the approximated sample influence function and the empirical influence function is also verified by the simulation of random sampled data in normal distribution. As the result of a simulation, both the relationship between the two influence functions, sample and empirical, and the method of approximating the sample influence function through the emperical influence function were verified. This research has significance in proposing a method that reduces errors in the approximation of the empirical influence function and in proposing an effective and practical method that proceeds from previous research that approximates the sample influence function directly through empirical influence function by constant revision.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1205-1208
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• 2010

본 연구는 초등학교 5, 6학년 학생의 인터넷 중독과 학교생활 적응과의 관계를 파악하여 인터넷 사용에 대한 교육적 지도방안과 인터넷 중독 예방프로그램 개발의 기초 자료를 제공하고자 시도되었다. 자료는 2009년 7월 1일에서 7월 24일까지 제주특별자치도에 위치한 초등학교 6개교(동지역 4개교, 읍지역 2개교)를 무작위 추출하여 5, 6학년 학생 총 1195명을 대상으로 조사하였다. 자료 분석은 SPSSWIN(12.0 한글판) 프로그램을 이용하여 카이제곱검정, t-검정, 일원배치 분산분석, 상관분석, 다중회귀분석의 통계적 방법을 이용하였다. 본 연구의 주요 결과는 첫째, 대상자의 인터넷 중독 정도는 고위험군 55명(5.5%), 잠재적위험군 49명 (4.9%), 정상군 900명(89.6%)으로 나타났으며, 둘째, 대상자의 일반적 특성에 따른 인터넷 중독 정도를 분석한 결과 성별, 형제자매 유무, 학교성적에 따라 유의한 차이가 있었다. 셋째, 대상자의 컴퓨터 사용 특성에 따른 인터넷 중독 정도는 최초 인터넷 이용 시기, 인터넷 이용용도, 하루 인터넷 사용 시간, 부모컴퓨터 사용 여부에 따라 유의한 차이가 있었으며, 넷째, 인터넷 중독과 학교생활 적응과의 관계를 분석한 결과 학교생활 부적응인 경우는 '고위험군' 32명(58.2%), '잠재적위험군' 24명(50.0%), '정상군' 257명 (28.7%)으로 고위험군과 잠재적위험군이 정상군보다 학교생활 적응 정도가 낮은 것으로 조사되었다(p<0.01). 다섯째, 인터넷 중독에 유의한 영향을 주는 변수는 학교생활 적응 정도, 성별, 하루 인터넷 사용시간, 인터넷 이용용도, 인터넷 이용 상황, 어머니 직장 유무, 거주 지역, 부모 컴퓨터 사용여부, 최초 인터넷 이용시기이었다. 학교생활 적응 정도가 낮을 때, 남학생, 하루 인터넷 사용시간이 3시간 이상, 인터넷 이용 용도가 '게임', '스트레스가 쌓였을 때' 인터넷을 이용하는 경우, 어머니 직장이 있는 경우, 거주 지역이 동지역, 부모님이 컴퓨터를 사용할 줄 모르는 경우, 최초 인터넷 이용 시기가 취학 전인 경우가 인터넷 중독 점수가 높은 것으로 나타났다. 여섯째, 학교생활 적응에 유의한 영향을 주는 변수는 인터넷 중독 점수, 학교성적, 가정경제수준, 거주지역, 인터넷 이용용도, 학년이었다. 인터넷 중독 점수가 낮을수록, 학교성적이 높을수록, 가정경제수준이 잘 살수록, 거주지역이 동지역, 인터넷 이용용도가 '정보검색, 홈페이지관리/메신저', 5학년인 경우에 학교생활 적응을 더 잘하고 있는 것으로 나타났다. 이상의 결과를 종합해 보면, 학교생활 적응 정도가 낮을수록 인터넷 중독 점수가 높게 나타나고 있고, 인터넷 중독 경향이 높을수록 학교생활 적응 수준이 낮게 나타나고 있음을 알 수 있다. 아동들은 하루중 대부분의 시간을 학교에서 생활하고 있기 때문에 학교생활 적응은 아동들이 건전한 성인으로 성장하는데 중요한 요인이 된다. 또한, 인터넷사용률 증가와 최초 인터넷 이용 연령층이 점점 낮아지고 있음에 따라 인터넷 중독률이 자연스럽게 점점 높아질 것으로 예측되어진다. 따라서, 가정과 학교가 연계하여 아동들의 인터넷 사용에 대한 지속적인 관심과 지도가 필요하며, 인터넷 중독경향이 높은 아동들이 학교생활 적응을 잘할 수 있도록 인터넷 중독 치료 및 예방교육 프로그램 운영이 필요하다 하겠다.

• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.114-122
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• 2015

This study aims to analyze the satisfaction of seniors living in Cheonan City downtown as to their residential environment. Also, this study intends to identify which factors should be improved first to make downtown a favorable residential area. To that end, 'social indicators of Chungnam' was used. The collected data was analyzed through a statistical analysis method using ANOVA (analysis of variance) and a cluster analysis. It led to the following findings. First, 6.9% of the elderly residents expressed their wish to move from their downtown residence. Thus, the majority of the residents do not want to move. Second, the satisfaction of the elderly residents in their downtown residence scored 6.09. The score is higher than those of other regions. Thus, it is highly possible to develop downtown into a senior-friendly area. Third, as for satisfaction in downtown residence, it was higher among the following groups: men; those with high school or higher level of education; those earning at least a million won a month; family of one generation. Fourth, satisfaction in the following factors was relatively low: culture and education; interaction with neighbors and trust in them; car accidents. Thus, those factors should be improved for downtown residents. Above all, community-faced facilities should be expanded to increase exchanges with neighbors and trust in them. To attract women dissatisfied with downtown residence. it is imperative to increase daily safety by reducing car accidents and crime.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.41-52
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• 2009

The surface treatment of titanium implant could bring out the biochemical bonding between bone and implant. The purpose of this study was to evaluate the biomechanical bone response of Mg-ion implanted implants with plasma source ion implantation method. Twelve New Zealand white rabbits were included in this study. Each rabbit received one control fixture (blasted with resorbable blasting media, RBM) and three types of Mg ion implanted fixtures in tibiae. The implants were left in place for 6 weeks before the rabbits were sacrificed. Removal torque value and resonance frequency analysis (ISQ) were compared. The repeated measured analysis of variance was used with $P{\leq}0.05$ as level of statistical significance. ISQ was not different among all groups. However, the ISQ was increased after 6 weeks healing. The group had lowest ISQ value showed the greatest increment. Mg-1 implants with 9.4% retained ion dose showed significantly higher removal torque value than that of the other implants. From this results, it is concluded that the Mg-1 implants has stronger bone response than control RBM surface implant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.495-505
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• 2010

In this paper, the effect of Near-Far Problem (NFP) among distributed nodes in OFDMA-based Wireless Mesh Networks (WMNs) is analyzed by investigating statistical characteristics of Time Difference of Arrival (TDoA) and Desired-to-Undesired power Ratio (DUR). In order to overcome the effects of Inter-Symbol Interference (ISI), Inter-Carrier Interference (ICI), and Inter Link Interference (ILI), caused by TDoA in WMNs, we derive effective SINR for each subcarrier, and then, propose the optimal starting point of FFT window which can minimize BER for each subcarrier. In addition, we propose a subcarrier-based Zero Forcing - 2 Dimensional Ordered Successive Interference Cancellation (ZF-2DOSIC) technique for signal detection in WMNs with TDoA. It is verified by simulation that the effective SINR and uncoded BER performances of the proposed signal detection technique for OFDMA-based WMNs are significantly improved, compared with those of conventional technique.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.696-703
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• 2015

This paper is a follow-up research of 'A study on the development of Safety Management Evaluation Index for Shipping Company'. It aims to develop the evaluation items of Safety Management Index(hereafter called as 'SMI') applicable to 'Safety Advantage Point', which is suggested as the sub-index of 'Safety Management Evaluation Index' function in the preceding research and also verify their adequacy. For that purpose, firstly, the 11 evaluation items were developed after collecting the practical opinions from safety management personnels in Korean shipping companies. Secondly, the survey was carried out for the verification of the adequacy of the 11 evaluation items. And lastly, its results was analysed, whether it has statistical meanings of differences in adequacy awareness amongst safety managers grouped depending on business type(coastal, ocean-going) and business capacity(number of owned-operating ships). As a result, there was no relevance between their adequacy awareness and business type of their companies. However, a difference in their adequacy awareness existed depending on their companies' business capacity(small, medium and large sized). In conclusion, when the safety management level of shipping companies is evaluated by SMI, the same indices can be applicable to both coastal and ocean-going shipping companies by a grouping of companies' business capacity.