• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.114-131
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• 1992

In the present work, a two-dimensional boundary-value problem for a large amplitude motion is treated as an initial-value problem by satisfying the exact body-boundary and nonlinear free-surface boundary conditions. The present nonlinear numerical scheme is similar to that described by Vinje and Brevig(1981) who utilized the Cauchy's theorem and assumed the periodicity in the horizontal coordinate. In the present thesis, however, the periodicity in the horizontal coordinate is not assumed. Thus the present method can treat more realistic problems, which allow radiating waves to infinities. In the present method of solution, the original infinite fluid domain, is divided into two subdomains ; ie the inner and outer subdomains which are a local nonlinear subdomain and the truncated infinite linear subdomain, respectively. By imposing an appropriate matching condition, the computation is carried out only in the inner domain which includes the body. Here we adopt the nonlinear scheme of Vinje & Brevig only in the inner domain and respresent the solution in the truncated infinite subdomains by distributing the time-dependent Green function on the matching boundaries. The matching condition is that the velocity potential and stream function are required to be continuous across the matching boundary. In the computations we used, if necessary, a regriding algorithm on the free surface which could give converged stable solutions successfully even for the breaking waves. In harmonic oscillation problem, each harmonic component and time-mean force are obtained by the Fourier transform of the computed forces in the time domain. The numerical calculations are made for the following problems. $\cdot$ Forced harmonic large-amplitude oscillation(${\omega}{\neq}0,\;U=0$) $\cdot$ Translation with a uniform speed(${\omega}=0,\;U{\neq}0$) The computed results are compared with available experimental data and other analytical results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.2
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• pp.156-162
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• 1995

A numerical method for a 2-D oil boom model considering the flexibility of skirt has been developed The neater is assumed rigid and the skirt is tensioned membrane having a point mass at its end The fluid motion is potential. The kinematic condition which demands the continuity of the displacement is imposed at the joint between the floater and the skirt. The dynamic condition for the point mass is imposed at the bottom end of the skirt. The numerical method is based on the Green's function method in the frame of linear potential theory. It finds it's solution simultaneously from the total system of three equations, integral equation, the equation of motion of the floater and the equilibrium equation of the deformation of the skirt. Integral equation is derived by applying the Green's theorem to radiation potential and Green's function. Proper descretization of those three equations leads to the system of a linear algebraic equation. Due to the flexibility of skirt the motion of floater can be diminished in some range of wave frequency and furthermore the mechanism of resonance of the oil boom can be changed. The motion responses of various oil booms have been compared varying the length of the skirt and the point mass. The numerical method has been validated indirectly from the good correspondence between the motion responses of the flexible skirt model and the rigid skirt model in low frequency limit.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.8
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• pp.554-561
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• 2006

In recent years, as SoC design research is actively conducted, a large number of IPs are included in a system. Various bus protocols and bus architectures are designed to increase IP reusability. Among them, the AMBA AHB became a de facto standard although it is somewhat inadequate for a large scale SoC. We proposed SNP and SNA, high performance on-chip-bus protocol and architecture, respectively, to solve the problem of the conventional shared buses. However, it seems to be imperative that the new on-chip-bus system support AMBA-compatible IPs for a while since there are a lot of IPs with AMBA interface. In this paper, we propose an extended SNP specification and a corresponding SNA component to support ABMA-compatible IPs used in SNA - based system. We extend the phase of the SNP by 1 bit to add new 8 phases to support communication based on AMBA protocol without penalty of elongated cycle latency. The ARB-to -XSNP converter translates the protocol between AHB and SNP to attach AMBA -compatible IPs to SNA based system. We show that AMBA IPs can communicate through SNP without any degradation of performance using the extended SNP and AHB - to- XSNP converter.

• The Journal of the Korea Contents Association
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• v.20 no.3
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• pp.245-253
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• 2020

If the conversion rate of jeonse price to monthly rent is the market interest rate or the landlord's expected return, then the conversion rate of jeonse price to monthly rent in the country should be the same. However, the conversion rate of jeonse price to monthly rent has always been higher than the market interest rate. This study identifies the supply cost components of rental housing as a risk premium in the presence of current housing prices, market interest rates, depreciation costs, holding taxes, and leases, and identifies the relationship between the current housing prices and each factor. Housing rent is expressed as the current price. This overcomes the shortcomings that implicitly assume fluctuations in housing prices or do not include current housing prices in the conversion rate of jeonse price to monthly rent. This study found that the conversion rate of jeonse price to monthly rent is the required rate of return or required rate of renter, not market interest rate, by expressing the supply cost of rental housing as a combination of components. This not only explained the fact that the conversion rate of jeonse price to monthly rent was always higher than the market interest rate, but also explained the regional differences. It also explained why the conversion rate of jeonse price to monthly rent varies by type of housing.

• The Journal of Korean Medicine
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• v.19 no.1
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• pp.89-99
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• 1998

약효(藥效) 및 안정성(安定性)이 입증(立證)된 한약(韓藥)으로부터 새로운 항균제(抗菌劑)를 도출(導出)하고자, 임상(臨床)에서 청열작용(淸熱作用)이 있거나 염증성(炎症性) 질환(疾患)과 박테리아의 감염(感染)으로 비롯된 질환(疾患)에 자주 쓰이는 22개(個)의 처방(處方)에 대(對)해 paper disk 법(法)을 사용(使用)하여 항균(抗菌) 효능(效能)을 검색(檢索)하였다. 시료(試料)는 한약(韓藥)의 고용(股用) 방법(方法)을 고려(考慮)하여 물로 추출(抽出)하였으며, 사용(使用) 균주(菌柱)로는 그람 양성균(陽性菌)인 포도상구균(葡萄狀球菌)과 고초균(枯草菌) 그리고 그람 음성균(陰性菌)인 대장균(大腸菌)과 녹농균(綠膿菌)을 사용(使用)하였고, 대조물질(對照物質)로는 tetracycline을 사용(使用)하여 상법(常法)에 의(依)해 실험(實驗)하였다. 22개(個)의 처방(處方) 가운데 백두옹탕(白頭翁湯), 황연해독탕(黃連解毒湯), 증황연황연해독탕(增黃連黃連解毒湯), 사심탕(瀉心湯), 용담사간탕(龍膽瀉肝湯), 선방활명음(仙方活命飮) 등(等)의 처방(處方)이 탁월(卓越)한 항균(抗菌) 활성(活性)을 보였다. 이 가운데 본(本) 연구(硏究)에서는 탕제(湯劑)의 구성(構成) 약재(藥材)가 다른 처방(處方)들에 비(比)해 비교적(比較的) 다양(多樣)한 선방활명음(仙方活命飮)에 대(對)해 활성(活性) 성분(成分)의 규명(糾明) 및 구성(構成) 약재간(藥材間)의 상화작용(相互作用)을 밝히고자 하였다. 선방활명음(仙方活命飮) 5 kg을 메탄올 (MeOH)로 추출(抽出)한 뒤 우수(優秀)한 항균(抗菌) 활성(活性)을 보인 에칠아세테이트 (EtOAc) 분획(分劃)에 대(對)하여 silica gel 및 Sephadex LH-20 column chromatography를 반복(反復)하여 stilbene 계열(系列)의 화합물(化合物)인 Rhapontigenin (Compound 1)과 Rhaponticin (Compound 2)을 얻었다. S. aureus SG 511에 대(對)해 Rhapontigenin은 50 mg/ml 이상(以上) 농도(濃度)에서 항균(抗菌) 효과(效果)를 나타내었고, Rhaponticin은 $200\;mg/m{\ell}$ 농도(濃度)에서 미약(微弱)하게 유효(有效)한 항균(抗菌) 효과(效果)를 나타내었으며, B. subtilis ATCC 6633에 대(對)해 Rhapontigenin은 50 mg/ml 이상(以上) 농도(濃度)에서 항균(抗菌) 효과(效果)를 나타내었고, Rhaponticin은 200 mg/ml 농도(濃度)에서 우수(優秀)한 항균(抗菌) 효과(效果)를 나타내었으며, 100 mg/ml 농도(濃度)에서 미약(微弱)하게 유효(有效)한 항균(抗菌) 효과(效果)를 나타내었다. 또한 E. coli 055에 대(對)해서는 Rhapontigenin과 Rhaponticin 모두 200 mg/ml 농도(濃度)에서 미약(微弱)하게 유효(有效)한 항균(抗菌) 효과(效果)를 나타내었다. 이상(以上)의 결과(結果)로 보아 선방활명음(仙方活命飮)의 항균(抗菌) 효능(效能)은 군약(君藥)인 대황(大黃)의 성분(成分) 중(中)의 하나인 stilbene 계열(系列)의 화합물(化合物)인 Rhapontigenin과 Rhaponticin의 작용(作用)에 의(依)한 것이며, 이는 한의학(韓醫學) 방제(方劑) 원리(原理)인 군신좌사(君臣佐使) 이론(理論)에서 군약(君藥)이 주증(主症)에 주(主)로 작용(作用)하는 약물(藥物)이라는 것을 밝혀주는 것이라고 사료(思料)된다.

• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.167-173
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• 1999

Since the resolution of the 2-D hole-to-hole seismic traveltime tomography is affected by the limited ray transmission angle, various methods were used to improve the resolution. Linear traveltime interpolation(LTI) ray tracing method was chosen for forward-modeling method. Inversion results using the LTI method were compared with those using the other ray tracing methods. As an inversion algorithm, SIRT method was used. In the iterative non-linear inversion method, the cost of ray tracing is quite expensive. To reduce the cost, each raypath was stored and the inversion was performed from this information. Using the proposed method, fast convergence was achieved. Inversion results are likely to be affected by the initial velocity guess, especially when the ray transmission angle was limited. To provide a good initial guess for the inversion, generalized regression neural network(GRNN) method was used. When the transmitted raypath angle is not limited or the geological model is very complex, the inversion results are not affected by initial velocity model very much. Since the raypath angles, however, are limited in most geophysical tomographic problems, the enhancement of resolution in tomography can be achieved by providing a proper initial velocity model by another inversion algorithm such as GRNN.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.73-87
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• 1996

The mechanical properties of 2D ceramic composites fabricated bythe newly developed powder infiltration and subsequent multiple impregnation process were characterised by both 3-point flexure and tensile tests. These tests were performed with strain gauge and acoustic emission instrument. The woven fabric composites used for the test have the basic combinations of $Al_{2}$$O_{3}$ fabric/$Al_{2}$$O_{3}$ and SiC fabric (Tyranno)/SiC. Uniaxially aligned SiC fibre(Textron SCS-6)/SiC composites were also tested for comparison, The ultimate flexural strength and first-matrix cracking stress of SiC fabric/SiC composite with 73% of theoretical density were about 300 MPa and 77 MPa respectively. However, the ultimate tensile strengths of composite were generally one third of flexural strengths, and first-matrix cracking stress in a tension test was also much lower than the value obtained from flexure test. The lower mechanical properties measured by tension test were analysed quantitatively bythe differences in stressed volume using Weibull statistics. This showed that the ultimate strength and the firs-tmatrix cracking stress of woven laminate composites were mainly determined bythe gauge length of fibres and the stressed volume of matrix respectively. Incorporation of SiC whiskers into the matrix increased first-matrix cracking stress by increasing the matrix failure strain of composites.

• Tuberculosis and Respiratory Diseases
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• v.40 no.6
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• pp.694-699
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• 1993

Background: After the introduction of more potent antituberculous drugs and the nation-wide tuberculosis management the prevalence rate and mortality rate of pulmonary tuberculosis has been reduced continuously. But we still experienced many patients who succumbed to this disease. So we investigated the causes of treatment failure and death of patients with pulmonary tuberculosis to delineate the problems in the management of these patients. Methods: Retrospective analysis of medical records of 55 patients who died of pulmonary tuberculosis in Kyung-Hee University Hospital during the period of Mar. 1979-Feb. 1990. Results: 1) Average duration of illness was $11.9{\pm}10.1$ years. 2) The mortality rate of in-patients with pulmonary tuberculosis was 2.09%. 3) 47.3% of patients had been treated more than twice and the sputum positive rate was 52.7%. 4) Causes of death were acute respiratory failure(56.4%), asphyxia by hemoptysis(14.6%), cor pulmonale(9.1%), tension pneumothotax(7.3%), vital organ involvement(9.1%) and coexisting diseases(3.5%). Conclusion: Many of these patients had long duration of illness, persistant sputum AFB and high incidence of acute respiratory failure as a fatal complication. It seemed that patient's neglect of their disease and inadequate treatment had caused aggravation of tuberculosis.

• Journal of the Korean Magnetics Society
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• v.9 no.6
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• pp.271-277
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• 1999

Amorphous $Fe_{83}B_9Nb_7Cu_1$ alloy has been studied by M$\"{o}$ssbauer spectroscopy. Revised Vincze method was used and distributions of hyperfine field, isomer shift, and quadrupole line broadening of the sample at various temperatures have been evaluated and Curie temperature and $H_{hf}\;(0)$ were calculated to be 393 K and 231 kOe, respectively. Temperature variation of reduced average hyperfine field shows a flattered curvein comparison with the Brillouin curve for S=1. This behavior can be explained on the basis of Handrich molecular field model, in which the parameter Δ, which is a measure of fluctuation in exchange interactions, is assumed to have the temperature dependence ${Delta}=0.75-0.64{\tau}+0.47{\tau}^2$ where $\tau$ is $T/T_C$. At low temperature, the average hyperfine field can be fitted to $H_{hf}\;(T)=H_{hf}\;(0)\;[1-0.44\;(T/T_C)^{3/2}-0.28(T/T_C)^{5/2}-… ]$, which indicates the presence long wave length spin wave excitations. At temperature near TC, reduced average hyperfine field varies as $1.00\;[1-T/T_C]^{0.39}$. It is also found that half-width of the hyperfine field distribution was 102 kOe (3.29 mm/s) at 13 K and decreased monotonically as temperature increased. Above the Curie temperature, an average quadrupole splitting value of 0.43 mm/s was found. Average line broadening due to quadrupole splitting distribution was 0.31 mm/s at 13 K and decreases monotonically to 0.23 mm/s at 320 K, whereas that due to the isomer shift distribution is 0.1 mm/s at 13 K and 0.072 mm/s at 320 K, which is much smaller than that of both hyperfine field and quadrupole splitting. The temperature dependence of the isomer shift can be fitted within the harmonic approximation to a Deybe model with a Debye temperature ${Theta}_D=424{\pm}5K$.TEX>.

• Journal of Korea Water Resources Association
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• v.45 no.1
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• pp.39-52
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• 2012

Surface-subsurface interactions are an intrinsic component of the hydrologic response within a watershed. In general, these interactions are considered to be one of the most difficult areas of the discipline, particularly for the modeler who intends simulate the dynamic relations between these two major domains of the hydrological cycle. In essence, one major complexity is the spatial and temporal variations in the dynamically interacting system behavior. The proper simulation of these variations requires the need for providing an appropriate coupling mechanism between the surface and subsurface components of the system. In this study, an approach for modelling surface-subsurface flow and transport in a fully intergrated way is presented. The model uses the 2-dimensional diffusion wave equation for sheet surface water flow, and the Boussinesq equation with the Darcy's law and Dupuit-Forchheimer's assumption for variably saturated subsurface water flow. The coupled system of equations governing surface and subsurface flows is discretized using the finite volume method with central differencing in space and the Crank-Nicolson method in time. The interactions between surface and subsurface flows are considered mass balance based on the continuity conditions of pressure head and exchange flux. The major module consists of four sub-module (SUBFA, SFA, IA and NS module) is developed.