• Journal of Ubiquitous Convergence Technology
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• 제2권2호
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• pp.97-104
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• 2008

In this paper, we demonstrate the boundary effect of a deployed regions on the effective coverage of a mobile node. A node coverage area is not uniform throughout the entire deployed region. Assuming a uniform coverage can result in significant error in calculations. In this study, we analyze the behavior of a node's coverage area as a function of its transmission range throughout the entire deployed region. Using this analysis, a mathematical model for effective coverage in mobile wireless communications is created. The mathematical model considers the effect of the deployed regions boundaries on the coverage area of a mobile node. Lastly, we present simulation results to verify the analytical model and to compare this model with that of a uniform coverage.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.117-124
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• 2007

The pressure ripple in most hydraulic systems is the root cause of their noise and vibration. This paper reduced the pressure ripple using side branch hose for an axial piston pump applied to small excavator. First, in calculating open area, a new method using groove area of valve plate is proposed. Simulation model in AMESim environment is developed to verify proposed method, find effective length and diameter of branch hose. Finally, the comparisons with experiment results show that the proposed method is more effective than previous method in reducing the pressure ripple.

• Journal of Information Technology Applications and Management
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• 제13권2호
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• pp.87-97
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• 2006

Due to limited radio resource, an effective paging strategy is essential for improving the utility of radio channels. In current mobile communication networks, when a mobile-terminated call occurs, the network locates the mobile by paging all cells within the location area simultaneously. In this study, we introduces paging strategies that can page some cells or only one cell within the location area to reduce paging cost on radio channels using paging agents. We propose another new paging strategy that can page only one cell within the location area and may have better performance. We also compare the performance of our proposed paging strategy with the performance of the current simultaneous paging strategy and some new paging strategies using paging agents. This paper suggests the most effective paging strategy using mathematical models. The result of this research will be used to select a proper paging strategy in the mobile communication networks.

• 대한안전경영과학회지
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• 제23권4호
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• pp.43-48
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• 2021

In this study, the experiment was conducted on a fire door(W × H = 0.98 m × 2.19 m) installed on the vestibule. The effective leakage area for each opening angles and closing forces derived from the impulse-momentum equation was compared and analyzed with the experimental results. As a result of the experiment, the major factors affecting the door closing forces were the pressure difference and the area of the door. The difference of door closing forces between measured and calculated values by the impulse-momentum equation showed a deviation of less than ±15% at the opening angles of 5°to 10°. At the door opening angle of 2.5°, the dynamic pressure was much higher than the measured static pressure, and this pressure difference is estimated to be air resistance acting to prevent the door from being completely closed.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.157-160
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• 2008

This study analyzed on the area of Samcheok, Kangwondo about forest fire alarming area and enlargement of the area. Then, visible area by unattended watching camera and watchtower for forest fire which were run by Samcheok was cross-checked with geographic information system, and it could be whether effective on watching the area where the forest fire risk was high enough and also it could be expanded to larger forest fire. The result of study, the visible area by watching facilities only holds for 13.4% of the whole forest fire alarming area, but the forest fire can be observed even though it is occurred in small valley because of smoke and all the forest fire have been occurred in daytime. Therefore, it can be determined that watching area will be extended around 50.3% while the observation radii of watching facilities raise by 4km. However, Samcheok has much greater area of mountain area in compared to any other cities or counties, watching facilities should be installed and run additionally for extinguishing the forest fire from the beginning.

• 대한지리학회지
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• 제42권6호
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• pp.940-954
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• 2007

본 연구에서는 전국에 분포되어 있는 18,060개의 농업용저수지의 기본적인 제원을 분석하여, 그 평균적인 특성을 파악하는 것을 목적으로 한다. 이러한 특성들은 외국의 저수지 특성과도 비교하였다. 저수지의 특성으로 고려한 허가면적, 수혜면적, 유효저수량, 만수면적, 제당길이, 제당높이의 총 7가지 항목에 대하여 히스토그램을 작성하여 분포특성을 확인하였으며, 멱승법칙(power law)을 이용하는 파레토 분석을 통해 저수지 분포의 불평등성을 파악하였다. 히스토그램 분석을 통해서는 댐(즉, 하천의 단면)의 특성을 나타내는 항목들은 대수정규분포와 유사한 형태로 나타났으며, 반대로 유역의 특성을 나타내는 항목들은 지수분포를 따르는 것으로 파악되었다. 파레토 분석은 지수분포형을 나타내는 5가지의 항목들에 대하여 수행하였다. 추정된 파레토 지수는 허가면적의 경우는 0.38, 수혜면적은 0.42, 유효저수량은 -0.19, 유역면적은 0.30, 만수면적은 0.22로 수혜면적의 경우가 불평등성이 가장 크고 반대로 유효저수량의 경우가 불평등성이 가장 작은 것으로 파악되었다. 저수지의 형상지수와 저수지면적과의 관계를 분석한 결과 한국의 농업용 저수지는 대부분 깊은 또는 보통 자지로 분류됨을 알 수 있었다. 이러한 특성은 기존연구를 통해 살펴본 외국의 저수지와도 유사한 것으로 파악되었다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2003년도 추계학술발표회 논문집
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• pp.237-242
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• 2003

During the past, digital orthophoto is generated for rural area or low resolution image, because the accurate extraction of DEM is difficult for urban area. But, nowadays, high resolution DEM by ALS system starts to become available for urban area, so the importance of large scale digital orthophoto generation becomes increasing. In this paper, we propose and describe effective algorithm for detecting occlusion area and not only restoring occlusion area but also processing null pixels by occlusion area for minimizing the heterogeneity of digital orthophoto. With proposed algorithm, we detected occlusion area due to height of structures such as buildings, bridges, etc, and restored occlusion area using reference image. Also, The homogeneity of generated digital orthophoto was improved by using brightness correction.

• 한국조경학회지
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• 제33권2호
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• pp.83-91
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• 2005

The purpose of this study is to analyze the arrangement of parks, in whole city level by using park's effective distance and to find the accessibility obstacles in case of using parks, in boundary of each parks' effective distance, so that to show how to improve communities' usage of city parks. The 8 cities in Gyeonggi-do and analysed the effective distance of parks. To find the accessibility obstacles in the boundary of parks' effective distance, 1) we choose 18 sample parks and extract obstacles - wide road, rail road, river- in interior and verify it by field survey and asking the park user's residents directly. The main findings of this study can be summarized as follows: First, Ansan city and Goyang city are only satisfied with the minimal city parks size standard, so that the rest 6 cities are lack of quantities which residents can use. The result of analyzing effective distance in whole city level, parks are mainly designated in new-town, so that most cities which have old-towns have very poor park systems to use. Because Ansan city is new-planned city, it is very effective arrangement in park systems exceptionally. Second, $96.2\%$ of park users' are living in the area which was easy to gain access not intercepted by wide road, rail road or river. Third, therefore at the stage of planning park, effective distance and resident's accessibility as well as park's supply quantitatively are needed to be considered. In addition, selection of location and elevation of resident's safety and accessibility through making a plan must be reflected. In the low accessibility area, the program to improve park's accessibility and amenity - like making small park or pocket park, linking parks with resident-friendly road etc.- has to be investigated.

• 한국지반신소재학회논문집
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• 제9권1호
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• pp.1-11
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• 2010

본 연구에서는 대상지역에 대한 지질조건에 따른 토질특성을 조사하였다. 대상지역의 지질은 인곡응회암, 유치역암, 다도응회암 등으로 구분되며, 유치역암은 대상지역의 약 80%를 점유하고 있다. 대상지역에 주로 분포하고 있는 역암, 응회암 및 세일구간에 대하여 비교란 및 교란시료를 채취하고 각종 실내토질시험을 실시하였다. 역암지역의 경우 건조단위중량이 크고 투수계수가 작으며, 응회암 및 셰일 지역의 경우 건조단위중량이 작고 투수계수가 큼을 알 수 있다. 흙의 유효입경과 세립토함유량은 흙의 투수계수에 많은 영향을 미치고 있음을 알 수 있다. 즉, 흙의 유효입경이 증가함에 따라 흙의 투수계수는 증가하고, 흙의 세립토 함유량이 증가함에 따라 투수계수는 감소하게 된다.

• Journal of Korean Neurosurgical Society
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• 제64권2호
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• pp.261-270
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• 2021

Objective : Decompressive craniectomy (DC) can partially remove the unyielding skull vault and make affordable space for the expansion of swelling brain contents. The objective of this study was to compare clinical outcome according to DC surface area (DC area) and side. Methods : A total of 324 patients underwent different surgical methods (unilateral DC, 212 cases and bilateral DC, 112 cases) were included in this retrospective analysis. Their mean age was 53.4±16.6 years (median, 54 years). Neurological outcome (Glasgow outcome scale), ventricular intracranial pressure (ICP), and midline shift change (preoperative minus postoperative) were compared according to surgical methods and total DC area, DC surface removal rate (DC%) and side. Results : DC surgery was effective for ICP decrease (32.3±16.7 mmHg vs. 19.2±13.4 mmHg, p<0.001) and midline shift change (12.5±7.6 mm vs. 7.8±6.9 mm, p<0.001). The bilateral DC group showed larger total DC area (125.1±27.8 ㎠ for unilateral vs. 198.2±43.0 ㎠ for bilateral, p<0.001). Clinical outcomes were nonsignificant according to surgical side (favorable outcome, p=0.173 and mortality, p=0.470), significantly better when total DC area was over 160 ㎠ and DC% was 46% (p=0.020 and p=0.037, respectively). Conclusion : DC surgery is effective in decrease the elevated ICP, decrease the midline shift and improve the clinical outcome in massive brain swelling patient. Total DC area and removal rate was larger in bilateral DC than unilateral DC but clinical outcome was not influenced by DC side. DC area more than 160 ㎠ and DC surface removal rate more than 46% were more important than DC side.