• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1095-1104
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• 2013

The number of vehicles registered in Korea is rapidly increasing and will reach 18.26 million as of June 2011. The rapid increase of large-size passenger cars and RVs among this number is causing damage to other vehicles when parked in currently installed parking lots, increased civil complaints from the damage, and inconveniences to people trying to pass through parking lots as well. In particular, the car-stoppers indiscriminately installed at the parking lots are also causing accidents and adding to parking problems, causing economic losses. Accordingly, there should be new regulations for the amount of parking space per vehicle and for locations to install the car-stoppers. The research has first reviewed the distribution ratio of vehicle models from home and abroad for the width and length of the vehicles by each model, parking space per vehicle where the car-stoppers are installed and examples of changes in distribution ratio. In addition, the amount of parking space per vehicle was calculated with consideration for various specifications by each car model. As a result, margin width of full sized car is decreased by 18~21mm on the existing width. This is judged decreases accident of parking lot, because length of the front of car is not deviate parking Space Section. In conclusion, presented improvement ideas for parking plans with enhanced convenience and safety from the aspect of the drivers. Parking lot relevant businesses will also be maximized in terms of cost and efficiency when the criteria for the structure of parking lots and their installation is established and the improved parking plan is applied in the future.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.876-880
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• 2015

In 2016, the IMO's new rules for an 80% reduction in NOx emissions in newly built ships will necessitate the use of LNG as a clean fuel. So far, the developed European countries have led the development of LNG bunkering ships and related facilities. An LNG bunkering system stores LNG in a horizontal or vertical IMO "C"-Type tank insulated with perlite powder, and a vacuum in the annular space between the double walls, like the cryogenic liquid nitrogen tank. Current storage tanks have high heat leakage, evaporating over 2.0% daily, and are difficult to build with the required vacuum. A more efficiently insulated storage tank could reduce the evaporation rate. This research carried out thermal analysis on a new effective insulation method that separates high vacuum in the annular space between two tanks with a solid insulation material, such as urethane foam, lining the outer vessel. This highly efficient insulation system obtained an evaporation rate of 0.03% per day under a $10^{-3}torr$ vacuum, and an evaporation rate of 0.11% at $10^{-45}torr$. Even if the space loses its vacuum, the new insulation system showed a lower evaporation rate of 4.12% than the present perlite system of 4.9%. This newly developed tank can increase the efficiency of LNG storage tank and may help keep LNG bunkering systems safe.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.5
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• pp.485-501
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• 2012

This study aims to experimentally investigate ground settlement and ground movement around the square pipe by its penetration in sandy ground. A series of laboratory model tests were carried out with a small-scale auger equipment for penetration of a square pipe as well as a newly designed test box with a sand raining equipment. From the experiments, it is shown that a square pipe induces ground movement evenly around it in a low overburden condition. However, as the overburden becomes higher, ground movement by a square pipe is concentrated mainly above it. Especially, horizontal strain above the square pipe was mainly dominated by its penetration. In addition, sand surface movement is the smallest in case of the dimensionless penetration rate equal to 0.2. When its penetration rate of the square pipe is fixed, the rotation speed of auger controls surface movement whether it is settlement or heaving. Therefore, the selection of an optimal dimensionless rate for the square pipe is a key design factor to minimize ground settlement in a trenchless construction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.373-379
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• 2020

This study performed stress and fatigue life analysis of the damping hinge of a built-in side-by-side refrigerator that occurs when the door is opened to the maximum angle. An analysis of the initial design showed that stress concentration occurred at the corner between the cylinder and upper disk of the bracket pin, and the maximum stress exceeded the yield strength. The maximum stress location and the calculated fatigue life were consistent with the door opening-and-closing endurance test results for a prototype. Three cases of design improvement for the bracket pin were derived with the aim of reducing the stress concentration that appeared in the initial design. An analysis of the cases showed that inserting a fillet between the disk and the cylinder of the bracket pin reduced the stress and increased the fatigue life. Moreover, changing the disk into two steps was more favorable. In conclusion, the best design improvement was the case that the disk was changed to two steps and the fillet with a large radius was inserted. In that case, the stress was the smallest and the fatigue life was infinite.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.675-680
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• 2017

Considering that most sewage treatment facilities have a water head of less than 2.0 m and a constant flow rate, the development of a small hydro power generation device capable of maintaining stable power generation and efficiency is urgently needed. In this study, a numerical analysis using the CFD code was carried out to develop a drag force type vertical axis hydro turbine for the improvement of the production efficiency of small-scale hydro energy underlow flow velocity conditions. The blade pressure changes and internal flows were analyzed in the presence or absence of hydro turbine blade holes at a flow velocity of less than 2.0 m/s. The pressure distribution of the hydro turbine blades with holes was found to be about 5.1 % lower than that of the hydro turbine blades without holes. The analysis of the internal flow around the water tank and hydro turbine blade revealed that the flow velocity varied with the vector distribution and that the flow velocity of the hydro turbine blades with holes was 5.6 % less than that of the hydro turbine blades without holes. It is believed that forming a hole in the blade may be helpful for its structural safety.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.58-65
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• 2010

The final goal of our research is developing not a simple collision a1ann equipment for the blinded walkers, but the apparatus (Audio- Vision System) which can simulate vision based on auditory information so that the blinds can figure the three dimensional space in front of them. On the way to the final goal, in this study, simulation software was developed and verified. Thirty normal volunteers were included in the subject group and the average age Was 25.8 years old. After being accustomed to the system by evaluating 10 blinded virtual spaces, the volunteers performed test using another set of 10 blinded virtual spaces. The results of test were scored by shape, center, margin, and gradient surface of objects in virtual space. The score of each checking point ranged from 1 to 5, and the full score was converted to 100. As results of this study, the total score ranged from 77 to 97 with the average of 88.7. In this study, a simulation software was developed and verified to have acceptable success rale. By combining to visual sensors, the vision-reconstruction system based on auditory signal (Audio-vision System) may be developed.

• Journal of Navigation and Port Research
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• v.39 no.1
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• pp.69-75
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• 2015

The concrete purpose of this study is to suggest actually a debt ratio to optimize the capital structure providing a kind of approach to estimate the proper debt ratio with an analytical model and empirical data in Korean shipping industry. The mathematical and analytical model is started from the first equation about ROE, return of net operating income on equity, with an independent variable, debt ratio. It is constructed with several parameters, ROS(return of operating income on sales), TAT(total assets turnover), and NFCL(net finance cost to liabilities). There could not be a certain relationship between debt ratio and ROS or TAT, while some correlation or causality between debt ratio and NFCL. In other words, most of firms with high debt ratio is likely to burden higher finance cost than others with low one. In this case, there is a linearity relationship between debt ratio and NFCL, so then the second equation considering this relation could be included within the analytical approach of this paper. To be short, if the criteria of adequate debt ratio has to be defined as some level of debt ratio to optimize ROE, the ROE could be illustrated as a quadratic equation to debt ratio from two equations. Next, this research estimated those parameters' numbers through the single regression method with data over 12 years of Korean shipping industry, and identified empirically the fact that optimal debt ratio would be approximately 400%. To conclude, if that industry's sales and operating incomes are stable, the debt ratio could be accepted until twice of 200% had forced in order to guarantee its financial safety in past time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3C
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• pp.398-407
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• 2004

In this paper, a blind watermarking method which is suitable to the video compression using 2-D discrete wavelet transform was proposed and implemented into the hardware using VHDL(VHSIC Hardware Description Language). The goal of the proposed watermarking algorithm is the authentication about the manipulation of the watermark embedded image and the detection of the error positions. Considering the compressed video image, the proposed watermarking scheme is unrelated to the quantization and is able to concurrently embed or extract the watermark. We experimentally verified that the lowest frequency subband(LL4) is not sensitive to the change in the spatial domain, so LL4 subband was selected for the mark space. And the combination of the bitplanes which has the properties of both the minimum degradation of the image and the robustness was chosen as the embedded Point in the mark space in LL4 subband. Since we know the watermark embedded positions and the watermark is embedded by not varying the value but changing the value, the watermark can be extracted without the original image. Also, for the security when exposing the watermark embedded position, we embed the encrypted watermark by the block cipher. The proposed watermark algorithm shows the robustness against the general image manipulation and is easily transplanted into the image or video compressor with the minimal changing in the structure. The designed hardware has 4037 LABs(24％) and 85 ESBs(3％) in APEX20KC EP20K400CF672C7 FPGA of Altera and stably operates in 82MHz clock frequency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.246-251
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• 2016

The use of security lighting that emits spill light is considered a cause of light trespass problems in the residential areas. Therefore, a cutoff panel was installed as an alternative way to reduce light trespass. On the other hand, it has another problem in that it is less effective and is not good enough for aesthetics and safety. In this study, a light cutoff panel was designed and manufactured to reduce the light trespass, and the structure of a proper light cutoff panel was studied. Using a goniophotometer, the light distribution file (IES file) was extracted and the characteristics of light distribution were analyzed using the RELUX program. The results showed that the reduction of spilt light in the backward direction was decreased significantly for all types of light cutoff panels except the coated globe. In the case of a black powder coated light cutoff panel, the forward light caused by light reflected from the surface of the light cutoff panel was also reduced, which means that the black powder coated light cutoff panel is effective in the performance of light cutoff in the forward and backward directions. In addition, the coated glove increased the spilt light in the forward and backward directions because it reflects the upward light to go down. A 90 % accuracy between the measurement value of light trespass and the expected value of the light trespass was obtained from a simulation.

• Annual Conference of KIPS
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• 2000.10a
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• pp.677-680
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• 2000

웹이 등장하면서 지금까지 인터넷 상에서 텍스트와 이미지를 이용하여 정보를 표현하고 전달하는 방법이 가장 많이 사용되어왔다. 그러나 웹 관련 기술의 비약적인 발달과 네트워크 속도의 증가 및 인터넷의 급속한 보급으로 단순한 텍스트와 이미지 중심의 HTML 문서를 이용한 정보의 전달이 아닌 멀티미디어 데이터를 이용한 정보의 표현과 전달이 점차 증대되고 있다. 이에 따라 멀티미디어 데이터를 전송하기 위한 스트리밍 프로토콜도 등장하였다. 최근에는 컴퓨터의 성능 증가 및 네트워크 속도의 증가(초고속 통신 서비스의 보급)에 의해 멀티미디어 데이터의 전송이 가능하게됨으로써 기존의 공중파나 CATV 방송국의 형태 지니고 인터넷 상에서 실시간 생방송 서비스와 VOD(Video On Demand) 서비스를 제공하는 인터넷 방송국이 급속하게 생겨나고 있다.[11] 인터넷 방송은 동영상과 오디오의 실시간 전달을 가능하게 하는 멀티미디어 스트리밍 기술과 멀티미디어를 실시간으로 전송할 수 있는 실시간 전송 프로토콜을 기반으로 발전하고 있다. 인터넷 상에서 멀티미디어 스트리밍 서비스를 하는 대부분의 인터넷 방송은 스트리밍 서버로서 RealNetworks사의 RealSystem과 Microsoft사의 WMT(Windows Media Technologies)를 사용하고 있다. 본 논문은 Real Server와 WMT의 비교 분석을 통해 실시간 전송 프로토콜을 지원하고, 멀티미디어 스트리밍 기술을 지원하는 자바를 기반으로 한 분산 서버 구조의 스트리밍 서버, 서버간의 부하를 제어하는 미들웨어, 멀티미디어 스트림을 재생할 수 있는 클라이언트를 설계하고 구현한다. 방법에 대해서 자세히 살펴보고 실제 SQL Server 7.0 환경에서 구축된 공간 엔진 및 OLE DB 제공자 컴포넌트의 구현 예에 대하여 살펴볼 것이다. 혈액내방사선 조사량이 안전용량 범위(200rad)에 속하며 48시간 후 체내잔류량은 서양인과 큰 차이가 없었다.비출현의 소견을 보이는 악성종양 환자의 골 신티그람 53개중 44개 (83.0%)에서 척추 및 늑골에 미만성, 또는 다발성 침습이 관찰되었다. 또 골전이 부위를 두개골, 척추, 견대부, 늑골, 골반, 사지의 근위부 장골의 6개 부위로 나누어 분석할 경우 49개(92.5%)에서 3부위 이상에 전이가 발견되었고, 35개(66.0%)에서 4부위 이상에 전이가 발견되었으며, 5부위 이상, 6개 부위에 모두 전이가 발견된 것은 각각 20개 (37 7%), 11개(20.8%)이었다. 이상의 성적으로 보아 악성종양 환자의 골 신피그라피에서 신장 영상의 비출현은 종양의 광범위한 골전이를 간접적으로 시사하는 소견으로 생각된다. 여러 악성종양중 전립선암에서 신장 영상 비출현의 빈도가 가장 높았으며, 특히 위암에서 골전이 및 신장 영상 비출현의 빈도가 높음은 주목할 만한 것이라 하겠다.출한 결과 인,규소 증가와 자가영양성 미소플랑크톤(ANP)증가에 미치는 요인이 해안과 외해에서 동일하게 가장 큰 설명력을 보였다. N:P 비도 해안에서 36.4, 외해에서 32.6을 보이고 있어 인이 상당히 부족한 것으로 나타났다. 따라서 조사해역은 인이 식물플랑크톤 성장에 중요한 제한요인으로 작용하고 있다고 판단된다.의 회전. 전위력의 강도, 적용시점, 그리고 키, 체중등의 신체적 요인 등이 있으나 능숙한 기계사