• Nutrition Research and Practice
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• 제17권4호
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• pp.789-802
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• 2023

BACKGROUND/OBJECTIVES: Habitual coffee consumption was inversely associated with type 2 diabetes (T2D) and hyperglycemia in observational studies, but the causality of the association remains uncertain. This study tested a causal association of genetically predicted coffee consumption with T2D using the Mendelian randomization (MR) method. SUBJECTS/METHODS: We used five single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs) associated with habitual coffee consumption in a previous genome-wide association study among Koreans. We analyzed the associations between IVs and T2D, fasting blood glucose (FBG), 2h-postprandial glucose (2h-PG), and glycated haemoglobin (HbA1C) levels. The MR results were further evaluated by standard sensitivity tests for possible pleiotropism. RESULTS: MR analysis revealed that increased genetically predicted coffee consumption was associated with a reduced prevalence of T2D; ORs per one-unit increment of log-transformed cup per day of coffee consumption ranged from 0.75 (0.62-0.90) for the weighted mode-based method to 0.79 (0.62-0.99) for Wald ratio estimator. We also used the inverse-variance-weighted method, weighted median-based method, MR-Egger method, and MR-PRESSO method. Similarly, genetically predicted coffee consumption was inversely associated with FBG and 2h-PG levels but not with HbA1c. Sensitivity measures gave similar results without evidence of pleiotropy. CONCLUSIONS: A genetic predisposition to habitual coffee consumption was inversely associated with T2D prevalence and lower levels of FBG and 2h-PG profiles. Our study warrants further exploration.

• 한국콘텐츠학회논문지
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• 제20권1호
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• pp.356-363
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• 2020

사물인터넷 시대가 되면서 다양한 디바이스가 유·무선으로 연결되고 있다. 이에 따른 일상생활의 편리성 향상과 함께 사생활 침해, 정보유출, 서비스 거부 등의 보안 문제가 증가하고 있다. 공개키 암호 시스템의 하나인 타원곡선 암호 시스템 ECC는 사용하는 키의 크기가 RSA 알고리즘보다 상대적으로 작아 제약적인 환경의 디바이스에 널리 사용되고 있다. 그러나 제약적인 환경의 디바이스에 적용된 ECC의 비밀 키는 스칼라 곱셈 연산을 수행하는 과정에서 전력 분석 공격법에 의해 노출될 수 있다. 본 논문에서는 SECG 표준 타원곡선 파라미터의 스칼라 곱셈 방법에 대해 차분 전력 분석에 대응하고 연산의 효율성을 증가시키는 방법을 알아본다. 제안하는 방법은 비밀 키에 타원곡선 위수의 난수 배를 더하여 차분 전력 분석에 대응하는 Coron의 방법을 사용한다. 연산의 효율성을 증가시키기 위해 SECG 표준 파라미터의 위수 n을 상대적으로 작은 상수 c로 n=2^l±c로 표현하고, 2^lP =∓cP인 성질을 이용한다. 임의의 난수를 사용한 Coron의 키-난수화 방법은 스칼라 곱셈 수행을 2l번 하는데, 본 논문에서 제안하는 방법은 위수 성질을 이용하면 스칼라 곱셈 수행을 약 (3/2)l번 수행하게 되어 25% 정도 연산의 효율성이 향상된다.

• 전력전자학회논문지
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• 제6권6호
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• pp.525-537
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• 2001

본 연구에서는 펄스의 위치를 랜덤하게 함으로써 효율적은 RPWN (Random PWM)을 구현할 수 있는 새로운 공간 벡터 RPPWM(Random Position PWM)방식을 제안하였다. 제안한 방식은 마이크로 컨트롤로 적용하기 쉬운 공간벡터 변조에 의하여 각 상의 듀티비를 연산한 다음, 스위칭 순서를 유지하며 각 3상 펄스들의 위치를 변조구간내에서 임의의 위치에 랜덤하게 배치함으로써 RPWM을 구현하는 방식이다. 제안된 방법의 타당성을 검증하기 위하여 MATLAB/SIMULINK를 이용하여 펄스위치의 랜덤화 공각벡터 변조, 인버터 및 3상 유도전동기를 포함하는 전체 시스템을 모델화하였다. 종전의 공각벡턱 PWM 그리고 제안된 RPPWM에 의한 인버터 출력 전압 전류의 고조파 성분을 시뮬레이션에 의하여 비교 검토하였으며 제안된 방법의 유용성을 입증할 수 있었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권7호
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• pp.387-398
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• 2002

In this paper, a new Three-Phase Lead-Lag Random Pulse Position PWM(LL-RPWM) scheme is proposed and implemented for decreasing audible acoustic noise of motor drives. In the proposed RPWM(Random PWM), each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the randomization of the PWM pulses, we can obtain the effects of spread spectra of voltage, current as in the case of randomly changed switching frequency. To verify the validity of the proposed LL-RPWM, the simulation and experimental study was tried. Along with the randomization PWM pulses, the space vector modulation is also executed in the C167 micro-controller. The simulation and experimental results show that the voltage and current harmonics are spread to a wide band area and that the audible acoustic noise is reduced by the proposed RPWM method.

• 대한한의학회지
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• 제30권5호
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• pp.115-126
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• 2009

Objective: By assessing the quality of methodology and synthesis of results of RCTs (Randomized Controlled Clinical Trials) with herbal acupuncture (pharmacopuncture), we hope to help with administrating herbal acupuncture therapy in clinic and conducting RCT with herbal acupuncture. Methods: Reports of RCT conducted in Korea published in medical journals until February 2009 were collected. We surveyed elementary information of RCTs, evaluated randomization, double-blinding, allocation concealment and put together the results of RCTs by seven clinical topics. Results: 38 RCTs with herbal acupuncture were selected, then adequate methods for randomization and allocation concealment were found in 39% and 5% of studies. Complete double-blinding and a clear accounting of all participants were conducted in 42% and 50% of reports. The synthesis of RCTs revealed that herbal acupuncture was useful and effective on degenerative gonarthritis, omarthralgia on cerebrovascular accident, acute ankle sprain, back sprain, neck sprain, headache, rheumatoid arthritis and tennis elbow, generally. Conclusions: Although further improvement in quality of methodology of RCTs with herbal acupuncture is required, clinical usefulness of herbal acupuncture was shown especially on disorders of musculoskeletal system via RCTs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.106-111
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• 2002

In this paper, a new three phase RPWM(Random PWM)with fixed switching frequency is proposed. In the proposed RPWM, each of three phase pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the the randomization of the PWM pulses, we can obtain the effects of spread spectra of voltage, current as in the case of randomly changed switching frequency. To verify the validity of the proposed RPWM, the experimental study was tried. Along with the randomization of PWM pulses, the space vector modulation is also executed in the C167 micro-controller. The experimental results show that the voltage and current harmonics are spread to a wide band area and that the audible acoustic noise is reduced by the proposed RPWM method.

• 대한한의학회지
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• 제31권5호
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• pp.12-32
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• 2010

Objective: This study aimed to review herbal remedy-based RCTs on cancer patients in order to produce helpful information for clinical study of herbal medicine in the future. Methods: We collected all RCTs using herbal remedies on cancer patients from Pubmed and Cochrane databases until November 1st, 2009. Elementary information such as nation where performed, clinical question, design, randomization, double-blinding and allocation concealment were analyzed. Results: 153 RCTs were finally selected. 119 RCTs were conduced in China while only 2 were done in Korea. The most frequent targeted cancer was lung cancer as 29 RCTs. The main clinical questions included improvement of quality of life, elongation of survival rate and regression of tumor being 83, 62 and 55 respectively. 112 RCTs used herbal remedies with western therapy. Adequate methods for randomization and allocation concealment were found in 37% and 10% of trials respectively. Conclusions: We found that herbal remedies are used on cancer patients in aspects of both caring for the human body and tumor treatment itself. The study might provide us useful data for cancer-related clinical study using herbal remedies in the future.

• Communications for Statistical Applications and Methods
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• 제28권5호
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• pp.411-424
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• 2021

Inference following two-stage adaptive designs (also known as two-stage randomization designs) with survival endpoints usually focuses on estimating and comparing survival distributions for the different treatment strategies. The aim is to identify the treatment strategy(ies) that leads to better survival of the patients. The objectives of this study were to assess the performance three commonly cited methods for estimating survival distributions in two-stage randomization designs. We review three non-parametric methods for estimating survival distributions in two-stage adaptive designs and compare their performance using simulation studies. The simulation studies show that the method based on the marginal mean model is badly affected by high censoring rates and response rate. The other two methods which are natural extensions of the Nelson-Aalen estimator and the Kaplan-Meier estimator have similar performance. These two methods yield survival estimates which have less bias and more precise than the marginal mean model even in cases of small sample sizes. The weighted versions of the Nelson-Aalen and the Kaplan-Meier estimators are less affected by high censoring rates and low response rates. The bias of the method based on the marginal mean model increases rapidly with increase in censoring rate compared to the other two methods. We apply the three methods to a leukemia clinical trial dataset and also compare the results.

• Journal of Acupuncture Research
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• 제29권5호
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• pp.109-118
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• 2012

Objectives : The aim of this study was to evaluate the effectiveness and safety of acupuncture for chronic fatigue syndrome and idiopathic chronic fatigue. Methods : A randomized, controlled pilot trial was conducted. Twenty-four participants were randomized into one of the two groups: an acupuncture group(n=12) and wait-list group(n=12). The treatment group received 12 sessions of acupuncture over 4 weeks. Eight points($GV_{20}$; bilateral GB20, $BL_{11}$, $BL_{13}$, $BL_{15}$, $BL_{18}$, $BL_{20}$, and $BL_{23}$) were selected for needling. The control group did not receive acupuncture treatment during study period and follow-up were done in the $5^{th}$ and $9^{th}$ weeks after randomization in both groups. The primary outcome was fatigue severity scale(FSS) and the secondary outcomes included a short form of stress response inventory(SRI-short form), beck depression inventory(BDI), and insomnia severity index(ISI). Safety was assessed at every visit. Results : There were statistically significant differences in the between group values of FSS at $5^{th}$ weeks after randomization(p=0.0002), SRI-short form, BDI, and ISI at $5^{th}$, $9^{th}$ weeks after randomization(p<0.01). There were no adverse events. Conclusions : The results suggest that acupuncture is associated with benefits on the short-term outcomes in chronic fatigue syndrome and idiopathic chronic fatigue.

• 한국수학교육학회지시리즈A:수학교육
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• 제38권2호
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• pp.165-172
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• 1999

$\sub$e/$\^$2/, that were results from those three sources of such imperfection. Especially to eliminate the differences in severity among many raters the randomization procedure of raters sample was very effective in enhancing the reliability of ratings with comparatively small groups of examinees and raters. And we also introduced the new rating methods, i.e. the 2-step diagnostic procedures to check the sizes of the reliability stability of raters and the sore adjustment method to enumerate the optimal mean values in rating the examinees.