• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.386-389
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• 2008

It is important that the training stage of a supervised classification is designed to provide the spectral information. On the design of the training stage of a classification typically calls for the use of a large sample of randomly selected pure pixels in order to characterize the classes. Such guidance is generally made without regard to the specific nature of the application in-hand, including the classifier to be used. An approach to the training of a support vector machine (SVM) classifier that is the opposite of that generally promoted for training set design is suggested. This approach uses a small sample of mixed spectral responses drawn from purposefully selected locations (geographical boundaries) in training. A sample of such data should, however, be easier and cheaper to acquire than that suggested by traditional approaches. In this research, we evaluated them against traditional approaches with high-resolution satellite data. The results proved that it can be used small mixed pixels to derive a classification with similar accuracy using a large number of pure pixels. The approach can also reduce substantial costs in training data acquisition because the sampling locations used are commonly easy to observe.

• 응용통계연구
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• 제20권1호
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• pp.103-115
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• 2007

본 논문에서는 1차 자기회귀모형에서 자기회귀계수에 대한 여러 가지 추정량들의 분포함수에 대한 근사 방법에 대해 연구하였다. 자기회귀계수의 여러 추정량들을 이차형식의 관점에서 이해하고, Na와 Kim(2005)에 의한 안장점근사의 결과를 이용한 새로운 근사법을 제시하였다. 이 방법은 정규근사를 비롯한 기존의 근사법과는 달리 추정량에 대한 근사분포의 유도과정이 불필요하며, 소표본은 물론 통계적 추론의 주요 관심영역에서의 근사정도가 매우 뛰어난 장점을 가지고 있다. 모의실험을 통해 Edgeworth 근사를 비롯한 기존의 여러 근사법보다 효율이 뛰어남을 확인하였다.

• 한국조사연구학회:학술대회논문집
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• 한국조사연구학회 2000년도 춘계학술대회 조사연구의 방법론적 쟁점
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• pp.57-73
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• 2000

지방자체 실시에 따라 우리나라에서도 시. 군. 구 등의 소지역 통계에 대한 요구가 증대되고 있다. 하지만 정부통계 생산을 위한 표본조사의 경우 시(특할시, 직할시) 및 도별 통계생산을 목적으로 하기 때문에 신뢰성 있는 소지역 통계를 산출하는것이 불가능하고, 따라서 이런 소지역 통계생산을 위해 간접추정기법의 도입 및 활용하는 것이 필요하다. 본 논문에서는 정부통계 생산을 위한 소지역 통계기법의 도입 및 활용 가능성을 검토해 보기 위해 통계청에서 실시되고 있는 도소매업 및 서비스업 통계조사 중 인천직할시 숙박 및 음식점업의 총매출액에 대한 구별 소지역 통계를 산출할 수 있는 여러가지 간접 추정방법을 제시하고, 아울러 도소매업 총 조사 자료를 이용하여 제시된 간접추정량들의 효율성을 비교 분석해 보고자 한다.

• 대한한의학회지
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• 제19권1호
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• pp.179-204
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• 1998

The purpose of this research was to investigate the efficacy of Goiwhasan extract powder on the gastric injuries, antiulcer, gastrointestinal tract and blood hemostasis. Animals were used through this studies mice and rats. All animals were divided into 3 groups, contol group(no treatment), sample Ⅰ group(375mg/kg administration), sample Ⅱ group(750mg/kg administration). The gastric injuries and ulcer have been made by using pyloric ligation, indomethacin, HCI-ethanol, acetic acid and then The histological observation was followed. In the gastrointestinal tract, gastric juice secretion, gastric acidity, pepsin output, blood gastrin and secretin level, transport potentials in the small and large intestine were checked. And studies on blood hemostasis were performed on normal hemostatic activities and plasma prothrombin time, plasma recalcification time, plasma fibrinogen levels in the hypoprothrombinemic mice induced by warfarin. The results were as follows: 1. The antigastric ulcer effects on the pyloric ligation, indomethacin, HCl-ethanol, acetic acid induced gastric injuries were shown in Sample Ⅱ group(p<0.05). 2. Through the morphologic examination on the acetic acid induced ulcer, Sample Ⅰ group showed mild regeneration of epithelium and slight decrease of periulcer edema then that of Control group, while Sample Ⅱ group showed more retraction of round ulcer site, remarkable loss of swelling and edema then that of Control group, and revealing the regenerated epithelium in the surrounding ulcer site. Thus it was noted that both Sample groups have antigastriculcer effects on the experimentally induced gastric ulcer. 3. The inhibitory effects on gastric juice were noted in both Sample Ⅰ group(p<0.05) and Sample Ⅱ group(p<0.01). However, only Sample Ⅱ group showed the inhibitory effects on total acidity and pepsin output(p<0.05). 4. The significant inhibition of blood gastrin level showed at 30 min.(P<0.05) and 90 min.(P<0.05) after starting medication in only Sample Ⅱ group, but significance of blood secretin level in both groups was not recognized. 5. Any significant changes in barium sulfate transport in the small intestine of mice was not recognized in both groups, but the significantly inhibitory effect in large intestine was recognized in both Sample Ⅰ group(p<0.05) and Sample Ⅱ group(p<0.001). 6. In hemostatic effect on both normal mice and hypoprothrombinemic mice induced by warfarin, the significantly shortening effect on coagulation time was seen in only Sample Ⅱ group(p<0.01). 7. On plasma prothrombin time in hypoprothrombinemic rat induced by warfarin, Sample Ⅱ group have shortened the prothrombin time significantly(p<0.001). 8. On plasma reclcification time in hypoprothrombinemic rat induced by warfarin, the recalcification time have been shortened significantly in both Sample Ⅰ group(p<0.05) and Sample Ⅱ group(p<0.01). 9. On plasma fibrinogen levels in hypoprothrombinemic rat induced by warfarin, the fibrinogen contents in Sample Ⅱ have been decreased significantly(p<0.01). Overall the above results suggest that Goiwhasan has an therapeutic efficacy on antigastric ulcer and blood hemostasis. Further studies would be needed on the interaction of its herbal medicine and its mechanism in the future.

• 한국임상수의학회지
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• 제32권1호
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• pp.73-77
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• 2015

There has been increasing attention on sample size requirements in peer reviewed medical literatures. Accordingly, a statistically-valid sample size determination has been described for a variety of medical situations including diagnostic test accuracy studies. If the sample is too small, the estimate is too inaccurate to be useful. On the other hand, a very large sample size would yield the estimate with more accurate than required but may be costly and inefficient. Choosing the optimal sample size depends on statistical considerations, such as the desired precision, statistical power, confidence level and prevalence of disease, and non-statistical considerations, such as resources, cost and sample availability. In a previous paper (J Vet Clin 2012; 29: 68-77) we briefly described the statistical theory behind sample size calculations and provided practical methods of calculating sample size in different situations for different research purposes. This review describes how to calculate sample sizes when assessing diagnostic test performance such as sensitivity and specificity alone. Also included in this paper are tables and formulae to help researchers for designing diagnostic test studies and calculating sample size in studies evaluating test performance. For complex studies clinicians are encouraged to consult a statistician to help in the design and analysis for an accurate determination of the sample size.

• 한국임상수의학회지
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• 제31권4호
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• pp.288-292
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• 2014

A critical assumption of the standard sample size calculation is that the response (outcome) for an individual patient is completely independent to that for any other patient. However, this assumption no longer holds when there is a lack of statistical independence across subjects seen in cluster randomized designs. In this setting, patients within a cluster are more likely to respond in a similar manner; patient outcomes may correlate strongly within clusters. Thus, direct use of standard sample size formulae for cluster design, ignoring the clustering effect, may result in sample size that are too small, resulting in a study that is under-powered for detecting the desired level of difference between groups. This paper revisit worked examples for sample size calculation provided in a previous paper using nomogram to easy to access. Then we present the concept of cluster design illustrated with worked examples, and introduce design effect that is a factor to inflate the standard sample size estimates.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1125-1125
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• 2001

Micro-scale test methods are producing small-sample size where the conventional physical and chemical tests can not be used (high standard deviation, uncertain sampling conditions, low repeatability). Different small-scale test methods were developed recently for determination of physico-chemical, functional, rheological properties of wheat or wheat dough using miniaturized instruments with sophisticated sample preparation/handling and mechanics (RVA, 2 g mixograph, micro-Z-arm mixer, small-scale noodle maker, micro-baking method etc.). The small-scale methodologies can be used as basic research tools or as technology supported measurements and can be also essential in the early selection for quality traits in breeding programs. The milling as a sample preparation step is essential procedure providing good quality flour or semolina samples from small amount of grain (5-10 g) in a reproducible and reliable way. The aim of present study was to use NIR as quality control tool, and to evaluate the recently developed and manufactured micro-scale lab mill (FQC-2000) produced by Inter-Labor Co. Ltd., Hungary. The milling characteristics of the new instrument were compared to other laboratory mills and the effects of milling action on the chemical composition of fractions were analysed. The fractions were tested with both chemical and near infrared spectroscopic methods. The micro-scale milling resulted significantly different yields, particle size distributions and different fractions from compositional point of view. The near infrared spectra were sensitive enough to distinguish the fractions obtained by different milling procedures. Quantitative NIR calibration equations were developed and tested in order to measure the chemical composition of characteristic milling fractions. Special qualification procedure the PQS (Polar Qualification System) method was used for detecting the differences between fractions obtained by macro and micro-milling procedures. The results and the limitations of PQS method in this application will be discussed.

• Communications for Statistical Applications and Methods
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• 제17권3호
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• pp.337-347
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• 2010

대부분의 통계조사는 전국 및 시도단위와 같은 전체 또는 규모가 큰 지역을 위한 통계작성이 가능하도록 설계되어 있다. 그러나 최근들어 소규모 지역의 신뢰있는 통계결과에 대한 통계 이용자들의 요구가 점점 증가하고 있다. 경제활동인구조사는 전국 및 16개 시도를 위한 실업률을 매월 작성하고 있으나, 시군별 직접추정량은 적은 표본규모 때문에 신뢰도가 낮다. 본 연구에서는 경제활동인구조사에서 제공되는 실업자수에 대한 통계를 시군별로 작성하기 위한 모형을 제시한다. 이를 위해 보조정보로부터 "정보를 빌려오는(borrow strength)" 지역단위모형(Area level model)을 사용하였다. 제안된 모형 기반 추정(Model-based Estimation)은 모형 오차의 정규성 가정을 기반으로 하고 있으며, 평균제곱오차 측면에서 제안된 모형들을 비교하였다.

• The Journal of Asian Finance, Economics and Business
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• 제8권8호
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• pp.325-334
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• 2021

The study investigates the effectiveness of the macroprudential policy on credit growth in Vietnam. The authors use the logic of the transmission mechanism of macroprudential policy on credit growth. Research variables include economic growth, inflation, interest rate, and quarterly bank-level data from 28 commercial banks in Vietnam during 2011-2018. The results reveal that: (i) GDP growth had a positive impact on credit growth of small banks but had no impact on large banks, (ii) Domestic Systemically Important Banks (D-SIBs) and small banks respond differently to macroprudential measures of imposing different credit growth targets for different bank groups, (iii) Restrictions on foreign currency loans are found to be effective in curbing credit growth for the full sample and small banks, (iv) Inflation and economic cycle have significantly impacted credit growth at bank-level in Vietnam and (v) Interestingly, a significant positive relationship between interest rates and credit growth is found for the full sample and D-SIBs in Vietnam. The findings suggest that a stable macroeconomic environment should be good conditions for financial stability, and monetary authority should pay more attention to small banks' behaviors than D-SIBs behavior, toward such "administration" tools since small banks tend to prefer "breaking the rules" to make profits.

• 한국진공학회지
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• 제21권1호
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• pp.1-5
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• 2012

밀폐된 소형부품의 내부압력을 측정하는 장치를 개발하였다. 개발된 장치에서 실험한 시료의 내부압력은 43.151 kPa이었고 국제표준화기구에서 권장한 방법에 따라 계산된 확장불확도는 741 Pa이었다. 본 연구결과로 지금까지는 전혀 측정이 불가능 했던 밀폐된 시료의 내부압력을 측정할 수 있게 되었다.