• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.480-485
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• 2004

If a wall separates the bounded and unbounded spaces, then the wall's role in transporting the acoustic characteristics of the two spaces is not well defined. In this paper, we attempted to see how the acoustic characteristical of two spaces are really affected by the spatial characteristics of the wall. In order to understand coupling mechanism, we choose a finite space and a semi-infinite space separated by the flexible or rigid wall and an opening. A volume interaction can be occurred in structure boundary and a pressure interaction can be happened in the opening boundary. For its simplicity, without loosing generality, we use rather simplified rectangle model instead of generally shaped model. The source impedance is presented to the various types of boundaries. The distributions of pressure and active intensity are also presented at the cavity and structure-dominated modes. The resulting modification, shifts of mode1 frequencies and changing of standing wave patterns to satisfy both coupled boundary conditions and governing equations, are presented.

• 한국멀티미디어학회논문지
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• 제16권4호
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• pp.444-452
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• 2013

Operation time of a function or procedure is a thing that always needs to be optimized. Parallelizing the operation is the general method to reduce the operation time of the function. One of the most powerful parallelizing methods is using GPU. In image processing field, one of the most commonly used operations is morphology operation. Three types of morphology operations kernel, na$\ddot{i}$ve, global and shared, are presented in this paper. All kernels are made using CUDA and work parallel on GPU. Four morphology operations (erosion, dilation, opening, and closing) using square structuring element are tested on MRI images with different size to measure the speedup of the GPU implementation over CPU implementation. The results show that the speedup of dilation is similar for all kernels. However, on erosion, opening, and closing, shared kernel works faster than other kernels.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2002년도 춘계종합학술대회
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• pp.407-410
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• 2002

미국, 독일, 영국 둥 주요 선진국에서는 시내망 경쟁활성화 및 사업자간 중복투자 방지를 위하여 가입자선로 세분화(Local Loop Unbundling: LLU)를 도입하고 있다. 광케이블 개방은 동선 가입자망의 개방과 함께 설비제공 대상의 주요 이슈가 되고 있다. 이 논문에서는 주요국의 광케이블 제공사례를 검토하여 시사점을 도출하고자 한다.

• KIEAE Journal
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• 제9권6호
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• pp.51-56
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• 2009

The most important advantages of atrium buildings are to allow the abundant natural lighting and outside views. However, the abundant lighting frequently causes to increase a cooling load in summer. The roof watering systems are useful to reduce the cooling load and save the energy. This study aims to investigate the effects of the roof watering system in atrium through the scaled model experiments. For the study, the 1/20 scaled model was made and tests were performed under the clear sky conditions through August 24 to september 7 in 2008. The model size was $45{\times}45{\times}60(cm)$ and depth of roof water was 3(cm). As results, the thermal effects of two types of atrium(roof opening, and roof and front opening,) were evaluated through the experimental points and conditions. It is expected to use the results for the next research to develop the practical roof watering systems for atrium.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권4호
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• pp.360-374
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• 2016

The present paper studies the ultimate torsional strength of stiffened box girders with large deck opening due to the influence of cracks. Three types of hull girders with different spans are provided for comparison. Potential parameters which may have effects on the torsional strength including the mesh refinement, initial deflection, material strain hardening, geometric properties of crack and stiffener are discussed. Two new concepts that play an significant role in the ultimate strength research of damaged box girders are introduced, one of which is the effective residual section (ERS), the other is the initial damage of the failure zone (IDFZ) for intact structures. New simple formulas for predicting the residual ultimate torsional strength of cracked stiffened box girders are derived on the basis of the two new concepts.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.788-790
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• 2004

This paper describes the phenomenon of the molten metal bridge theory of the arc discharge at opening contacts. And we analyze the magnetic force and drag force acting on the arc column in the DC magnetic contactor Arc cooling time by the force convection is calculated in the thermal dynamic equation using mean temperature method. Since arc gas lost conduction characteristics below a such temperature, it verify that the process of forming and extinguishing arc is able to analyze in terms of temperature characteristic by simulation and experiments of the 3 types arc extinction unit. It propose the practical simulation method to improve the electrical endurance of dc contactor.

• Structural Engineering and Mechanics
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• 제7권3호
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• pp.289-302
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• 1999

An approximate method for analyzing the bending problems of irregular-shaped plates is proposed. In this paper irregular-shaped plates are such plates as plate with opening, circular plate, semi-circular plate, elliptic plate, triangular plate, skew plate, rhombic plate, trapezoidal plate or the other polygonal plates which are not uniform rectangular plates. It is shown that these irregular-shaped plates can be considered finally as a kind of rectangular plates with non-uniform thickness. An opening in a plate can be considered as an extremely thin part of the plate, and a non-rectangular plate can be translated into a circumscribed rectangular plate whose additional parts are extremely thin or thick according to the boundary conditions of the original plate. Therefore any irregular-shaped plate can be replaced by the equivalent rectangular plate with non-uniform thickness. For various types of irregular-shaped plates the convergency and accuracy of numerical solution by proposed method are investigated.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2669-2681
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• 2021

Valve is widely used in the various industry areas to adjust and control the flow. Cavitation frequently takes place and sometimes is inevitable in various types of valve to cause the erosion damage. Therefore, how to control and minimize the effect of cavitation is still an important topic. This study numerically investigates the cavitating flow in a control valve with a perforated cage. The effects of some parameters on the cavitation are discussed. It also discusses to use the throttling steps to govern the cavitating flow. The results show that the opening degree of valve and the length of downstream divergent connection both influence the cavitation. The increase of the divergent length reinforces the cavitation. And the larger the opening of valve is, the intenser the cavitation is and the more vapor is present. The more throttling steps are helpful to decrease the cavitation.

• 대한치과보철학회지
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• 제45권2호
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• pp.240-249
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• 2007

Statement of problem: A phenomenon of screw-loosening in implant abutment is frequently occurred in a single and multiple implant restoration. Purpose: This study was performed to evaluate an effect of abutment material on screw-loosening before and after a cyclic loading. In a single-tooth implant, different materials of abutment, Type III Gold alloy and Zirconium composite$(ZrO_2/Al_2O_3)$ were used. Material and method: The Gold alloy(Type III) and Zirconium composite$(ZrO_2/Al_2O_3)$ were used to make a superstructure of implant, the one of types of UCLA, Each group was constituted of 5 sample with a 30-degree offset angulated loading platform. The external hexagonal fixture was rigidly hel d in a special holding zig to ensure solid fixation without rotation during the tightening and a cyclic loading. A Titanium-alloy screw was used to connect and controlled to be tighten in 20Ncm torque by a digital torque gauge. A 20 times of consecutive closing/opening cycle were performed to evaluate the immediate torque loss. In 5 sample of each material group, an initial opening torque was recorded during 3 closing/opening cycle, then 2Hz, 200N, 1,000,000 cyclic loadings were performed, then a opening torque was evaluated. Result & Conclusion: 1. In this limited study, titanium alloy screw tightened in 20Ncm, a cold-welding phenomen on was not observed during the 20 times of closing/opening cycle(p=0.11, p=0.18). 2. In titanium alloy abutment screw, repeated opening and closing of the screw caused to progressive decrease of opening torque(p=0.014). 3. The difference in preload of screw between gold alloy abutment and ceramic$(ZrO_2/Al_2O_3)$ abutment was not significant(p=0.78). 4. The difference in torque loss of screw between gold alloy abutment and ceramic$(ZrO_2/Al_2O_3)$ abutment was not significant after 2Hz,200N, 1,000,000 cyclic loading(p=0.92). 5. In titanium alloy abutment screw tightened by 20Ncm, the screw loosening was not significant on each group after 2Hz, 200Ncm, 1,000,000 cyclic loading(p=0.59).

• International journal of advanced smart convergence
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• 제9권1호
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• pp.154-162
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• 2020

We studies show that ratio of corpse among cremated bodies in public cremation facilities in metropolitan cities using E-Haneul funeral information system is average 90.1%, which is high, in bigger metropolitan cities with over 2 million of population (Incheon, Busan, and Daegu), but is average 81.4%, which is relatively low, in smaller metropolitan cities with less than 2 million of population(Daejeon, Gwangju, and Ulsan). In addition, the cremated bodies ratio of opening remains is average 17.4% in smaller metropolitan cities with less than 2 million of population, but is average 8.9% in those with over 2 million of population, which is relatively low. Finally, the cremated bodies ratio of dead fetuses is average 1.2% in smaller metropolitan cities with less than 2 million of population, and average 1.0% in those with over 2 million of population, which is low. Based on the above result, we are the following suggestions to improve the effectiveness of funeral facility use by the increase of demand for public cremation facilities in metropolitan cities. First, Busan and Daegu, where the shortage of supply is expected due to the increase of demand for cremation of corpse, need to implement supply expansion policy of public cremation facilities to build or expand cremation furnaces. Second, Daejeon, Gwangju, and Ulsan, where the cremated bodies ratio of corpse is low, need to expand supply through expanded operation from existing 4~8 cremation numbers of public cremation facilities to 11 cremation numbers, which is the level of Seoul Metropolitan City. Third, there should be cremation furnaces exclusively for opening remains to prepare the increase of demand for opening remains in the years with leap month.