• Journal of the Korean Geographical Society
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• v.46 no.3
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• pp.304-318
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• 2011

The types, distributional and shape properties of abandoned channels in Korea are classified and examined. There are 409 abandoned channels in Korea and they can be classified into the 6 types such as the incised meander cutoff, stream piracy, distributary, artificial incised meander neck-cutoff, channel straightening of free meander and distributary streams. The abandoned channels by incised meander neck-cutoff showing the most frequency with 266, have the topographical properties of high altitude and steep relief and frequently distribute in Gangwon and Gyeonbuk Province and in the upper reaches of main stream of Nakdong-River, and Dal-River and Pyeongchang-River, tributaries of Namhan-River. The most frequency areas of abandoned channels by distributary, channel straightening of free meander and distributary streams are the lower reaches of Namhan-River and main stream in the lower reaches of Nakdong-River, Mangyeong-River and Yeongsan-River, and Geumho-River, respectively. The abandoned channles by incised meandering neck-cutoff and stream piracy are relatively used as farmlands or forests due to the high altitude and relative altitude from the river bed.

• Korean Journal of Environment and Ecology
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• v.18 no.1
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• pp.61-74
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• 2004

The study was to investigate and compare plants and frequency of appearing species of vegetation transect in a straight and a restoration Section of Bulgwang stream in Seoul. Some part of Bulgwang stream was restored as a closed-to-nature stream. This present study consists of two investigations, the first investigation being conducted on May and the second one on August -September 2003. Based on the analysis of the data collected from both investigations, this study classified and listed all of the plants appeared in a straight and a restoration section of the stream. The study used the Belt-transect method in order to examine and analyze discover the appearance frequency of the vegetaton transect per 200 meters. During the period of the first investigation and the second one, plants of 33 families, 73 classes, and 88 species appeared in the straight section, while plants of 36 families, 76 classes, and 90 species appeared in the restoration section. The Naturalized Index of the straight section was 22.7％, and that of the restoration section was 21.1％. As shown on the results indicating that the Urbanization Index of the straight section was 7.8％, and that of the restoration section was 7.4％, the Urbanization Index of the straight section was slightly higher than the restoration section. The results using belt-transect analysis method showed that in case of the straight section, the plants of the highest appearance frequency on the riverside were Persicaria hydropiper and Humulus japonicus. On the contrary, in the case of restoration section, the plants showing a higher appearance frequency on the riverside were identified as Salix gracilistyla, Persicaria hydropiper, Rumex crispus, and Humulus japonicus. In conclusion, there was no difference between the straight and the restoration section in the bank with regard to vegetation transect. However, a remarkable difference was found on the riverside for the Salix gracilistyla which was introduced in the restoration section.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2010-2014
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• 2008

본 연구에서는 구하도 및 폐천 형성에 따른 시 공간적 하도 지형 변화를 정량적으로 파악하 기 위해 과거와 현재의 항공사진을 분석하였다. 항공사진은 청미천을 대상으로 하여 단기간의 인위적인 하천정비사업으로 인해 형성된 구하도의 형태 및 규모를 우선적으로 검토하였다. 그리고 하천의 종단 길이변화, 미지형 변화 등을 정량적으로 분석함으로서 인위적인 직강화 영향 후 하도 형태 변화를 예측할 수 있는 주요 요소들을 파악하였다.

• Journal of the Korean association of regional geographers
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• v.12 no.3
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• pp.352-363
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• 2006

The purpose of this paper is to analyze changes in the depositional landform in the channel of Cha-cheon, a branch stream of Nakdong river(main stream) since the artificial straight channel has been constructed in 1973. The results of analyses are as follow. First, the Cha-cheon has flooded over one time in a year, and flowed backward over three times annually, according to analyze the data of the Hyeonpoong Gauging Station of rainfall and water level during a decade(1993$\sim$2002). Second, the flood plain within the artificial straightened channel has a nearly plain profile between the small dike and last riffle(point A). Deposits thickness of flood plain reduce gradually toward upstream. Third, grain size distribution of the flood plain deposits(0$\sim$20cm) within the artificial straightened channel has a coarsening trend in downstream reach of C point. It implies that the backward flow of Nakdong river(the main stream of Cha-cheon) make effect on the depositional mechanism of lowest reach in Cha-cheon. Finally, the result of analyzing grain size distribution of the flood plain deposits(0$\sim$20cm) within the artificial straightened channel implies that the c-point is the boundary between the vertical deposition of suspended load due to the backward flow of Nakdong river and the deposition of bed load supplied from hillslope of Cha-cheon basin.

• Korean Journal of Ecology and Environment
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• v.51 no.4
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• pp.311-321
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• 2018

The purpose of this study is to investigate effect of stream channel naturalness on ecological health by using environmental factors and Fish Assessment Index (FAI) in the Han River of South Korea. These samples and data have been released from the research project titled Stream/River Ecosystem Survey and Health Assessment, which was conducted in 444 sites in the Han river watershed from 2008 to 2016. All samples were classified into five groups according to a degree of morphological changes of stream. Water chemistry analyses indicated a decline in water quality by decreasing stream channel naturalness, it is assumed that channelized stream was vulnerable to aquatic pollution compared to the natural meandering stream. In the result of frequency of dominant species, sensitive species and insectivore such as Zacco koreanus, Rhynchocypris kumgangensis and Pungtungia herzi were frequently dominated in the natural meandering stream while tolerant species and omnivores such as Carassius auratus and Cyprinus carpio were more dominated in the channelized streams. The FAI in the channelized stream shows decline to average of $46{\pm}25$ compared with that of the natural meandering stream ($80{\pm}20$). The decrease in FAI was highly influenced by changes in matrixes of fish assemblage structure such as number of sensitive species (M3), portion of omnivores (M5) and insectivores (M6). Moreover, annual average FAIs from 2008 to 2016 were significantly correlated with water chemistry, especially TN, TP and BOD ($r^2=0.59$, p<0.0001). Taken together, all the results suggest that the stream channelization could negatively impact on the water quality and fish assemblage structure, leading to degradation in aquatic ecosystem health.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.275-279
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• 2011

본 연구는 낙동강 본류의 하도준설로 인하여 본류에 유입하는 지류하천의 하상고와 본류와의 하상고간의 높이차가 크게 발생됨에 따른 지류하상 안정화 기법을 금호강을 대상으로 검토하였다. 지류하천의 하상고와 본류와의 높이차가 크게 발생됨에 의해 하천을 직강화하여 첩수로를 만들게 되고 하상 경사는 커지게 된다. 이 경우 유량과 하상 재료의 변화는 없으므로 Lane 식에서 우변 하상 경사의 증가는 좌변의 증가를 가져오며 따라서 유사량의 증가를 가져온다. 즉 하천이 급해지면서 유사량이 증가한다. 이에 따라 직강 구간에서 하상의 세굴을 가져오게 된다. 실제로, 하천 개수 사업에서 직강화는 하상의 세굴과 저하보다는 통상 하폭의 확대를 가져온다. 지류 입장에서는 본류 수면이 일종의 기준면이 되므로 기준면의 저하를 의미하며, 이는 지류 에너지 경사의 증가를 의미한다. 이 경우 Lane 관계식에서 하상 경사의 증가는 좌변의 증가를 가져오며, 하상 재료가 일정한 상태에서 이는 유사량의 증가를 가져온다. 즉 지류의 하상 경사와 유사량 증가는 하상의 침식을 의미하며, 이러한 침식은 상류로 진행된다. 이를 두부 침식이라 한다. 따라서 본 연구에서는 낙동강 본류하도 준설에 따른 지류하상의 하상변동과 지류유입 토사량에 대해서 검토하겠다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.201-201
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• 2011

본 연구는 국내 하천에서 방치되고 있는 구하도 구간의 물리적 상태를 파악함으로써 이를 보전 또는 관리하기위한 기초자료로써 활용하고자 한다. 국내의 구하도 구간은 자연적인 발생보다는 하천의 직강화, 하천부지 이용의 고도화 등 인위적인 교란으로 인해 형성된 것이 대부분이다. 이와 같이 사행구간의 하도가 절단(Cutoff)됨으로써 형성된 구하도는 우각호 형상의 습지형 구하도와 이미 육역화되어 농경지나 나대지로 이용되는 육화형 구하도로 구분할 수 있다. 특히 폐천(Abandoned Channel)화가 진행된 대부분의 습지형 구하도는 수질, 생태계, 육역화, 농업용수 이용 등 다양한 문제점 및 현안을 가지고 있기 때문에 이에 대한 보전 또는 관리가 필요하다. 이를 위해서는 우선적으로 습지형 구하도의 현재를 진단하고 평가하기 위한 연구가 선행되어야 한다. 따라서 본 연구에서는 습지형 구하도를 평가하기 위한 평가지표를 제안하고 이를 만경강 습지형 구하도 5개소에 적용하였다. 평가지표는 국내외에서 제안된 하천환경 평가지표와 RAM(일반기능평가기법)을 토대로 작성하였다. 이 평가지표는 단절된 습지구간에 적정한 지표, 자료 획득의 용이성, 즉시 적용 가능한 것을 우선순위로 선정하였다. 평가지표는 자연도, 서식처, 친수, 수질 등 4개 지표를 세분화한 총 25개 항목으로 제안하였다. 만경강에 대한 물리적 평가결과 습지형 구하도의 경우 서식처, 자연도 부분이 높은 점수를 획득한 반면 수질과 친수 지표는 상대적으로 취약한 것으로 평가 되었다. 이와 같은 결과는 향후 만경강 습지형 구하도에 대한 보전 및 관리계획을 수립함에 있어 주요 고려사항이 될 수 있을 것이다.

• Korean Journal of Labor Studies
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• v.24 no.1
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• pp.157-196
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• 2018

This study analyzes non-standard workers' attitudes and behaviors towards standard workers' strikes using the case of a joint strike held by journalists at KBS and MBC in 2012. Tracing the process since 2008 by which a conservative government has tried to control the press and regular journalists have collectively resisted against it, we put our analytical focus on two major groups of freelance broadcast professionals: independent producers and writers in current affairs. Specifically, we examine 1) how they perceived and responded to a series of regular journalists' struggle to protect journalistic value, 2) how such perception of and response to regular journalists could be developed, and 3) how (de)solidarity could form and then deepened between freelance and regular journalists in the 2012 Media Strike. Our findings show that the ways in which regular journalists had controlled freelance journalists at work affected the relationship between class-based and occupation-based rationality freelance journalists held in their minds. Independent producers, who had developed a strong class-based rationality in response to the coercive input-output control, showed cynicism about regular journalists' strike pointing out their hypocrisy and contradiction. In contrast, freelance writers accommodated and joined the strike by regular workers in the spirit of solidarity based on occupational rationality which had developed from normative, process control. Our paper ends with theoretical and practical implications.

• The Journal of the Korea Contents Association
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• v.18 no.6
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• pp.643-651
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• 2018

The purpose of this study is to explore which factor influences on the happiness of full-time contingent worker at workplace. The study used the data of 12th Korean Education Employment Panel(KEEP), and occupied hierarchical multiple regression analysis to examine which factor affected their happiness in particular focused on job satisfaction and work characteristics of them. The results of the study showed firstly, work satisfaction and communication in workplace impacted on employees' happiness. Secondly non-regular worker's own education and skill affected on happiness, and also clearly communication and work satisfaction impact on their happiness as well as regular workers. Finally the research recommended that organization should analyze job related knowledge and skill their contingent employees hold before allocating them and help their happiness in order to organization's productivity and value creation.

• Information and Communications Magazine
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• v.33 no.2
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• pp.28-38
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• 2016

기존 인터넷의 보안 모델은 모든 통신 상대와 통신 환경에 대한 의심을 기반으로 외부의 공격으로부터 자신을 보호하는 모델이다. 그러나 이 보안 모델은 공격이 지능화됨에 따라 방어도 지속적으로 강화되어야 하는 악순환의 고리에 빠지게 된다. 이런 악순환의 고리를 끊기 위하여 상호 신뢰를 바탕으로 공격자체가 원천적으로 없어지는 신뢰통신 구조를 제안한다. 신뢰통신모델은 먼저 상호신뢰 관계를 가진 제한된 참여자들로 구성된 신뢰 도메인에서 시작하여 외부와의 통신은 잘 정의된 인증 절차에 따라 허용함으로써 도메인의 신뢰 수준을 유지하면서 신뢰 영역을 확장하는 방식을 채택한다. 이 신뢰 모델을 기반으로 신뢰 네트워크 구조를 제안하고 이 구조를 기존의 IP 네트워크에 적용하는 방안을 제시한다.