• Journal of Communications and Networks
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• 제11권3호
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• pp.240-247
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• 2009

The results of performance analysis by adopting the channel scenarios characterized as Weibull fading for an multicarrierdirect sequence-coded division multiple access (MC-DS-CDMA) system are proposed in this investigation. On the other hand, an approximate simple expression with the criterion of bit error rate (BER) versus signal-to-noise ratio (SNR) method is derived for an MC-DS-CDMA system combining with maximal ratio combining (MRC) diversity based on the moment generating function (MGF) formula of Weibull statistics, and it associates with an alternative expression of Gaussian Q-function. Besides, the other point of view on the BER performance evaluation of an MC-DS-CDMA system is not only the assumption of both single-user and multi-user cases applied, but the phenomena of partial band interference (PBI) is also included. Moreover, in order to validate the accuracy in the derived formulas, some of the system parameters, such as Weibull fading parameter (${\beta}$), user number (K), spreading chip number (N), branch number (L), and the PBI (JSR) values, etc., are compared with each other in the numerical results. To the best of author's knowledge, it is a brand new idea which proposes the evaluation of the system performance for an MC-DS-CDMA system over the point of view with Weibull fading channel.

• 한국치위생학회지
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• 제19권6호
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• pp.1037-1046
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• 2019

Objectives: This study was conducted to test the critical thinking tendency, clinical practice satisfaction, and clinical performance, and analyze the factors impacting clinical practice satisfaction and clinical performance of dental hygiene students. Methods: The study conducted a written survey during the period between 30 July ~20 August 2019, among 3rd and 4th year dental hygiene students from Seoul, Gyung-gi region, who had taken clinical practice courses. Using SPSS 22.0 program (IBM SPSS statistics, New York, USA), the study analyzed the final 174 cases. Results: Dental hygiene students scored 3.33±0.43, 3.48±0.83, and 3.30±0.58 for critical thinking, clinical practice satisfaction, and clinical performance, respectively. The clinical thinking score was higher when their study performance was good (p<0.001), clinical practice satisfaction was higher when their major satisfaction was satisfactory (p<0.001), higher when their relationship with their clinical practice partner was good, and the clinical performance was better when the students' major satisfaction was good (p<0.001). The study performance yielded better results when their study achievement was better (p<0.05). Clinical practice satisfaction (r=0.156) and clinical performance (r=0.393) showed a positive correlation with critical thinking, and clinical performance had a positive correlation with clinical practice satisfaction. The impact factor for clinical practice satisfaction appeared to be clinical performance (p<0.05) and major satisfaction (p<0.001), and the factors impacting the clinical performance were among the sub-causes of critical thinking (p<0.05), intellectual fairness (p<0.05), watchfulness (p<0.05), clinical practice satisfaction (p<0.05), and major satisfaction (p<0.01). Conclusions: Results of the study showed that for dental hygiene students, critical thinking, clinical practice satisfaction, clinical performance, and major satisfaction were the impact factors affecting the students' clinical performance. Therefore, the study recommends that development of educational programs and operation of a field-based curriculum is necessary to improve critical thinking, clinical practice satisfaction, and major satisfaction.

• 대한기계학회논문집A
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• 제32권8호
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• pp.693-700
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• 2008

The primary mirror system in a satellite camera is an opto-mechanically coupled system for a reason that optical and mechanical behaviors are intricately interactive. In order to enhance the opto-mechanical performance of the primary mirror system, opto-mechanical behaviors should be thoroughly investigated by using various analysis procedures such as elastic, thermo-elastic, optical and eigenvalue analysis. In this paper, optimal design of the bipod flexure mounts for high opto-mechanical performance is performed. Optomechanical performances considered in this paper are RMS wavefront error under the gravity and thermal loading conditions and 1st natural frequency of the mirror system. The procedures of the flexure mounts design based on design of experiments and statistics is as follows. The experiments for opto-mechanical analysis are constructed based on the tables of orthogonal arrays and analysis of each experiment is carried out. In order to deal with the multiple opto-mechanical properties, MADM (Multiple-attribute decision making) is employed. From the analysis results, the critical design variables of the flexure mounts which have dominant influences on opto-mechanical performance are determined through analysis of variance and F-test. The regression model in terms of the critical design variables is constructed based on the response surfaceanalysis. Then the critical design variables are optimized from the regression model by using SQP algorithm. Opto-mechanical performance of the optimal bipod flexure mounts is verified through analysis.

• 응용통계연구
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• 제32권4호
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• pp.607-618
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• 2019

현대 과학기술의 발전으로 인해 함수 형태의 자료(functional data)는 기상학, 생물의학과 다양한 분야에서 발생하고 있으며 이러한 자료를 분석하는 것은 새롭고 흥미로운 통계과제라 할 수 있다. 스칼라 반응변수를 가진 함수형 선형회귀 모형(functional linear regression models with scalar response)은 널리 사용되는 함수형 자료 분석기법 중의 하나라 할 수 있고 이 회귀 모형에서 함수형 자료 (설명변수) 가 스칼라 반응변수에 영향력을 미치는지 검정하는 것은 중요한 문제라 할 수 있다. 최근, Kong 등은 함수형 주성분분석(functional principle component analysis)에 의한 차원 축소, 즉, 함수형 주성분분석 결과 얻어지는 고유함수(eigenfunctions)를 활용한 검정방법을 제안했다. 하지만, 그 고유함수들은 검정문제에서 관심사인 함수형 설명변수와 스칼라 반응변수의 연관성이 아니라 함수형 설명변수의 변동만을 고려하기 때문에 회귀문제에 사용하기에 일반적으로 적합한 기저가 아니다. 게다가, 자료로부터 추정하여야 하기 때문에 이 불필요한 추정오차가 검정 절차 성능에 포함될 가능성이 있다. 이러한 단점을 피하기 위해 본 논문에서는 기존의 고유기저함수가 아닌 고정기저(fixed basis)인 B-스플라인(B-splines) 함수를 활용한 검정 방법을 제안한고 모의실험을 통해 검정방법이 잘 작동한다는 것을 보여준다. 또한, 제안한 검정 방법은 B-스플라인의 국소화 성질 때문에 때론 효율적이고 직관적인 결과를 제공하는데 이를 모의실험과 실증자료 분석을 통해 보여줄 것이다.

• Korean Journal of Radiology
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• 제24권8호
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• pp.772-783
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• 2023

Objective: Imaging-based survival stratification of patients with gliomas is important for their management, and the 2021 WHO classification system must be clinically tested. The aim of this study was to compare integrative imaging- and pathology-based methods for survival stratification of patients with diffuse glioma. Materials and Methods: This study included diffuse glioma cases from The Cancer Genome Atlas (training set: 141 patients) and Asan Medical Center (validation set: 131 patients). Two neuroradiologists analyzed presurgical CT and MRI to assign gliomas to five imaging-based risk subgroups (1 to 5) according to well-known imaging phenotypes (e.g., T2/FLAIR mismatch) and recategorized them into three imaging-based risk groups, according to the 2021 WHO classification: group 1 (corresponding to risk subgroup 1, indicating oligodendroglioma, isocitrate dehydrogenase [IDH]-mutant, and 1p19q-codeleted), group 2 (risk subgroups 2 and 3, indicating astrocytoma, IDH-mutant), and group 3 (risk subgroups 4 and 5, indicating glioblastoma, IDHwt). The progression-free survival (PFS) and overall survival (OS) were estimated for each imaging risk group, subgroup, and pathological diagnosis. Time-dependent area-under-the receiver operating characteristic analysis (AUC) was used to compare the performance between imaging-based and pathology-based survival model. Results: Both OS and PFS were stratified according to the five imaging-based risk subgroups (P < 0.001) and three imaging-based risk groups (P < 0.001). The three imaging-based groups showed high performance in predicting PFS at one-year (AUC, 0.787) and five-years (AUC, 0.823), which was similar to that of the pathology-based prediction of PFS (AUC of 0.785 and 0.837). Combined with clinical predictors, the performance of the imaging-based survival model for 1- and 3-year PFS (AUC 0.813 and 0.921) was similar to that of the pathology-based survival model (AUC 0.839 and 0.889). Conclusion: Imaging-based survival stratification according to the 2021 WHO classification demonstrated a performance similar to that of pathology-based survival stratification, especially in predicting PFS.

• 한국콘텐츠학회논문지
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• 제17권11호
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• pp.461-469
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• 2017

본 연구는 장애인거주시설 종사자의 인권의 중요도 인식과 현재 실행도와의 차이를 비교하여 향후 시설에서 해결되어 할 인권문제의 기초자료를 도출하는데 그 목적이 있다. 이를 부산지역 장애인거주시설 종사자 539명을 대상으로 장애인거주시설 인권의 인식 수준과 실행수준은 어느 정도인지, 중요도 인식과 현재 실행도 간의 차이가 존재하는지에 대한 연구를 수행하였다. 연구결과 첫째, 장애인거주시설 종사자의 인권 실천의 중요도와 실행도의 기술통계 결과, 중요도(전체 평균 6.27)에 비해 실행도(전체 평균 6.07)가 낮게 나타났다. 둘째, 장애인 인권 실천 항목들에 대해서 장애인거주시설 종사자가 인식하고 있는 중요도와 실제 실천 정도는 차이를 보였다. 셋째, 인권 실천 하위영역별로 보았을 때 정치권/법 절차적 권리를 제외하고 자유권, 생존권, 사회권의 중요도와 실행도의 평균차이는 통계적으로 유의미하게 나타났다. 이러한 결과를 바탕으로 실천적 함의와 향후 과제를 제언하였다.

• 응용통계연구
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• 제21권5호
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• pp.775-781
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• 2008

본 연구의 목적은 생명보험회사의 경쟁력을 강화시키기 위한 요인을 분석하는데 있다. 기존의 연구와 달리 단일 성과변수가 아닌 생명보험회사의 경영 활동을 언더라이팅 활동과 투자 활동으로 나누고 각 활동에서 비용 성과와 이익성과로 나누어 각 성과에 영향을 미치는 기업 특성변수를 분석함으로써 생명보험회사의 경쟁력 강화 방안을 제시하고 있다. 연구결과 첫째, 언더라이팅 활동에서의 비용 성과와 다근 성과변수간에는 유의한 상관관계가 있으나, 나머지 세 성과변수인 투자 활동에서의 비용 성과, 투자 활동에서의 이익 성과, 언더라이팅 활동에서의 이익 성과간에는 모두 상관관계가 유의하지 못한 것으로 분석되었다. 둘째, 생명보험회사가 비용 측면에서 경쟁력을 강화하기 위해서는 보장성보험의 비중을 높여야 하는 것으로 분석되었다. 마지막으로 투자 측면에서는 대출채권의 비율을 증대시켜야 경쟁력을 강화시킬 수 있는 것으로 나타났다.

• 한국콘텐츠학회논문지
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• 제20권6호
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• pp.1-8
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• 2020

빅데이터 분석에서 텍스트 데이터의 활용이 증가하고 있다. 따라서 텍스트 데이터의 분석 기법에 관한 많은 연구가 이루어지고 있다. 본 논문에서는 텍스트 데이터로부터 추출된 키워드 데이터의 분석을 위하여 공액사전분포 기반의 베이지안 학습 방법이 연구된다. 베이지안 통계학은 기존의 데이터에 새로운 데이터가 추가될 때마다 모수를 갱신하는 데이터 학습을 제공하기 때문에 시간에 따라 대용량의 데이터가 생성 및 추가되는 빅데이터 환경에서 효율적인 방법을 제공한다. 제안 방법의 성능과 적용 가능성을 보이기 위하여 실제 특허 빅데이터를 전처리하여 구축된 정형화된 키워드 데이터를 분석하는 사례연구를 수행한다.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2002년도 11월 학술대회지
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• pp.81-85
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• 2002

We present a statistical analysis of Korean phonological variations using automatic generation of phonetic transcription. We have constructed the automatic generation system of Korean pronunciation variants by applying rules modeling obligatory and optional phonemic changes and allophonic changes. These rules are derived from knowledge-based morphophonological analysis and government standard pronunciation rules. This system is optimized for continuous speech recognition by generating phonetic transcriptions for training and constructing a pronunciation dictionary for recognition. In this paper, we describe Korean phonological variations by analyzing the statistics of phonemic change rule applications for the 60,000 sentences in the Samsung PBS(Phonetic Balanced Sentence) Speech DB. Our results show that the most frequently happening obligatory phonemic variations are in the order of liaison, tensification, aspirationalization, and nasalization of obstruent, and that the most frequently happening optional phonemic variations are in the order of initial consonant h-deletion, insertion of final consonant with the same place of articulation as the next consonants, and deletion of final consonant with the same place of articulation as the next consonants. These statistics can be used for improving the performance of speech recognition systems.

• Journal of the Korean Data and Information Science Society
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• 제8권2호
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• pp.183-194
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• 1997

이 논문의 목적은 제2종 중도절단자료된 가속수명 자료가 형상모수를 고정시킨 와이블분포를 한다는 가정에서 데이터에 대한 경험적베이즈 방법을 이용하여 분석하는데 있다. 이 논문에서는 적률추정법과 최우추정법을 이용한 경험적 베이지안 방법을 제안하고, Pathak등에 의해 제안된 경험적베이지안 방법과 비교한다. 특히, 인위적 자료를 이용한 모의 실험을 통하여 추정량들을 추정된 베이즈위험측면에서 비교한다.