• Journal of the Korean Geotechnical Society
• /
• v.20 no.8
• /
• pp.135-145
• /
• 2004

In this study, the behavior of unpropped diaphragm walls on decomposed granite soil was investigated through centrifugal and numerical modelling. Centrifuge model tests were performed by changing the interval distance of surcharge. Excavation was simulated during the centrifuge tests by operating a solenoid valve that allowed the zinc chloride solution to drain from the excavation. In these tests, ground deformation, wall displacement and bending moment induced by excavation were measured. FLAC program which can be able to apply far most geotechnical problems was used in the numerical analysis. In numerical simulation, Mohr-Coulomb model fur the ground model, an elastic model for diaphragm wall were used for two dimensional plane strain condition. From the results of model tests, failure surface was straight line type, the ground of retained side inside failure line had downward displacement to the direction of the wall, and finally the failure was made by the rotation of the wall. The angle of failure line was about 67 ∼ 74$^{\circ}$, greater than calculated value. The locations of the maximum ground settlement obtained from model tests and analysis results are in good agreements. The displacement of wall and the change of the embedment depth is likely to have linear relationship.

• Journal of Radiation Protection and Research
• /
• v.9 no.2
• /
• pp.55-60
• /
• 1984

The optimum etching condition of allyl diglycol carbonate (CR-39) for detecting the 60 MeV N-ions was determined as $70^{\circ}C$, 20% NaOH for 130min, by considering the variations of track density and diameter. Under these conditions, the maximum detectable track density was $1.7{\times}10^7tr/cm^2$. Track densities were linearly increased with increase of the total charge of the incident 60 MeV N-ions. By considering the scattring of N-ions as the Rutherford elastic scattering of point source, the measured relative probability was well consistent with the calculated value. The detection efficiency of CR-39 was in the range of 54-41% for 60 MeV N-ions of 12 nC-100 nC.

• Journal of KIISE:Computer Systems and Theory
• /
• v.35 no.12
• /
• pp.540-551
• /
• 2008

Today's microprocessor designs are not free from temperature as well as power consumption. As processor technology scales down, an on-chip circuitry increases power density, which incurs excessive temperature (hotspot) problem. To tackle thermal problems cost-effectively, Dynamic Thermal Management (DTM) has been suggested: DTM techniques have benefits of thermal reliability and cooling cost. However, they require trade-off between thermal control and performance loss. This paper proposes a dual integer register file structure to minimize the performance degradation due to DTM invocations. In on-chip thermal control, the most important functional unit is an integer register file. It is the hotspot unit because of frequent read and write data accesses. The proposed dual integer register file migrates read data accesses by adding an extra register file, thus reduces per-unit dynamic power dissipation. As a result, the proposed structure completely eliminates localized hotspots in the integer register file, resulting in much less performance degradation by average 13.35% (maximum 18%) improvement compared to the conventional DTM architecture.

• Science of Emotion and Sensibility
• /
• v.17 no.2
• /
• pp.63-76
• /
• 2014

Although most behavioral reaction times (RTs) for cognitive tasks exhibit positively skewed distributions, the majority of studies primarily rely on a measure of central tendency (e.g. mean) which can cause misinterpretations of data's underlying property. The purpose of current study is to introduce procedures for describing characteristics of RT distributions, thereby effectively examine the influence of experimental manipulations. On the basis of assumption that RT distribution can be represented as a convolution of Gaussian and exponential variables, we fitted the ex-Gaussian function under a maximum-likelihood method. The ex-Gaussian function provides quantitative parameters of distributional properties and the probability density functions. Here we exemplified distributional analysis by using empirical RT data from two conventional visual search tasks, and attempted theoretical interpretation for setsize effect leading proportional mean RT delays. We believe that distributional RT analysis with a mathematical function beyond the central tendency estimates could provide insights into various theoretical and individual difference studies.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.2 no.3
• /
• pp.119-127
• /
• 1990

Wave directional spectrum estimation methods for irregular waves were considered in this study. Until now, the Longuet-Higgins Method (LHM) initiated by Longuet-Higgins et al. (1963) has been widely used, but resolutions of the estimation were found to be low. Kobune's Maximum Entropy Method (MEM) for the estimation of wave directional spectrum, bas-ed on the entropy Principle showed higher resolutions comparing with the LHM . If the wave directional spectrum is of Delta functions, the MEM is exact in its estimation. It was also found that for a unimodal spectrum, if the Mitsuyasu's spreading coefficient is above 5, the estimation resolutions were high. In bimodal spectrum, as the angle difference between the two peaks increased, the resolution improved. The energy seems to transfer to the smoother peak in the smoothing of peak's peakedness. LHM has a tendency to estimate bimodal spectrum as a unimodal spectrum ； thus, except for its computational speed, the resolution of LHM falls far below that of MEM.

• Applied Chemistry for Engineering
• /
• v.8 no.6
• /
• pp.1000-1005
• /
• 1997

The properties of ceramics by solid-state reaction with hydroxyapatite[$Ca_{10}(PO_4)_6(OH)_2$], which was isolated from tuna bone by wet milling process were investigated. The bulk density $2.93g/cm^3$ at $1350^{\circ}C$ was close to the calculated density $3.21g/cm^3$. On X-ray measurements, the major phases were identified as hydroxyapatite at below $1300^{\circ}C$, but the whitlockite [$Ca_3(PO_4)_2$] phases were appeared due to a decomposition of hydroxyapatite with temperature. The microstructures of sintering specimens were shown as small closed pores between grain boundaries. The mean bending strength of the sintered hydroxyapatite by solid-state reaction is about 58 MPa and this value is higher than that of the articular cartilage maximum strength, 40MPa.

• Korean Journal of Optics and Photonics
• /
• v.33 no.3
• /
• pp.113-121
• /
• 2022

We analyze the link availability of satellite-to-ground free-space optical (FSO) communication systems in South Korea. Using ten-year meteorological data for five major cities (Seoul, Busan, Daegu, Daejeon, and Gwangju), we theoretically predict the link availability from the power losses induced by absorption, scattering, aerosols, and scintillation in the atmospheric channel. For accurate but conservative estimation of the link availability determined by cloud cover, we propose a loss model based on the maximum value of cloud droplet concentration. The results show that the link availability ranges from 45% to 70% when a single ground station is placed in a major city in South Korea and a 20-dB link budget is allocated for atmospheric loss. However, the availabilities improve to 90% and 97% when 3- and 5-site diversities are employed, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.30 no.5
• /
• pp.485-492
• /
• 2012

Today, a digital airborne imaging sensor plays an important role in construction of the numerous National Spatial Data Infrastructure. However, an appropriate quality assesment procedure for the acquired digital images should be preceded to make them useful data with high precision and reliability. A lot of studies therefore have been conducted in attempt to assess quality of digital images at home and abroad. In this regard, many test fields have been already established and operated to calibrate digital photogrammetric airborne imaging systems in Europe and America. These test fields contain not only GCPs(Ground Control Points) to test geometric performance of a digital camera but also various types of targets to evaluate its spatial and radiometric resolution. The purpose of this paper is to present a method to verify the spatial resolution of the Intergraph DMC digital camera and its results based on an experimental field testing. In field test, a simple bar target to be easily identified in image is used to check the spatial resolution. Images, theoretically designed to 12cm GSD(Ground Sample Distance), were used to calculate the actual resolution for all sub-images and virtual images in flight direction as well as in cross flight direction. The results showed that the actual image resolution was about 0.6cm worse than theoretically expected resolution. In addition, the greatest difference of 1.5cm between them was found in the image of block edge.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.5
• /
• pp.55-60
• /
• 2017

It is critical for Korea to make effective use of limited space as it has dense population and high traffic volume compared to its terrestrial area. To resolve this issue, diverse types of underground structures have increasingly been applied so far, and one of the most representative structures is double-deck tunnel. It has upper and lower roads separated by middle slab that shows dynamic behavior according to the vehicle and earthquake loads. In case of the characteristics of earthquake response, it is necessary to have exploratory study as it has high loads, complex working mechanism, and difficult theoretical approach. In order to understand the characteristics of earthquake response based on the supporting conditions of middle slab in double-deck tunnel, this study conducts indoor shaking table test with 3 test cases: (1) fix both brackets, (2) free and fix at each bracket and (3) free at both brackets for 2 seismic waves of artificial and Gyeongju earthquake. The result shows if the middle slab is free at both brackets, the acceleration response is reduced 41% for artificial earthquake and 60% for Gyeongju earthquake compared to the one with fix at both brackets.

• 전기의세계
• /
• v.24 no.4
• /
• pp.6-10
• /
• 1975

반도체와 그의 응용소자는 지난 20여년간 눈부식 발전을 이룩하였다. 이는 주로 단결정의 제작기술 진보에 의한 것으로 본다. 그러나 최근 단결정과는 전연 다른 유리질반도체가 국제회의에서도 그 우수성을 의논하기에 이르렀다. 유리질 반도체가 주목을 끌게 된겻은 1968년 Ovshinsky가 "무질서 구조에 있어서 가역적 스위칭현상"이라는 논문이 발표되고 유리질 반도체를 사용한 Ovonic 스위칭 소자의 출현에 기인된다. 유리질 반도체가 전기스위칭 작용, 기억작용을 나타낸다고 하는 Ovshinsky의 발표는 전자제치로서의 응용에 대해 찬반되는 의견이 있었지만 물성적 연구의 교량적인 역할을했다고 할 수 있다. 이런 반도체에 속하는 재료는 호칭도 여러가지로 유리질반도체, 비정질반도체 무정형반도체등으로 불리어진다. 단결정체가 각 격자간에 장거리질서를 갖는 반면 유리질 반도체는 무질서한 구조로 각 격자간에 단거리 질서를 갖는 것이 단결정과는 본질적으로 다른 점이라 본다. 유리 반도체의 종류는 첫째, 원소성 유리반도체로서 Ge, Si, Se, Te 들과 같이 단일원소로 된 겻과, 둘째 IV, V, VI족 원소로 된 공유결합 합금인 As$_{2}$Se$_{3}$-As$_{2}$Te$_{3}$ 계 Ge Si As Te계등의 칼코게나이드 유리등으로 금지대는 어느 것이나 2eV이하이다. 셋째 이론결합인 SiO $Al_{2}$O$_{3}$ Ta$_{2}$O$_{3}$Si$_{3}$N$_{4}$등의 산화물 및 질화물로 대표되는 분자성 비정질 물질로서 금지대는 2eV보다 큰 세종류로 크게 분류할 수 있다. 분류할 수 있다. 한다. 단 개개의 문제에 관한 구체적인 해석 또는 검토에 관하여는 다음 기회에 미루기로하고, 우선 여기서는 당면문제로서 대처하지 않으면 안될 자동주파수제어문제및 계통의 경제운용문제만에 한정하여, 이것을 우리나라의 현상과 관련시켜 개설하고, 이들의 자동화에 관한 기본적인 문제를 간단히 적어 보겠다. 가능하다. 제작완료된 ASIC은 기능시험을 완료했으며 실제 line-of-sight(LOS) 시스템 구현에 적용중이다. 시대를 살아 갈 회원들이다. '컨텐츠의 시대'가 개막되는 것이며, 신세기통신과 SK텔레콤은 선의의 경쟁 과 협력을 통해 이동인터넷 서비스의 컨텐츠를 개발해 나가게 될 것이다. 3배가 높았다. 효소 활성에 필수적인 물의 양에 따른 DIAION WA30의 라세미화 효율에 관하여 실험한 결과, 물의 양이 증가할수록 그 효율은 감소하였다. DIAION WA30을 라세미화 촉매로 사용하여 아이소옥탄 내에서 라세믹 나프록센 2,2,2-트리플로로에틸 씨오에스터의 효소적 DKR 반응을 수행해 보았다. 그 결과 DIAION WA30을 사용하지 않은 경우에 비해 반응 전환율과 생성물의 광학 순도는 급격히 향상되었다. 전통적 광학분할 반응의 최대 50%라는 전환율의 제한이 본 연구에서 찾은 DIAION WA30을 첨가함으로써 성공적으로 극복되었다. 또한 고체 염기촉매인 DIAION WA30의 사용은 라세미화 촉매의 회수 및 재사용이 가능하게 해준다.해준다.다. TN5 세포주를 0.2 L 규모 (1 L spinner flask)oJl에서 세포간의 응집현상 없이 부유배양에 적응,배양시킨 후 세포성장 시기에 따른 발현을 조사한 결과 1 MOI의 감염조건 하에서는 $0.6\times10^6$cell/mL의 early exponential시기의 세포밀도에서 72시간 배양하였을 대 최대 발현양을