• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6C
• /
• pp.359-366
• /
• 2008

The load distribution and deformation of pile subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance that is closely related to the ratio of pile diameter to soil modulus $(D/E_s)$ and the ratio of total shaft resistance against total applied load $(R_s/Q)$, in rock-socketed drilled shafts using the coupled load-transfer method. The proposed analytical method that takes into account the soil coupling effect was developed using a modified Mindlin's point load solution. Through comparisons with field case studies, it was found that the proposed method in the present study estimated reasonable load transfer behavior of pile and coupling effects due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.12C
• /
• pp.1020-1028
• /
• 2010

Relay has attracted great attention due to its inherent capability to extend the service coverage and combat shadowing in next generation mobile communication systems. So far, most relay technologies have been developed under the half-duplex (HD) constraint that prevents relays from transmitting and receiving at the same time. Although half-duplex relay (HDR) is easy to implement, it requires partitioning of resource for transmission and reception, reducing the whole system capacity. In this paper, we propose a multinser precoding and power control scheme with sum rate matching for a full-duplex (FD) multiple-input multiple-output (MIMO) relay. Full-duplex relay (FDR) can overcome the drawback of HDR by transmitting and receiving on the same frequency at the same time, while it is crucial to reduce the effect of self-interference that is caused by its own transmitter to its own receiver. The proposed precoding scheme cancels the self-interference of the FDR as well as to support multiuser MIMO. Moreover, we suggest a power allocation scheme for FD MIMO relay with the constraint that the sum rate of the relay's received data streams is equal to that of the relay's transmit data streams.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.77-81
• /
• 2019

식생전이에 따른 기간분리는 해외 및 국내 논문에서 식생영향을 받지 않는 곡선식과의 차이를 검토하고, 측정성과별 분류를 통해 곡선식을 개발하는 방법이 제시하고 있으나 적용기간 설정에 대한 구체적인 방법이 없다. 또한 상하류 비교를 통해 기간분리의 적정성을 검토할 수 있다고 명시되어 있으나 비교 관측소가 없는 경우 검토에 어려움이 있다. 본 연구는 2017년 수위-유량관계곡선식의 적용시간 결정에서 현장 식생모니터링 자료와 함께 연간 수온변화를 참고 자료로 활용하였다. 연간 수온자료를 산정하기 위해 측정된 수온과 해당 기온에 대한 상관관계식을 개발하였다. 또한 산포가 발생하는 측정성과는 생성된 연간 수온자료를 참고하여 전이여부를 판단하였다. 2018년은 2017년의 계절별 수온변화 자료 및 수집된 주요 수중식생의 생활사를 참고하여 연간 측정계획에 활용하였으며, 수위-유량관계곡선식 개발 시 동일한 방법을 사용하였다. 2017년은 가뭄으로 인해 수중식생에 의한 전이가 활발했던 기간으로 측정성과에 대해 식생영향 최고 기간과 최대 기간의 동일수위에 대해서 유량을 비교한 결과 $0.003m^3/s{\sim}1.099m^3/s$의 범위를 보였다. 유출량 비교의 경우 기간분리를 적용하지 않았을 경우 약 40.1% 과대 산정되었다. 2018년은 잦은 강우로 인해 수중식생의 이탈 및 전이 영향수위의 발생빈도가 비교적 적어 동 수위 유량을 비교한 결과 $0.19m^3/s{\sim}0.49m^3/s$의 범위를 보였다. 연 유출량을 비교한 결과, 기간분리를 고려하지 않은 경우가 약 39.6%로 과소 산정되었다. 따라서 본 연구사례를 통해 식생에 의한 기간분리가 발생하는 지점에 대해서 비교적 합리적인 측정주기 계획을 위한 확립 근거와 기간분리 적용기간에 대한 합리적인 자료로 활용 될 수 있을 것이다.

• Journal of the Korean Magnetics Society
• /
• v.9 no.3
• /
• pp.143-148
• /
• 1999

Magnetic properties and crystallographic properties of $Cu_{1-x}Ge_{1-y}Fe_{x+y}O_3$ system were studied by using x-ray diffraction, superconducting quantum interference device (SQUID) and Mossbauer spectroscopy. All the samples have orthorhombic structure and the lattice constants some decreased as the substituted iron contents increasing. The spin-Peierls (SP) transition temperature of our samples are about 12.5 K and these temperatures lowered as increasing substituted iron contents. The Mossbauer spectra consisted with two Zeeman sextets and one doublet due to $Fe^{3+}$ ions. The jump up of magnetic hyperfine field of 2nd Zeeman sextet and the increasing of the values of quadrapole splitting and isomer shift of doublet below SP transition temperature could be interpreted with the variation of the superexchange interaction, the symmetry of lattice sites and the covalency of bonds due to the atomic displacements.

• Applied Chemistry for Engineering
• /
• v.22 no.2
• /
• pp.155-160
• /
• 2011

An animal fat is an attractive biodiesel energy source for its high stability against oxidation and low incomplete combustion ratio due to the high heating value and cetane value. However, it requires a refinery process because of the high content of saturated acid and impurity which increas the boiling point. In this study, the optimum biodiesel synthetic process of lard is suggested. Indeed, we demonstrate new biodiesel production processes to alter conventional process of heating and mixing by applying ultrasonic energy. While the optimum reaction temperature and mole ratio of methanol and lard, when using conventional mixing and heating process, were $55^{\circ}C$ and 12, respectively, the reaction time were reduced to 30 minutes by applying ultrasonic irradiation power of 500 W. The new process applying ultrasonic irradiation yielded synthetic biodiesel properties as followings: 3.34 cP of the viscosity, 37.0 MJ/kg of the caloric value and below 0.25 mgKOH/g of the acidic value, which satisfy biodiesel quality criteria.

• Journal of Biomedical Engineering Research
• /
• v.25 no.4
• /
• pp.243-251
• /
• 2004

This study was to quantitative analysis compare to dynamic characteristic change of the regional cerebral blood volume (rCBV) after development of cerebral fat embolism in cats using perfusion MR Imaging. Forty-four adult rats were used. Triolein (n = 15), oleic acid (n = 9) and linoleic acid (n = 11) were injected into the internal carotid artery using microcatheter through the transfemoral approach. Polyvinyl alcohol (Ivalon) (n = 9) was injected as a control group. Perfusion MR images were obtained at 30 minutes and 2 hours after embolization, based on T2 and diffusion-weighted images. The data was time-to-signal intensity curve and ΔR$_2$＊ curve were obtained continuously with the aid of home-maid image proc in.leased significantly at 2 hours compared with those of 30 minutes (P＜0.005). In conclusion, cerebral blood flow decreased in cerebral fat embolism immediately after embolization and recovered remarkably in time course. It is thought that clinically informations to dynamic characteristic change of the cerebral hemodynamics to the early finding in cerebral infarction by DWI and PWI

• Communications for Statistical Applications and Methods
• /
• v.16 no.2
• /
• pp.217-228
• /
• 2009

In this paper, we consider a multi-class queueing system in which different classes of customers have different arrival rates, service rates and class-transition probabilities. We use the fast simulation method to estimate the overflow probability and the expected number of customers of each class at the first time the total number of customers hits a high level. We also discuss the overflow probabilities and the expected number of customers at different loads, respectively.

• Journal of Oral Medicine and Pain
• /
• v.31 no.1
• /
• pp.47-57
• /
• 2006

The purpose of this study was to assess the effects of the superficial heat therapy on the cutaneous blood flow and the skin temperature at pre-auricular region. Two types of the superficial heat therapy-moist hot pack & infrared lamp- were applied to 20 healthy subjects(male: 10, female: 10). For each subject, the two parameters of cutaneous blood flow and skin temperature were measured before and after heat therapy, using laser doppler flowmetry(LDF). The author analyzed the differences of the effects between the two therapies and also characteristics of responsiveness between the two parameters. The results were as follows : 1. The two parameters were significantly increased after both superficial heat therapies. 2. Skin temperature showed a maximum peak immediately after both superficial heat therapies, but cutaneous blood flow showed a maximum peak 4 minutes after both superficial heat therapies. 3. Increased cutaneous blood flow after application of moist hot pack lasted longer than infrared lamp. 4. Increased skin temperature after both superficial heat therapies lasted for 60 minutes, but increased skin temperature after infrared lamp decreased more rapidly than moist hot pack. 5. Amount of changes in cutaneous blood flow after infrared lamp was larger in female than in male, but no significant gender difference was found since 20 minutes after infrared lamp. Both moist hot pack and infrared lamp showed favorable effectiveness in raising cutaneous blood flow and skin temperature. Moist hot pack was slightly superior in maintaining this effect.

• 한국전자현미경학회:학술대회논문집
• /
• 1999.11a
• /
• pp.54-58
• /
• 1999

GaAs 위에 증착된 ZnTe 박막의 계면 구조를 투과 전자 현미경을 이용하여 관찰하였다. 2-빔 조건을 사용하여 관찰된 계면에서 모아레 즐무늬가 관찰되었으며, 이러한 모아레 줄무늬의 생성원리를 규명하였다. 또한 고분해능 투과 전자현미경상으로부터 얻어진 결과와 비교하여 ZnTe의 성장방식 전이 및 섬 구조를 가지는 ZnTe 박막의 여러 가지 구조적 성질들 - 섬의 크기, 변형량, $60^{\circ}$ 전위의 분포 등 - 에 대해 밝혔다. 이러한 결과들은 큰 변형량이 걸린 반도체 이종 접합 구조의 해석에 일반적으로 적용될 수 있다.

• Journal of the Korean Geotechnical Society
• /
• v.31 no.10
• /
• pp.49-60
• /
• 2015

Since previous studies on the 3-dimensional earth pressure have been conducted focusing on the stability of wall, it is very difficult to find a study on the load transfer to the adjacent ground induced by the 3-dimensional active displacement. Therefore, in this study, we tried to find out the load transfer to the adjacent ground induced by the 3-dimensional active displacement depending on the size of rectangular wall which was defined by the aspect ratio, that is, the ratio of the height to the width of the wall. 3-dimensional model tests were performed in order to measure the distribution and the magnitude of load transfer to surrounding grounds. The transferred load was 17.9~30.6% less than the difference between the 3-dimensional active earth pressure and earth pressure at rest. The transferred load of both vertical and horizontal was maximum at the boundary of the active wall. The load transfer range depended on the normalized height of the active wall, and it was 0.67~1.29w in horizontal direction and 1.0~3.0h in vertical direction. The transferred load in horizontal was maximum at the height of the wall. As the aspect ratio increases the location of the maximum transferred load points becomes higher. The ratio of the transferred load area of 56~79% at 0.25w in horizontal direction and 50~58% at 1.0~1.5 in vertical direction. Diagrams showing the distribution and the magnitude of the transferred load depending on the aspect ratio were suggested.