• Journal of Energy Engineering
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• v.23 no.3
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• pp.203-210
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• 2014

In this study, combustion behaviour were to analyze by comparing experimental data against predicted values. In developing pellet boiler performance, various factors such as combustion chamber shape, input air velocity, the amount of fuel, temperature, and fuel characteristics need to be analyzed. Analytical model using a numerical method is useful to overcome time and cost consuming by practical experiment. By controlling feeding rate of fuel, flue gas composition and temperature distribution obtained form experiment were compared with predicted values using FLUENT(ANSYS, Inc., Southpointe). Measurement were in good agreement with model predictions : with 0.60 % for $CO_2$ 0.73% for $O_2$ when compared with independent data sets.

• Journal of Digital Convergence
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• v.13 no.12
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• pp.179-185
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• 2015

Along with the recent advances of mobile internet technology, use of social network service(SNS) is very common among adolescents or college students in their daily lives. Although there have been a lot of studies on Internet addiction or mobile phone addiction, however, there were little research on SNS addiction so far. Scholars investigated somewhat broader and obscure phenomenon of Internet addiction. In this regard, the current study tried to examine factors which influence SNS addiction behavior. Unlike Internet addiction, there are positive influencing factors such socialization, enjoyment as well as problematic ones like loneliness. Data were collected from college students in Korea to examine how those factors influence addiction behavior and hypotheses were tested using the partial least square method. All three factors, socialization, enjoyment, and loneliness, were found to significantly influence SNS addiction and socialization was positively associated with enjoyment.

• Journal of the Korean School Mathematics Society
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• v.20 no.3
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• pp.239-254
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• 2017

The study in this paper considers how high school students' attitudes toward and interest in mathematics could be promoted by conjoining the learning of ma thematics with the learning of social science topics. Survey instrument was dev eloped to measure student attitudes toward mathematics and social science subje cts and to evaluate student beliefs on learning mathematics embedded in social science topics. Data were collected from high school students in Korea by admi nistering pre- and post-tests: students were intervened with examples of math problems embedded in certain social contexts. The findings indicate that high sc hool students' experience of solving mathematics problems embedded in social c ontexts positively affects the promotion of their attitudes toward and beliefs on both mathematics and social science subjects.

• Archives of design research
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• v.13 no.4
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• pp.225-231
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• 2000

Forcasting the future is a very important task in design situation analysis. To do this, the reduction of life style, the tendency of product differentiation and individuality should be considered along with such changes as cultural, economical and social trends. At the moment, industrial structure is being reorganized from centering around the manufacturing industry to the distribution industry and consumers. Consumers show the attitude of expressing their individualities on the basis of various tastes rather than standardization. The flow of information also has been changing rapidly from the former types of information provided by producers to the age when consumers pursue the objective and model of information. Therefore, we are able to say that picking up the trends around the streets becomes more important than ever. Accordingly, the objective of this study is to establish a system which is able to effectively carry out the trend analysis by a town watching method, the construction of a database with collected data, and its practical application on the web.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1417-1421
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• 2009

최근 들어 유역의 정확한 수문현상을 파악하기 위하여 유역의 유출량 자료를 직접 유출과 기저유출로 분리한 후 수문 모형의 직접유출 및 기저유출의 수문컴포넌트 검증에 활용하는 연구가 많이 이루어지고 있다. 미국 국립지리국 (USGS) 에서 개발한 HYSEP 모형이 지난 수 년 동안 유출 컴포넌트 분리에 널리 이용되어 오고 있다. 그러나 USGS 기반의 HYSEP의 경우 능숙한 컴퓨터 사용자가 아닌 비전문가들이 HYSEP을 운영하기에는 여러 가지 많은 제한점이 있어 왔다. 그리하여 본 연구에서는 고해상도 위성영상 Google Map 기반의 기저유출분리 프로그램인 Web-based HYSEP 인터페이스를 개발하였다. 이 시스템에는 HYSEP에서 제공하는 3가지 방법인 Fixed Interval / Sliding Interval / Local Minimum 방법이 제공되고 있다. 본 연구에서 개발된 Google Map 기반의 HYSEP 시스템은 USGS 유량 관측지점들에 대해 XML 데이터 포맷으로 DB를 구축하여 Google Map 과 연계하였으며 이를 통해 사용자가 원하는 관측소의 실시간 유량자료를 다운로드 할 수 있도록 개발되어졌다. Google Map 기반의 HYSEP 기저유출 분리 시스템(http://www.EnvSys.co.kr/${\sim}$hysep)은 Perl/CGI 및 자바스크립트, Google Map script 등을 이용하여 개발되었다. 현재 개발된 Google Map 기반의 USGS HYSEP 시스템은 한 곳의 유량관측지점에 대해서 총 3가지 기저유출 모듈을 적용하여 결과를 제공하고 있으며, 그 결과를 테이블이나 그래프 형태로 제공하도록 되어 있다. 본 연구에서는 Google Map 기반의 USGS HYSEP 시스템을 이용하여 미국 인디애나 주의 Little Eagle Creek 유역의 유량자료와 Fixed Interval / Sliding Interval / Local Minimum 방법을 이용하여 기저유출을 분리하였으며, 기존에 널리 활용되는 기저유출 분리 프로그램인 Web 기반의 WHAT 시스템 (http://www.EnvSys.co.k.r/~what) 산정 기저유출량과 비교분석하였다. 분석결과 HYSEP 예측 기저유출치가 전반적으로 WHAT 예측치보다 크게 산정되었다. WHAT 시스템과 본 연구에서 개발한 Web 기반의 HYSEP 일단위 기저유출량을 비교해 본 결과 $R^{2}$가 0.56, EI는 0.52로 어느 정도 비슷한 경향을 나타냈으나, 유역의 특성을 반영하는 WHAT 시스템과는 달리 주어진 유량자료만을 이용하여 기저유출을 분리하는 Web 기반의 HYSEP 기저유출 분리모듈을 개선할 필요가 있는 것으로 판단된다.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.145-151
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• 2009

Recently the water quality management policy has been changed from managing the point source to controlling the nonpoint sources (NPSs) because of TMDL program. Most NPSs are accumulated on the surface during dry periods. These accumulated pollutants are washed-off during a storm event and highly impairing the water quality of the receiving water bodies. Usually NPS has high uncertainty and is hard to control because of the variability of the rainfall and watershed characteristics. Also, NPS is derived from various land uses. The Ministry of Environment (MOE) is studying and monitoring the pollutant loads from each land use since 2007 to determine the unit pollutant loads. This research was a part of long-term monitoring program conducted to characterize the washoff and provide the mean EMC of artificial grassland. The average EMCs result of BOD, COD, DOC, SS, TN, NH4-N, NO3-N, TP, and PO4-P of the artificial grassland were deterined to 8.2, 17.5, 11.3, 110.1, 3.07, 0.20, 0.75, 0.86 and 0.08 mg/L, respectively. The results of statistical analysis conducted showed a low correlation to the contaminants.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.671-679
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• 2016

We investigated subgroups within a global communication network to improve the empirical understanding of global communication phenomenon from the social network perspective. We collected global communication data from Twitter and constructed a global communication network. We also added countries' geographic and economic properties used in the United Nations and the World Economic Forum. We analyzed the subgroups' structure within the global communication network using centrality analysis, core-peripheral analysis, and cohesion analysis. We also detected communities embedded within the global communication network with modularity-based community detection methods. We found that the core countries occupy central positions in the global communication network and there is a hierarchical communication structure among the economic subgroups. Futhermore, we discovered some communities within the global communication network and found that countries within the communities can have homophily such as economy, geography, history, culture, and religion.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.51-57
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• 2016

Many kinds of telemetry should be monitored to check the state of spacecraft and it leads the time consumption. However, it is very important to define the status of satellite in short time because the contact number and time of low earth orbit satellite is limited. Also, on-board fault management should be prepared for non-contact operation because of the sever space environment. In this paper, on-board and ground autonomous operation method for the safety enhancement is described. Immediate fault detection and response is possible in ground by explicit anomaly detection through satellite event and error information. Also, satellite operation assistant system is proposed for ground autonomy that collect event sequence in accordance with related telemetry and recommend or execute an appropriate action for abnormal state. Critical parameter monitoring method with checking rate, mode and threshold is developed for on-board autonomous fault management. If the value exceeds the limit, pre-defined command sequence is executed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.2 s.332
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• pp.23-38
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• 2005

The state of channel between two or more wireless terminals is changed frequently due to noise or multiple environmental conditions in wireless network. In this paper, we analyze packet transmission time and queue length in a time-varying channel of packet based Wireless Networks. To reflect the feature of the time-varying channel, we model the channel as two-state Markov model and three-state Markov model Which are transformed to SFG(Signal Flow Graph) model, and then the distribution of the packet transmission can be modeled as Gaussian distribution. If the packet is arrived with Poisson distribution, then the packet transmission system is modeled as M/G/1. The average transmission time and the average queue length are analyzed in the time-varying channel, and are verified with some simulations.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1231-1239
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• 2013

Recently, successful management of the brand is more important than anything else to enhance the competitiveness of enterprises and increase customer loyalty. Most customers evaluate value and image of an enterprise in accordance with their experience of its goods and service. This study focused on the Fisheries Cooperative Association representative brand for the marketing point of view and attitude shall establish a scheme that can identify. We suggest a model that can measure the brand equity index (BEI) for equity. Based on the survey, we intended to provide the strategic direction and derive important factors for improving brand equity.