• Membrane Journal
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• v.22 no.6
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• pp.441-449
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• 2012

Effect of humic acid (HA) with periodic nitrogen back-flushing was investigated in hybrid process of alumina microfiltration and photocatalyst for drinking water treatment. It was compared and investigated with the previous results of microfiltration water back-flushing or ultrafiltration nitrogen back-flushing in viewpoints of membrane fouling resistance ($R_f$), permeate flux (J), and total permeate volume ($V_T$). As results, the trends of membrane fouling were different depending on nitrogen or water back-flushing, and depending on ultrafiltration or microfiltration made with the same material. Also, the nitrogen back-flushing using microfiltration was more effective membrane fouling inhibition than ultrafiltration, and the nitrogen back-flushing was more effective than water back-flushing using the same microfiltration membrane. Turbidity treatment efficiencies were almost constant independent of HA concentration, but HA treatment efficiency was the maximum at HA 10 mg/L. From this results, it was shown that the treated water HA quality increased as increasing HA concentration, but HA could be removed the most effectively by photocatalyst beads adsorption and photo-oxidation at HA 10 mg/L.

• The Journal of the Korea Contents Association
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• v.21 no.9
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• pp.164-175
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• 2021

The purpose of this study is to develop the 'Kkondae Scale' and verify its validity. For this purpose, three constructive concepts (attribution error, cognitive rigidity, and one-way communication) were derived through expert interviews, prior research and literature analysis, and 15 preliminary questions were selected. In addition, a preliminary scale was developed by modifying or adding items to conform to each constructive concept through expert content validity evaluation. Next, as a result of the exploratory factor analysis of about 250 adults, a three-factor structure model was derived. As a result of the confirmatory factor analysis on the preliminary scale for about 401 adults, it was confirmed that the fit of the three-factor structure was good. As a result of convergence and discriminatory validity analysis, it was confirmed that the developed scale was a valid tool to measure Kkondae by showing appropriate correlations with listening attitude, empathy, acceptance of others, and intellectual humility. Finally, based on the results of this study, the significance, limitations, and future research direction of the study were discussed.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.335-335
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• 2012

기후변화에 의한 미래 수문량 전망에 대한 연구는 전지구 모델 결과를 바탕으로 이루어진다. 현재 전지구 모델의 모의 결과 생산된 강우 자료는 기상청에서 제공되며, 제공된 자료는 기상청 관측 지점에 국한되어 있다. 어떤 유역의 확률홍수량 전망은 유역내 강우 지점의 확률강우량을 강우-유출 모형인 HEC-1에 입력하여 추정할 수 있다. 한강 유역과 같은 대유역의 확률홍수량을 구하기 위해서는 유역내 기상청 관측 지점만으로는 지점수가 부족하기 때문에 국토해양부나 수자원공사 관할의 지점 자료를 활용한다. 하지만 이러한 대유역의 미래 확률홍수량을 전망하고자 하는 경우에 제공되는 전지구 모델 결과가 기상청 지점에 국한되어 있어 다른 지점의 확률강우량을 산정하는 데 어려움이 있다. 본 연구에서는 이러한 문제를 보완하기 위해 지역빈도해석을 이용하여 미래 전망 자료가 없는 지점들의 확률강우량을 추정하였다. 지역빈도해석을 수행하기 위해서는 관측 자료가 있는 유역내 지점들의 특성치(site characteristics)를 바탕으로 지역을 구분하고, Hosking and Wallis(1997)가 제안한 이질성 척도(heterogeneity measure)를 근거로 구분된 지역의 수문학적 동질성 여부를 검토하며, 각 지역에 대한 성장곡선(growth curve)를 추정한다. 지역별로 추정된 성장곡선에 지점의 연최대값 평균을 곱하면 그 지점의 확률강우량을 추정할 수 있다. 따라서 미래 기간의 지역별 성장곡선과 지점의 연최대값 평균을 전망할 수 있으면, 미래 기간의 지점별 확률강우량을 산정할 수 있고, 이를 바탕으로 확률홍수량도 전망할 수 있다. 이를 위해 본 연구에서는 전지구 모델에서 모의된 강우 자료를 바탕으로 미래 기간의 성장곡선을 추정하고, 과거 대비 미래 기간의 지속기간별 연최대값 평균의 비율을 산정하여 모의 자료가 없는 지점에 적용함으로써 미래 기간의 연최대값 평균을 산정하였으며, 이를 바탕으로 미래 기간의 확률강우량을 산정하도록 하였다. 이 기법의 신뢰도를 검증하기 위해 관측 자료를 두 기간으로 구분하여, 이 기법을 적용하여 추정한 확률강우량과 관측 자료로부터 산정한 확률강우량을 비교하였다.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.4
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• pp.455-460
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• 2003

A new cluster validity index is proposed that determines the optimal partition and optimal number of clusters for fuzzy partitions obtained from the fuzzy c-means algorithm. The proposed validity index exploits an overlap measure and a separation measure between clusters. The overlap measure is obtained by computing an inter-cluster overlap. The separation measure is obtained by computing a distance between fuzzy clusters. A good fuzzy partition is expected to have a low degree of overlap and a larger separation distance. Testing of the proposed index and nine previously formulated indexes on well-known data sets showed the superior effectiveness and reliability of the proposed index in comparison to other indexes.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.97-105
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• 2008

The various mutations of the malicious codes are fast generated on the network. Also the behaviors of them become intelligent and the damage becomes larger step by step. In this paper, we suggest the method to select the useful measures for the detection of the codes. The method has the advantage of shortening the detection time by using header data without payloads and uses connection data that are composed of TCP/IP packets, and much information of each connection makes use of the measures. A naive estimator is applied to the probability distribution that are calculated by the histogram estimator to select the specific measures among 80 measures for the useful detection. The useful measures are then selected by using relative entropy. This method solves the problem that is to misclassify the measure values. We present the usefulness of the proposed method through the result of the detection experiment using the detection patterns based on the selected measures.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.338-339
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• 2011

본 연구는 해양플랜트 지원선 중 작업자들에게 전용거주시설을 제공하는 생활바지선 거주구공간계획에 관한 연구이다. 생활바지선의 거주구는 '작업자영역', '서비스영역', '승무원영역', '업무영역'으로 공간을 분류할 수 있다. 본 연구에서는 현재 사용되고 있는 10척의 생활바지선 일반배치도(GA)를 조사하여 거주공간특성을 분석하였다. 또한 해양플랜트 거주구 설계시 가장 많이 참조되는 ABS, NORSOK 등 해외선급협회에서 제시하는 해양플랜트 거주구 공간설계지침을 분석하여 생활바지선에서 거주구 공간계획에 적용하기위한 설계지침을 제시하였다. 그리고 생활바지선 거주구 설계모델을 설정하고 모델을 대상으로 데크별 공간배치와 동선을 계획하였다. 마지막으로 거주구 설계모델의 객실, 식당, 주방, 휴게공간 그리고 위생시설 등 주요공간을 대상으로 공간계획을 실시하고 계획안을 제시하였다. 최근 국내 조선업계에서도 생활바지선에 대한 관심이 증가하고 있으나 거주구 공간설계기술의 부족으로 외국 설계업체에 의존하고 있는 형편이다. 따라서 우선 한국선급협회에서 본 연구결과를 기초 생활바지선 거주구 공간계획을 위한 설계지침을 시급히 만들어야만 한다.

• Journal of Korean Society for Quality Management
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• v.27 no.4
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• pp.229-240
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• 1999

Drawbacks of using sigma level as a performance metric is reviewed. The concept of sigma level is introduced and methods of calculating sigma levels for various cases are illustrated with examples. Drawbacks of using sigma level as performance metric are also discussed with some suggestions for overcoming them.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.169-171
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• 1998

막오염을 저감하는 여러 방법중의 하나인 backpulsing은 짧은 시간동안 고빈도로 역세척을 하는 것이다. 본 연구는 주기적인 역충격(frequence backpulsing)에 의한 중공사막의 오염을 줄이는데 있어서 적절한 역세 주기를 구하기 위하여 막이 오염되기 이전의 순수투과능을 나타내는 시간인 임계시간(critical time)을 구하는 것이 목적이다.

• Journal of the Korean Data and Information Science Society
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• v.27 no.5
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• pp.1285-1291
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• 2016

To quantify an concept we often use Likert summated rating scale of original or standardized variables in case the variables are relatively less. When variables have different scales, standardized values tends to be used rather than the original values. This is also true in evaluating systems. For example, we may use standardized values of local tax levy, population, and etc. and use the summed value of the standardized values to access the degrees of development. In this paper, we propose using a data-driven weighted sum for a scoring system and the way how to obtain the weights. We apply the proposed method to a real data set and find that proposed method is better than the usual summated rating scale.

• Journal of the Korean Society of Safety
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• v.13 no.1
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• pp.147-154
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• 1998

The objective of this study was to evaluate quantitatively the effects of handle types of garden tools on the ergonomic effectiveness, user satisfaction in terms of work performance, and subjective judgment of tactile feel and control. The approach was to compare garden tools with conventional wood handle and newly developed fiberglass handle, and to utilize three different tools: shovel, rake, and hoe. The hollow fiberglass handle was 12% more efficient than either the wood or solid fiberglass handle. The next important measure was the subjective ratings of the perceived exertion averaged across three different tools. The average ratings for the hollow fiberglass handle were the smallest. In conclusion, the hollow fiberglass handle showed better efficiency and better subjective acceptability for comfort, tactile feel, and especially decreased slipperiness.