• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.353-360
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• 2016

Recently, solar photovoltaic(PV) power generation which generates electrical power from solar panels composed of multiple solar cells, showed the most prominent growth in the renewable energy sector worldwide. However, in spite of increased demand and need for a photovoltaic power generation, it is difficult to early detect defects of solar panels and equipments due to wide and irregular distribution of power generation. In this paper, we choose an optimal machine learning algorithm for estimating the generation amount of solar power by considering several panel information and climate information and develop a defect detection system by using the chosen algorithm generation. Also we apply the algorithm to a domestic solar photovoltaic power plant as a case study.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.123-125
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• 2018

태양광발전시스템은 낮은 효율의 PV 패널을 사용하여 최대의 전력을 생산하기 위해 PV 패널의 최대전력점에서 운전하는 MPPT(Maximum Power Point Tracking) 제어가 반드시 필요하다. 기존의 MPPT 알고리즘은 대부분 경사법에 기초하고 있으며 그 중 대표적인 방법이 P&O(Perturb and Observe) 알고리즘이다. P&O 알고리즘의 MPPT 성능을 좌우하는 두 가지 인수는 MPPT 제어주기와 변량전압의 크기이다. MPPT 제어기의 빠른 동특성과 극대화된 효율을 위한 최적의 MPPT 제어주기와 변량전압의 크기를 결정하기 위해서는 실제 날씨 환경에서 다양한 일사량 프로파일 패턴에 대한 MPPT 제어기의 성능분석이 필수적이다. 본 논문에서는 대한민국 중부지역의 전형적인 맑은 날씨와 흐린 날씨에서 실제 일사량을 측정하고, 취득한 일사량데이터를 기초로 저자가 개발한 다이오드 등가모델을 적용하여 시뮬레이션을 수행하였다. 이를 기반으로 MPPT 제어주기의 설정값에 따른 PV 패널의 전력생산량을 예측하여 MPPT 목표 효율을 극대화할 수 있는 최적의 MPPT 제어주기를 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.49-51
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• 2003

가입자망과 메트로 광 가입자망에서 광범위한 적용범위에 대해 광 기술을 선도하는 기존의 WDM은 증가하는 사용자 수를 수용하는 데 어려움을 가지며 WDM은 채널간의 잡음에 의한 제한과 유효 채널의 최대가 WDM 채널에서 광 증폭기 이득의 균일성에 의해 제한받는다. 따라서 사용자 수를 증가시키고 데이터량을 확장시킬 수 있는 CDMA 기술 도입이 하나의 대안으로 요구된다. 본 논문에서는 SMF에서 수십 km 거리를 갖는 가입자망에서 Prime sequence code를 사용한 2.5Gb/s 광 COMA 신호의 색분산 패널티에 대해 연구하였다. 시스템 모델에서, 색분산 패널티, 파형과 디코드된 신호의 아이 다이어그램(eye diagram)이 결과로써 보여지며, prime sequence code 수의 증가에 대해 Chirp 파라미터를 갖는 코드화된 신호의 색분산 패널티를 보인다. 이러한 접근은 pseudo-orthogonality를 가지는 비동기식 광 CDMA의 디자인에 특히 적합할 것이다.

• Korean Journal of Construction Engineering and Management
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• v.15 no.4
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• pp.95-106
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• 2014

The outer surfaces of free form buildings contain panels with two-directional curvatures. To construct these panels, complex geometric surfaces should be divided into forms and sizes that can be manufactured and constructed efficiently. Because the bigger the curvatures of these panel, the more expensive the construction costs, these complex curvatures should go through optimal process of reinterpretation to minimize the curved surfaces with complex two-directional curvatures, which is called panel optimization. Small construction and design companies have trouble in calculating even rough estimate and cannot adjust expected construction cost of the panels based on comparison of design alternatives in conjunction with panel optimization process due to lack of knowledge and experience. This study conducts the research that can support designers' cost decision-making in the design stage of the free form buildings with respect to the panel optimization process. A 3D commercial application specialized to modeling free form shapes is used for the purpose.

• Korean Journal of Culture and Social Issue
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• v.22 no.1
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• pp.65-85
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• 2016

In this study, we examined the longitudinal change of multicultural acceptability, peer relationship, and teacher relationship using latent growth curve modeling. This study used data from the second, third, and fourth waves of the middle school student cohort (N=2,178) of the Korean Children-Youth Panel Survey (KCYPS). The dependent variable was multicultural acceptability. The independent variables were peer relationship and teacher relationship. The major longitudinal findings of this study are as follows: First, peer relationships, teacher relationships and multicultural acceptability increased with time. Second, peer relationship showed a significant effect on the multicultural acceptability over time. Finally, the teacher relationship showed a significant effect on the multicultural acceptability over time. These results show differentiation with previous cross-sectional studies of multicultural acceptability. Furthermore, it is expected that this study will provide educational implications for the cultivation of multicultural acceptability.

• The Journal of Bigdata
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• v.5 no.2
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• pp.135-143
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• 2020

This paper proposes a pre-processing method and a dimensional reduction method in the analysis of shopping carts where there are many correlations between variables when dividing the types of consumers in the agri-food consumer panel data. Cluster analysis is a widely used method for dividing observational objects into several clusters in multivariate data. However, cluster analysis through dimensional reduction may be more effective when several variables are related. In this paper, the food consumption data surveyed of 1,987 households was clustered using the K-means method, and 17 variables were re-selected to divide it into the clusters. Principal component analysis and factor analysis were compared as the solution for multicollinearity problems and as the way to reduce dimensions for clustering. In this study, both principal component analysis and factor analysis reduced the dataset into two dimensions. Although the principal component analysis divided the dataset into three clusters, it did not seem that the difference among the characteristics of the cluster appeared well. However, the characteristics of the clusters in the consumption pattern were well distinguished under the factor analysis method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.117-120
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• 2011

240 Hz 이상의 높은 프레임율을 가지는 LCD 기반 평판 FHD급 디스플레이 시스템은 높은 프레임율로 인하여 디스플레이 패널로 전송해야하는 유효한 데이터율이 1.9GB/s까지 이르게 되며, 수평/수직 동기를 감안하면 2GB/s 이상의 데이터 전송 대역이 필요하다. DRAM을 이용하여 이런 데이터 대역폭을 제공하려면 다수의 메모리 장치를 사용해야하기 때문에, 비용 상승, 전력소모량 증가 등의 문제를 야기한다. 이런 문제를 해결하기 위하여 본 논문에서는 JPEG 기반의 정지 영상 압축 시스템을 제안한다. 제안한 시스템은 8개의 디코더가 동시에 동작하는 구조를 가지고 있으며, 단일 데이터 열로부터 8개의 데이터 열을 용이하게 구분할 수 있도록 128-bit 데이터에 정렬된 64-bit 마커를 사용한다. 제안한 64-bit 마커는 마커 에뮬레이션을 야기하지 않도록 설계되었기 때문에, 인코더와 디코더의 구현 복잡도를 낮출 수 있고 단일 데이터열을 8개의 데이터열로 분리하는 작업을 매우 용이하게 한다.

• Journal of the Korean Society for information Management
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• v.38 no.4
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• pp.1-23
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• 2021

The purpose of this study is to analyze the effects of the bestseller ranks on the book circulations in public libraries. To achieve this goal, the weekly data sets of 179 books' library circulation and bestseller list from January 1, 2018 to December 29, 2019 were constructed based on the data collected from BigData MarketC and YES24. Three methods for analyzing panel data including linear regression, fixed-effect, and random effect models were compared, and it turned out that fixed-effect model was better than other methods. The results show that the average ranks of bestsellers were associated with their public library circulations visually. Also, the analysis of fixed-effect model showed that the single rank decline of a book on the bestseller list decreases its average circulation of 0.108 while the size of effect varied depending on subject of books. The study empirically demonstrated the impact of a bestseller list on people's book circulation behavior, suggesting that public libraries need to reference sociocultural context as well as bestseller book lists to predict library user needs and to formulate collection development policy.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1397-1405
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• 2014

Usually unit-nonresponse or item-nonresponse occurs in the survey. In case the rate of nonresponse is high, the analysis ignoring nonresponse may cause the wrong effect. The characterization of nonresponse is required. In a cross-sectional data, it is possible to study the characteristics of item-nonresponse but it is hard to study the characteristics of the unit-nonresponse. In order to identify the characteristics of the unit-nonresponse, this study used the first-year student of middle schools in the Korea children and youth panel survey (KCYPS) data. We investigated the handling situation of nonresponse and analyzed the characteristics of the unit-nonresponse. Most of the papers applied the way of getting rid of nonresponse, so that there was little paper using weights. In this paper, we compared the results of the analyses depending on whether the weight is used or not. The method of using weights showed statistically significant results much more than that of removing. More discussion will be needed.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.457-465
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• 2019

The purpose of this study is to identify factors that affect the language development of infants. For the analysis, data of three years from the first year (2008) to the third year (2010) of the 'Panel Study on Korean Children (PSKC)' were constructed and panel analysis was conducted. The subjects were 2,150 infants who participated in the questionnaire, and the language development of the infants was measured using the communication scores of the K-ASQ test provided by the Korean children's panel. In addition, the factors influencing the language development of infants derived from previous studies were introduced into the model. As a result of the analysis, it is shown that the fixed effect model with fixed individual error of the panel is suitable through the Hausman test. The higher the cognitive development level of the infant, the more positive parenting behavior of the infant, respectively. The conclusions and suggestions about the characteristics of the parents and the parents affecting language development were introduced.