• 한국정보통신학회논문지
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• 제20권1호
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• pp.22-29
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• 2016

수중환경 하에서 표적을 탐지하고 식별하는 문제는 군사적인 목적은 물론 비군사적 목적으로도 많은 연구가 수행되어 왔다. 수중환경에서의 수중음향 신호가 시간 공간적으로 특성이 변화하며 천해 다중경로 환경을 반영하는 복잡한 특성을 보이는 점으로 인해 능동 표적인식 기술은 매우 어려운 기술로 여겨져 왔다. 본 논문에서는 Fractional 푸리에 변환의 기본 개념과 최적 변환 차수에 대해 설명하고, 이를 이용하여 LFM 신호의 시간-주파수 특성과 스펙트럼 사이의 관계를 분석한다. 그리고 이러한 분석결과를 바탕으로 능동소나 표적 탐지 기법을 제안한다. 제안된 방법의 성능을 검증하기 위해, 기존의 FFT를 이용한 정합필터와 성능을 비교하였다. AUC(Area Under the ROC Curve)의 측면에서 볼 때 제안된 방식이 기존의 방법보다 성능이 우수한 실험결과를 보였다.

• 한국산학기술학회논문지
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• 제21권6호
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• pp.374-382
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• 2020

본 연구에서 저장탄약 신뢰성평가(ASRP: Ammunition Stockpile Reliability Program)의 데이터 특성을 고려하여 입력변수를 줄이는 정규화기법을 제안함으로써 분류성능의 저하 없이 저장탄약 신뢰성분류 인경신경망모델의 학습 속도향상을 목표로 하였다. 탄약의 성능에 대한 기준은 국방규격(KDS: Korea Defense Specification)과 저장탄약 시험절차서(ASTP: Ammunition Stockpile reliability Test Procedure)에 규정되어 있으며, 평가결과 데이터는 이산형과 연속형 데이터가 복합적으로 구성되어 있다. 이러한 저장탄약 신뢰성평가의 데이터 특성을 고려하여 입력변수는 로트 추정 불량률(estimated lot percent nonconforming) 또는 고장률로 정규화 하였다. 또한 입력변수의 unitary hypercube를 유지하기 위하여 최소-최대 정규화를 2차로 수행하는 2단계 정규화 기법을 제안하였다. 제안된 2단계 정규화 기법은 저장탄약 신뢰성평가 데이터를 이용하여 비교한 결과 최소-최대 정규화와 유사하게 AUC(Area Under the ROC Curve)는 0.95 이상이었으며 학습속도는 학습 데이터 수와 은닉 계층의 노드 수에 따라 1.74 ~ 1.99 배 향상되었다.

• 지역사회간호학회지
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• 제22권3호
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• pp.302-314
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• 2011

Purpose: This study aimed to validate instruments to classify the frailty of Korean elderly people in community. Methods: For this study, 632 elders were selected from community-based elderly houses and home visiting registries, and data on frailty were collected using three instruments during November, 2008. The Korean Frail Scale (KFS) was composed of 10 domains with the maximum score of 20. The Edmonton Frail Scale (EFS) had 10 domains with the maximum score of 17. The 25_Japan Frail Scale (25_JFS) was composed of 6 domains with the maximum score of 25. Internal consistency was measured with Cronbach's ${\alpha}$. Sensitivity, specificity and area under the curve (AUC) of ROC were measured to see validity with long.term care insurance grade as a gold standard. Results: The Cronbach's ${\alpha}$ was .72 for KFS, .55 for EFS, and .80 for 25_JFS. Sensitivity, specificity, and AUC were 70.0%, 83.2%, and .83, respectively, at cutting point 10.5 for the KFS, 50.0%, 80.9%, and .66, respectively, at 8.5 for EFS, and 80.0%, 85.9%, and .86, respectively, at 12.5 for 25_JFS. Conclusion: KFS and three JFS showed favorable internal consistency and predictive validity. Further longitudinal studies are recommended to confirm predictive validity.

• 한국정보기술학회논문지
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• 제17권12호
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• pp.21-28
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• 2019

약물 부작용이란 질병의 예방, 진단 또는 치료에 사용된 약물로부터 발생한 유해하고 의도하지 않은 현상이다. 이러한 부작용은 환자를 죽음에 이르게 할 수 있으며, 약물 개발 실패의 주요 원인 중 하나이다, 따라서, 다양한 방법들이 부작용을 알아내기 위하여 시도되었다. 본 연구에서는 시스템스 바이올로지 접근법을 기반으로 기존 연구에서 주로 사용되었던 화학적 구조, 생물학적 정보 이외에도 다양한 표현형 정보를 사용하는 것에 주목하였다. 먼저, 5가지 적응증 데이터베이스, 화학적 구조, 타겟 유전자 정보를 수집하고 개별로 유사도를 계산하였다. 테이블은 하나의 약물-부작용에 대하여 앞서 생성된 유사도를 이용하여 생성되었고 다양한 기계학습 기법이 적용되었다. 결과는 AUC(Area Under the ROC Curve)값을 통해 확인하였다. 본 연구의 유의성은 비교 실험을 통하여 확인하였다.

• Nutrition Research and Practice
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• 제8권4호
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• pp.469-475
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• 2014

BACKGROUND/OBJECTIVE: The goal of the present study was to investigate the effects of moderate caloric restriction on ${\beta}$-cell function and insulin sensitivity in middle-aged obese Korean women. SUBJECTS/METHODS: Fifty-seven obese pre-menopausal Korean women participated in a 12-week calorie restriction program. Data on total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), and fasting serum levels of glucose, insulin, C-peptide, blood pressure, leptin and anthropometrics were collected. A dietary intake assessment was based on three days of food recording. Additionally, ${\beta}$-cell function [homeostasis model assessment of ${\beta}$-cell (HOMA-${\beta}$), insulinogenic index (ISI), C-peptide:glucose ratio, and area under curve insulin/glucose ($AUC_{ins/glu}$)] and insulin sensitivity [homeostasis model assessment for insulin resistance (HOMA-IR), Quantitative insulin-sensitivity check index (QUICKI) and Matsuda index (MI)] were recorded. RESULTS: When calories were reduced by an average of 422 kcal/day for 12 weeks, BMI (-2.7%), body fat mass (-10.2%), and waist circumference (-5%) all decreased significantly (P < 0.05). After calorie restriction, weight, body fat percentage, hip circumference, BP, TC, HDL-C, LDL-C, plasma glucose at fasting, insulin at fasting and 120 min, $AUC_{glu}$ and the insulin area under the curve all decreased significantly (all P < 0.05), while insulin sensitivity (HOMA-IR, QUICKI and Matsuda index) measured by OGTT improved significantly (P < 0.01). CONCLUSIONS: Moderate weight loss due to caloric restriction with reduction in insulin resistance improves glucose tolerance and insulin sensitivity in middle-aged obese women and thereby may help prevent the development of type 2 diabetes mellitus.

• Archives of Pharmacal Research
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• 제27권2호
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• pp.254-258
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• 2004

The purpose of this study was to investigate the pharmacokinetic alteration of diltiazem and its main metabolite, deacetyldiltiazem, after oral administration of diltiazem in rabbits with or with-out cimetidine co-administration. The area under the plasma concentration-time curve (AUC) of diltiazem was significantly elevated in rabbits pretreated with cimetidine, suggesting that the oral clearance, an index of intrinsic clearance, may be decreased by the cimetidine treatment. Consistent with the increased AUC by the treatment, peak plasma concentration ($C_{max}$) for diltiazem was also elevated. Apparent volume of distribution normalized by the bioavailability (($V_{d}$/F) of diltiazem increased sigrificantly in rabbits pretreated with cimetidine increased. Taken together with the fact that the first pass metabolism for diltiazem is the primary determinant for the oral bioavailability, these observations indicate that increases in the oral clearance and (($V_{d}$/F may be a manifestation of the decreased first pass metabolism. Consistent with the hypothesis, the AUC of deacetyldiltiazem was significantly decreased in rabbits with cimetidine treatment. Ratio of deacetyldiltiazem to total diltiazem in the plasma was significantly decreased in rabbits with cimetidine treatment. These observations suggested that the metabolism of diltiazem to deacetyldiltiazem was reduced by cimetidine treatment and that the dosage of diltiazem should be adjusted when the drug is co-administered chronically with cimetidine in a clinical setting.

• 약학회지
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• 제54권6호
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• pp.522-528
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• 2010

This study was designed to examine the effect of estrogen deficiency on the metabolism of ethanol in ovariectomized rats. Female rats were assigned to an ovariectomy (OVX) and a sham (SHAM) surgery group. Gain body weight was greater in incresed in OVX group and especially uterus weight significantly decrease depending on the concentration of estrogen after 3 month of ovariectomy. Ethanol at the tolerative dose (6 g/kg) was injected to rats by oral administration to measure the concentration of ethanol in blood. The area under the blood concentration time curve (AUC) was significantly lower in OVX group than SHAM group. The significant decrease in AUC in OVX group indicates that the estrogen deficiency leads to changes of the factors related to ethanol metabolism. Activity of hepatic alcohol dehydrogenase was not significantly influenced by the ovariectomy and also the ethanol elimination rate in vivo was not different. Cytochrome P450 isozymes did not show any changes except CYP 1A1 and 2E1. Level of hepatic glutathione in OVX group was higher after treatment of ethanol. Therefore the reduction of AUC appears not to be directly associated with the difference of ethanol metabolizing enzyme, but to be related with the physical factors like body weight.

• Clinical and Experimental Pediatrics
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• 제48권5호
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• pp.476-480
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• 2005

Immunosuppressive therapy in pediatric renal transplant recipients is changing consequence of the increasing number of available immunosuppressive agents. The optimal use of immunosuppressive agents requires a thorough understanding of the pharmacokinetic characteristics, but the information on the pharmacokinetic characteristics of these drugs in pediatric transplant recipients is still limited. In general, patients younger than 5 years old show higher clearance rates, therefore the need for higher dosages in younger patients seems evident. By the therapeutic drug monitoring, trough($C_{min}$) and peak level($C_{max}$) are measured and the area under the blood concentration-time curve(AUC), which is taken as being representative of total systemic exposure can be calculated. Cyclosporine A (CSA) has poor bioavailability, which contributes to high inter- and intra-patient pharmacokinetic variability. CSA concentration measured 2 hours after administration($C_2$) has better correlation with the AUC than $C_{min}$ and is an alternative technique that predicts the AUC. Tacrolimus(Tac) has a great deal of inter-individual variability like CSA but intra-individual variability in systemic exposure is considered to be low. Both CSA and Tac are metabolized by a cytochrome P-450 enzyme isoform(CYP3A4). We should consider changing the dosages when CSA or Tac is used in combination with the medicines that inhibit or induce the CYP3A4. In case of steroid-free immunosuppressive therapy, the blood concentration of Tac should be frequently checked and dosage adjustment may be needed.

• Journal of Pharmaceutical Investigation
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• 제31권3호
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• pp.161-165
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• 2001

Acebutolol (ABT) is almost absorbed after oral administration, but its bioavailability is reduced because of considerable first-pass metabolism in the gastrointestine and liver. The purpose of this study was to report the pharmacokinetic changes of ABT and its metabolite, diacetolol (DAT) after oral administration of acebutolol to control rabbits and rabbits with mild and severe folate-induced renal failure (FIRRs). Both of the area under the plasma concentration-time curve $(AUC^0_{\infty})$ of ABT and DAT were significantly increased in mild (p<0.05) and severe FIRRs (p<0.01), but the $AUC^0_{\infty}$ of DAT was more influenced than that of ABT in severe rabbits. There was a good correlation between serum creatinine and both of $AUC^0_{\infty}$ of ABT and DAT. The elimination half-life of ABT and DAT was significantly prolonged in mild (p<0.05) and severe (p<0.01) FIRRs, but the half-life of DAT was more influenced than that of ABT in severe FIRRs. The results suggest that the dosage of acebutolol should be adjusted according to the degree of renal disorder on the base of the serum creatinine concentration.

• Asian Pacific Journal of Cancer Prevention
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• 제17권11호
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• pp.4913-4916
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• 2016

Objective: As a source of information, medical data can feature hidden relationships. However, the high volume of datasets and complexity of decision-making in medicine introduce difficulties for analysis and interpretation and processing steps may be needed before the data can be used by clinicians in their work. This study focused on the use of Bayesian models with different numbers of nodes to aid clinicians in breast cancer risk estimation. Methods: Bayesian networks (BNs) with a retrospectively collected dataset including mammographic details, risk factor exposure, and clinical findings was assessed for prediction of the probability of breast cancer in individual patients. Area under the receiver-operating characteristic curve (AUC), accuracy, sensitivity, specificity, and positive and negative predictive values were used to evaluate discriminative performance. Result: A network incorporating selected features performed better (AUC = 0.94) than that incorporating all the features (AUC = 0.93). The results revealed no significant difference among 3 models regarding performance indices at the 5% significance level. Conclusion: BNs could effectively discriminate malignant from benign abnormalities and accurately predict the risk of breast cancer in individuals. Moreover, the overall performance of the 9-node BN was better, and due to the lower number of nodes it might be more readily be applied in clinical settings.