• Proceedings of the KOSOMBE Conference
• /
• v.1997 no.05
• /
• pp.35-38
• /
• 1997

The interfacial bonding energy between laser surface treated HA layer and Ti alloy substrate was investigated using a mechanical push-out tester. The initial slope of shear-stress and reduced displacement curves, maximum interfacial bond strength and bonding energy were calculated from results of the push-out test. The calculated initial slpoes are 38 MPa for the Ti alloy(A), 65 MPa for the sandblast finished specimen(B), 95 MPa for the HA plasma spray coated specimen and 49 MPa for the laser surface treated specimen(D). The maximum interfacial bonding strength are 3 MPa for the A, 19 MPa for the B, 20 MPa for the C, 10 MPa for the D. The interfacial bonding energies are $3.3\times10^{-9}J/mm^2$ for the A, $15.5\times10^{-9}J/mm^2$ for the B, $15.6\times10^{-9}J/mm^2$ for the C and $18.3\times10^{-9}J/mm^2$ for the D. Microscopic observation shows that the breaking of the laser treated specimen had been occured through the boundary between HA layer and polymer resin, but the untreated specimen had been occured through the inside of HA coating layer.

• International Journal of Highway Engineering
• /
• v.7 no.4 s.26
• /
• pp.9-20
• /
• 2005

This study was carried out to select most efficient bonding methods of geogrid at the interface of old concrete pavement before placing asphalt overlay layer for reflection cracking retardation. Three bonding methods, a RSC-4 emulsified asphalt, a compound and an unsaturated polyester resin (UPR) were compared in this study. Three types of asphalt mixture (AC 60-80, RLDPE 8%, PG 76-22) and a dense-graded aggregate were used for overlay asphalt pavement. A reinforcing material which consists of a woven fabric underneath a glass fiber grid was used. An expedite test method which is for simulating mixed mode (mode I and II) fracture test was performed using a wheel tracker in laboratory. Cracking development by load repetition was measured as fatigue life (number of load cycle) and expansion of specimen body were measured for each test specimen. The results showed that UPR was the best and RSC-4 the next. But considering field applicability, RSC-4 was considered as an appropriate choice for bonding reinforcing material.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.6
• /
• pp.1679-1688
• /
• 1990

The method of nonlinear parameter estimation(NPE), which is a statistical and an inverse method, is used to estimate the thermal diffusivity of the porous insulation material. In order to apply the NPE method for measuring the thermal diffusivity, and algorithm for programing suitable to IBM personal computer is established, and is studied the statistical treatment of experimental data and theory of estimation. The experimental data obtained by discrete measurement using a constant heat flux technique are used to find the boundary conditions, initial conditions, and the thermal diffusivity, and then the final values are compared with the values obtained by some different methods. The results are presented as follows:(1) NPE method is used to establish the estimation of the thermal diffusivity and compared results with experimental output shows, that this method can be applicable to define the thermal diffusivity without considering hear flux types. (2) Because of all of the temperatures obtained by the discrete measurement on each steps of time are used to estimate the thermal diffusivity. Although some error in the temperature measurements of temperature are included in estimating process, its influences on the final value are minimzed in NPE method. (3) NPE method can reduce the experimental time including the time of data collecting in a few minutes and can take smaller specimen compared with steady state method. If the tube-type furnace is used, also the adjusting time of surrounding temperature can be reduced.

• Journal of Korea Multimedia Society
• /
• v.14 no.8
• /
• pp.981-991
• /
• 2011

MIP(Maximum Intensity Projection) is a volume rendering technique which is essential for the medical imaging system. MIP rendering based on the ray casting method produces high quality images but takes a long time. Our aim is improvement of the rendering speed using GPGPU(General-purpose computing on Graphic Process Unit) technique. In this paper, we present the ray casting algorithm based on CUDA(an acronym for Compute Unified Device Architecture) which is a programming language for GPGPU and we suggest new acceleration methods for CUDA. In detail, we propose the block based space leaping which skips unnecessary regions of volume data for CUDA, the bisection method which is a fast method to find a block edge, and the initial value estimation method which improves the probability of space leaping. Due to the proposed methods, we noticeably improve the rendering speed without image quality degradation.

• Proceedings of the Korean Society for Cognitive Science Conference
• /
• 2000.06a
• /
• pp.255-261
• /
• 2000

동사의 애매성 해소는 언어학의 여러 부문 중에서도 가장 실체가 불명확한 의미를 다루는 것이기 때문에 언어학뿐만 아니라 자연언어처리에 있어서도 가장 해결하기 어려운 문제 중에 하나이다. 애매성은 언어학에서 말하는 동음이의어와 다의어를 동시에 포괄하는 개념으로 정의된다. 단일어를 대상으로 한 이와 같은 분류는 비교적 명확한 반면 두 개의 언어 이상의 다국어를 대상으로 하는 기계번역용 사전과 같은 대역사전에 있어서는 동음이의어와 다의어의 구별은 경계가 불명확하여 의미에 기반한 대역어의 작성에 도움이 되지 않는다. 그 원인은 의미를 구성하는 세 가지 요소인 [실체], [개념], [표현]의 관점에서 [실체]와 [개념]은 어느 언어를 막론하고 보편적인 반면 [실체]와 [개념]을 최종적으로 실현하는 형태인 [표현]의 경우 각각의 언어에 따라 그 형태가 다르게 표출된다고 하는 사실 때문이다. [나무]라는 [실체]가 있다고 할 때 [나무]에 대한 [실체]와 [개념]은 언어를 초월해서 공통적이라고 할 수 있다. 한편 [개념]을 표현하는 실체인 [표현]은 언어에 따라 [namu](한국어_, [ki](일본어),[tree](영어) 등과 같이 언어에 따라 자의적으로 [개념]을 표현하고 있다. [namu], [ki], [tree]가 같은 뜻을 나타낸다고 인식할 수 있는 것은 [개념]이 같기 때문이지 이들 각각의 [표현]이 의미적 연관성을 갖고 있기 때문은 아니다. 지금까지 의미를 다루는 연구에서는 이와 같은 관점이 결여됨으로 인해 의미의 다양성을 정확히 파악하는 데 한계가 있었으며 애매성 해소에 관한 연구도 부분적 시도에 그친 면이 적지 않다. 본고에서는 다국어를 대상으로 한 대역사전의 구축에 있어서 다의어와 동음이의어에 대한 종래의 분류의 문제점을 지적하고 나아가 애매성 해소의 한 방법론으로 활발히 이용되고 있는 시소러스의 분류체계의 한계를 지적한다. 나아가 이의 해결책을 한국어와 일본어의 대역사전의 구축에서 얻어진 경험을 바탕으로 제시한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 1999.10a
• /
• pp.105-105
• /
• 1999

핵연료 피복관은 핵연료에서 방사성 핵분열생성물의 방출을 저지하는 가장 뚱요한 방어막인데, 현재 지르칼로이 4가 피복관의 재료로 사용되고 있다. 사용후 핵연료는 원자력발전소내 습식 저장조에 저장되고 있으나, 지속적인 관리와 장소확보의 용이 성으로 인해 건식 저장조를 사용하는 추세에 있다. 본 연구에선 건식 저장조에 장 기간 저장되는 핵연료 피복관에 주변 환경으로부터 오염될 수 있는 소금기나 기름 등이 지르칼로이의 공기중 산화에 미치는 영향의 존재를 밝히려 한다. 현재 고리 원자력발전소에서 사용중인 핵연료 피복관을 1cm정도 높이로 자르고, 피복관 표면 을 ASTM -G2-88 방법으로 처리한 후 산화실험을 수행하였다. 산화정도는 간헐적 (intermittent) 방법을 사용하여 시편의 무게를 측정하여 구하였으며, 산화온도는 $400-500^{\circ}C$로 하였다. 소금이 흡착이 된 경우, 산화 속도는 흡착이 안된 시편보다 가속되었으며, 거의 이차법칙을 따르고 있다. 산화막 위의 흡착물의 영향을 알아보기 위해, 지르칼로이를 $500^{\circ}C$ 수증기에 $5g/m^2$ 두께로 산화시킨 후, 다시 산화실험을 수행하였다. 사용한 흡착물은 LiF, NaF, KF, NaCI 이다. 흡착물들은 산화를 대체로 가속시켰으며, NaF, KF, NaCI 순으로 그 영향력이 컸다. 그러나, LiF는 산화에 전혀 영향을 미치지 않았다. SIMS를 사용하여 각 시편의 두께에 따른 흡착물의 분포 를 알아보았다. 음이온(CI, F)과 양이온(Na, Li, K)이 산화막과 금속 경계면까지 관 찰되었으며, 음이온과 양이온의 분포는 대게 동일하였다. LiF의 경우 산화막에서 이들의 농도가 급격히 떨어지고 있음을 알 수 있었다. 산화막 내에서 이들 흡착물의 확산이 산화속도 가속의 원인이며 이들 흡착물중 CI과 F는 산화막과 금속 겸계면 에서 새로 생성되는 산화막의 강도에 영향을 미쳐, 일찍 미세균열을 만들기 시작하여 산화를 가속시키는 것으로 판단된다.

• Economic and Environmental Geology
• /
• v.43 no.4
• /
• pp.349-358
• /
• 2010

For imaging complex subsurface structures such as salt dome, faults, thrust belt, and folds, seismic prestack reverse-time migration in depth domain is widely used, which is performed by the cross-correlation of shot-domain wavefield extrapolation with receiver-domain wavefield extrapolation. We apply the prestack reverse-time migration, which had been developed at KIGAM, to the seismic field data set of Block 5 in Jeju basin of Korea continental shelf in order to improve subsurface syncline stratigraphy image of the deep structures under the shot point 8km at the surface. We performed basic data processing for improving S/N ratio in the shot gathers, and constructed a velocity model from stack velocity which was calculated by the iterative velocity spectrum. The syncline structure of the stack image appears as disconnected interfaces due to the diffractions, but the result of the prestack migration shows that the syncline image is improved as seismic energy is concentrated on the geological interfaces.

• Geophysics and Geophysical Exploration
• /
• v.10 no.4
• /
• pp.345-352
• /
• 2007

Two-dimensional (2D) MT surveys near the Century mine in Australia have been performed with very far remote reference in Esashi, Japan (RR_ESS) as well as Gregory Downs (RR_GREG), which are roughly 6,400 km and 80 km apart from the survey area, respectively. Good quality of MT data could be obtained by remote reference processing with RR_GREG, while the coherency of magnetic fields between field sites and RR_ESS was not sufficient to be used as remote data. Both 2D and 3D inversion of 2D profile data represented the general geological structure beneath the survey area. The main target of the survey, Termite Range Fault, appeared as a boundary between a conductive block to the north and a resistive block to the south in the reconstructed resistivity section, and is inclined slightly to the north-east direction.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.3
• /
• pp.145-152
• /
• 1989

Volume phase diffraction grating is formed in 5${mu}m$ Agfa 8E75 photographic emulsion film using He-Ne laser. It is dependent on the chemical processing rather than materials themselves that high diffraction efficiency can obtained in silver halide emulsions. With potassium dichromate bleach and alcohol drying, overall efficiency of 71% (81% after allowing for reflection at the two surfaces) has been achieved at an exposure of 180${mu}J/cm^2.$ Dichromate cross-linkage and air void by rapid dehydration increase refractive index modulation depth. The grating is swollen, which is newly identified by Scanning Electronic Microscope(SEM) photography, and it causes on-Bragg at larger angle than the recording angle. It is pointed out that controlling the emulsion thickness has an important role as a potential source for high diffraction efficiency.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.10 no.3
• /
• pp.109-119
• /
• 1998

A horizontal tow-dimensional version of POM (Princeton Ocean Model) was modified in representing the bottom friction and the open boundary conditions. To simulate the flooding and drying of intertidal flats, a wetting-and-drying scheme was incorporated into the model. The model then was applied to the Chunsu Bay and its adjacent coastal water. Only the water movement due to tides, the dominant forcing in the study area, was considered. This presents the procedure and the results of model calibration and verification for the Chunsu Bay system. The model was calibrated, using the average tidal characteristics in Tide Tables, for the amplitudes and the phases of tidal waves throughout the modeling domain. Calibration results showed that the model gave a good reproduction of tidal waves. The calibrated model was verified using the time-series measurements of surface elevation and current velocity in the summer of 1995. The model reproduced the tides currents very well. calibration and verification results demonstrated that the model is capable of reproducing the tidal dynamics in the Chunsu Bay system.