• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.76-76
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• 2018

하천에서의 유사이송과 하상변동을 분석하는 대표적인 방법으로는 현장에서 유사량이나 하상고를 측정하여 분석하는 실측에 의한 방법, 수리모형 실험과 수치모형을 이용하는 방법이 있다. 이 중에서 실측에 의한 방법은 시간과 비용의 한계로 수치해석모형을 이용한 연구가 많이 이루어 지고 있다. 현재까지 개발된 다양한 하상변동 수치모형들은 유사이송 상태를 평형 유사이송 상태를 가정하고 개발되어 왔다. 평형 유사이송은 흐름과 하상재료 등의 조건이 발생시킬 수 있는 유사이송능력과 실제 유사이송률이 동일하다고 가정하는 것이다. 그러나, 실제 유사이송에서는 흐름 및 지형 등의 변화에 따라서 지속적으로 새롭게 형성되는 유사이송능력에 실제 유사이송률이 빠르게 도달하지 못하면서 유사이송능력과 유사이송률 사이에 시 공간의 격차가 발생하게 된다. 이러한 상황을 비평형 유사이송이라고 하며 지속적인 하상 상승 및 저하가 발생하는 구간, 댐과 같은 구조물에 의해서 유사의 연속성이 차단되는 구간, 하상재료가 불연속한 구간 등에서 주로 발생하는 것으로 알려져 있다. 비평형 유사이송을 수학적으로 모의하기 위한 대표적인 방법에는 적응거리계수와 회복계수를 이용하는 방법이 있다. 위의 계수들은 흐름 및 하상 특성을 이용하여 공간에 대한 유사이송의 지체현상을 고려하는 방법으로 이를 산정하기 위한 다양한 공식들이 제시되고 있다. 그러나, 각 공식들에 의해서 제시되는 값에 많은 차이가 있는 것으로 알려져 있다. 본 연구에서는 실내실험과 수치실험을 통해서 평형/비평형 유사이송 및 집중형/분포형 적응거리계수를 고려한 모의 결과를 비교하였으며, 적응거리계수 산정공식에 따른 비평형 유사이송 모의 결과를 비교하였다. 본 연구에서 적용한 실내실험에 대해서는 평형 유사이송보다는 비평형 유사이송을 고려한 경우와 비평형 유사이송 공식을 이용하여 적응거리계수를 분포형 매개변수로 이용하는 경우가 실제 하상변동 모의 결과에 더 근접한 수치실험 결과를 제공하는 것으로 나타났다.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.568-573
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• 2023

Range resolution is the ability to distinguish different targets placed in same angular direction but at different distances from the radar. Normally, Range resolution requirement is defined as the width of transmitting pulse. The width of transmitting pulse does not mean the ability to distinguish two different targets. Range resolution performance to detect and track targets separately depends on the signal processing and tracking algorithm not only the width of transmitting pulse. This paper analyzes the processing steps in algorithms to affect the range resolution performance and verifies the results by roof-lab ground test using beacon signal. As a result, to track targets with the same angular position separately, it is desirable to have larger range difference than plot-track association test gate.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.97-109
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• 2014

Social media is a general term for online services by which users share opinions, perspectives, and experiences. It supports interactions between users in sharing contents on it and weak ties among them play an important role in the process. This exploratory study attempts to identify crucial factors of establishing weak ties between social media users in the perspective of social network theory and uncertainty reduction theory. We collected data through diary study and in-depth interview and analyzed it following grounded theory approach. As a result, social media users more actively interacted each other or shared contents based on weak ties, compared to strong ties. In addition, similarity, self-disclosure, and relevance appeared to facilitate establishment of weak ties, by reducing psychological distance between social media users and perceived uncertainty of them.

• Journal of KIISE:Information Networking
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• v.32 no.5
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• pp.625-632
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• 2005

Recently, real time services have been demanding a lot and the number of mobile devices is increasing extremely. Many researchers are focusing on decreasing handoff or signaling cost, produced when mobile devices are moving around. With these efforts, HMIPv6(Hierarchical Mobile Internet Protocol Version 6) was proposed. Mobile nodes do not need to register their locations to Home Agents whenever crossing over subnets within a MAP domain. In HMIPv6, mobile nodes choose the farthest MAP without considering node mobility pattern. However, a large MAP domain is not always efficient for a slow moving node and required additional work to choose a MAP in HMIPv6. Hence, this paper proposes 'Performance Analysis of HMIPv6 applying adaptive MAP Domain Site'.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.728-728
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• 2012

본 연구에서는 자연하상 복원을 위한 하상복원공법을 개발하여 시험구간에 적용하였다. 공법적용 대상 지역은 안양시역내의 안양천 일정구간으로 화창교로부터 상류방향으로 약 500m 거리에 웅덩이 수제공법이 적용되어 있으며, 그로부터 다시 상류방향으로 130m 떨어진 거리에 낮은 바닥막이 공법이 적용되어 있다. 낮은 바닥막이 공법의 경우 완만한 곡류사주의 직상류 부로서 강한 수류와 함께 빠른 유속이 형성될 경우 하상의 세굴이 예상되어 이를 방지하기 위해 저수로의 유하방향으로 완만한 호형으로 설치하였으며, 웅덩이형수제 공법은 완만한 곡류로 좌안 수충부가 형성되어 있어 물의 흐름방향과 유속을 제어하여 흐름에 의한 호안침식을 방지하기 위해 현 위치를 선정 및 적용하였다. 첫 번째, 경관모니터링 결과 낮은 바닥막이 공법과 웅덩이 수제 공법을 적용한 구간에서 대규모 홍수 이후에도 저수로 호안과 하상의 안정성이 유지되었으며, 이는 공법 설치 전 후 하상 경관의 변화가 거의 없어 수리적 안정성 유지를 하고 있다고 볼 수 있다. 또한 웅덩이 수제 공법 설치 후, 미소서식처가 형성되면서 포식자인 왜가리, 백로류를 지속적으로 관찰할 수 있어 어류서식처로서의 기능이 강화되었음을 간접적으로 확인하였다. 두 번째, 생태계 모니터링 결과 저서성 무척추동물의 경우 한국오수생물지수(KSI)는 낮은 바닥막이 공법을 적용하여 하상구조가 변화된 조사 지점 st.1의 환경상태가 "양호"에서 "최적"으로 변화하였기 때문에 공법 적용이 서식처 건강성 증진에 도움을 준 것으로 판단된다. 세 번째, 수질 모니터링 결과 용존산소의 경우 상부지점보다 하부지점이 낮게 나타나는 결과를 보여주었다. 낮은 바닥막이 공법에 의한 용존산소 상승효과보다는 다양한 서식처의 제공이라는 측면이 보다 중요한 효과를 나타낸다. 결과적으로, 공법의 실용화를 위한 적용 공법에 대한 생태계 모니터링 및 평가를 통하여 하천에서의 다양한 서식처(Habitat) 창출을 통해 수생 생물의 다양성을 증진시키고, 하천 하상공법에 대한 생태계의 조사 및 평가기법을 확보하여 연구성과를 다른 하천으로의 확대 적용 할 수 있을 것으로 기대한다.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.350-356
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• 2008

In this paper, we propose shading functions to the appropriate focused beamforming for near-field target estimation. This near field shading functions are based on Chebychev and Manning windows. In order to obtain the optimum sensor weighting values with the help of the proposed shading technique, we assume that the sensor positions associated to the non-uniformly distributed array are precisely known. We calculate a series of sensor weighting values from the FFT operation of given shading functions in time domain. By applying the shading weights on the sensor array, we can see that the level of sidelobe becomes diminished and the performance of estimating range and azimuth gets improved. In addition, we propose a non-uniform structure in terms of frequency bands, which may minimize the attenuation of incoming signals.

• Journal of the Economic Geographical Society of Korea
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• v.16 no.2
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• pp.218-232
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• 2013

One of the most interesting points in the era of globalization and transnationalism is the movement of people, namely migration. This research aims to explain the discourse of marginalization on Korean-Chinese by Korean merchants as the migrants expand their shops in the Chinese Food Culture Street. The Chinese Food Culture Street has been formed by Korean-Chinese restaurants and shops for the process of differentiation from the Garibong-Daelim area. Korean merchants in the street are not opposed to the influx of Korean-Chinese into Korea, however they do not want to the influx of them into the Jayang area. As the influx of Korean-Chinese into this street has increased, so the Korean merchants in the street have marginalized them as dangerous element for local security, as immoral beings cling to their business, and as the main reason for the regional underdevelopment. However, this marginalization of Korean-Chinese makes difficult to understand the real change of local area, because there has been some positive effects by the influx of them such as the improvement of surrounding environment and the elevation of local imagination. This research clearly suggest that the marginalization of migrants by major society is from the fixed idea and prejudice, and this research suggest the need to further study on the occupation and change of local by migrants.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.352-359
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• 2010

Stability of twin tunnels depends on the pillar width and the ground condition. In this study, large scale model tests were conducted for investigating the influence of the pillar width of twin tunnels on their behavior in the regular horizontal jointed rock mass. Jointed rocks was composed of concrete blocks. Pillar width of twin tunnels varied in 0.29D, 0.59D, 0.88D and 1.18D, where D is the tunnel width. During the test, pillar stress, lining stress, tunnel distortion, and ground displacement were measured. Lateral earth pressure coefficient was kept in a constant value 1.0. As a result, it was found that the pillar stress and the displacement of the ground and tunnel were increased by decreasing pillar width. The maximum displacement rate was measured just after the upper excavation in each construction sequence. And the maximum influence position was the right shoulder of the preceeding tunnel at the pillar side. It was also found that for the stability assessment the inner displacement was more critical than the crown displacement. The influence zone was formed at the pillar width 0.59D~0.88D that was smaller than 0.8D~2.0D, which was proposed by experience for a good ground condition. And it would be concluded that horizontal joints could also influence on the stability of the twin tunnels.

• Korean Journal of Heritage: History & Science
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• v.42 no.4
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• pp.132-151
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• 2009

Gut (Shaman ritual) in the west coast area is consisted to sanyang-geori (hunting), tasal-geori, gunwoong-geori those describe from hunting process to preparing animal sacrifices to a deity. The characteristic of gut in the west coast area which are represented for mock hunting and animal sacrifice ritual is practicing at the sibamasturi in Japan. This paper aims to compare a shaman ritual in west coast area in Korea and Japanese Sibamasturi from the comparative folklore point of view. Gut in the west coast area is well known for dividing sacrificial offering: vegetable for sinryeong and meat for singyeong. This division of spiritual deity shows it has different background from agriculture and hunting culture. Hwanghae-do gut has been formed under the various life environments. Therefore, each stage is conducted according to the purpose of the ritual. Sanyang-geori (hunting) represents the scene of hunting in the mountain and by catching live animals and it refers to Gunwoonsin, and will be offered. Animal sacrifice is a positive ritual which get rid of bad luck and pleased deity. Sibamasturi is practiced in mountain area where most of people involve in hunting and agriculture. Therefore, this area has both agricultural ritual and hunting ritual. Sibamasturi is practiced in January (lunar) and it also has meaning of beginning of agriculture and hunting in mountain area. Ground burnt off for cultivation way symbolizesfire ritual and mock hunting as well as animal sacrifice together. These rituals match to farmers of mountain area in the south-east Asia. The gut in the west coast area and Japanese Sibamasturi have common point that mock hunting and animal sacrifice are practiced at both rituals, however, the structure for these two ritual are different. In other word, there animal sacrifice has been formed with different cultural back ground.

• Journal of the Korean association of regional geographers
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• v.16 no.1
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• pp.59-75
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• 2010

This study analyzed on the recognition characteristics of high school students in Seoul about the factors influencing the land value. The results are as follows; First, when the factors influencing the land value was divided into 'the factors related with the publicly assessed land value' and 'the unrelated factors.' Students recognized that the former had more influence on the land value than the latter. Second, students recognized that 'the relative factors of land' had more influence on the land value than 'the absolute factors of land'. Third, as a result of checking how much five evaluation criterions influence on the recognition characteristics about the factors influencing the land value, the distance to major facilities had the most influence on the recognition, while the situation of land use had the weakest one. Among 13 factors, the distance from the convenience facilities was most influential and the shape of the land was least influential. Fourth, there was a gap between recognition of choosing the highest land value areas and the lowest land value areas and recognition of degree that the factor influencing the land value had an effect on the land value. Lastly, when the result of recognition about factors influencing the land value and the land value ranking was compared with the result of the co-relation between the land value and factors influencing the land value of the real region, either similar or different results were shown.