• Annals of Clinical Neurophysiology
• /
• 제1권1호
• /
• pp.1-9
• /
• 1999

Since Hans Berger reported the first paper on the human electroencephalogram in 1920s, huge technological advance have made it possible to use a number of electrophysiological approaches to neurological diagnosis in clinical neurology. In majority of the neurology training hospitals they have facilities of electroencephalography(EEG), electromyography(EMG), evoked potentials(EP), polysomnography(PSG), electronystagmography(ENG) and, transcranial doppler(TCD) ete. Clinicials and electrophysiologists should understand the technologic characteristics and general applications of each electrophysiological studies to get useful informations with using them in clinics. It is generally agreed that items of these tests are selected under the clinical examination, the tests are performed by the experts, and the test results are interpretated under the clinical background. Otherwise these tests are sometimes useless and lead clinicians to misunderstand the lesion site, the nature of disease, or the disease course. In this sense the clinical utility of neurophysiological tests could be summerized in the followings. First, the abnormal functioning of the nervous system and its environments can be demonstrated when the history and neurological examinations are equivocal. Second, the presence of clinically unsuspected malfunction in the nervous system can be revealed by those tests. Finally the objective changes can be monitored over time in the patient's status. Also intraoperative monitoring technique becomes one of the important procedures when the major operations in the posterior fossa or in the spinal cord are performed. In 1996, the Korean Society for Clinical Neurophysiology(KSCN) was founded with the hope that it will provide the members with the comfortable place for discussing their clinical and academic experience, exchanging new informations, and learning new techniques of the neurophysiological tests. The KSCN could collaborate with the International Federation of Clinical Neurophysiology(IFCN) to improve the level of the clinical neurophysiologic field in Korea as will as in Asian region.1 In this paper the clinical neurophysiological tests which are commonly used in clinical neurology and which will be delt with and educated by the KSCN in the future will be discussed briefly in order of EEG, EMG, EP, PSG, TCD, ENG, and Intraoperative monitoring.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
• /
• pp.491-496
• /
• 2000

This paper presents the evaluation of behavior and the prediction of tensile capacity of anchors that fail concrete, as the design basis for anchorage. Tests of cast-in-place headed anchors, domestically manufactured and installed in uncracked, unreinforced concrete are performed to investigate the behavior of single anchors and multiple anchors with the consideration of various embedment lengths and edge distances. The failure mode and the load-deformation response of these anchors are discussed and the concrete failure dta are then compared with capacity predictions by the two existing methods : the 45 degree cone method of ACI 349, 318 and the concrete capacity design (CCD) method. Discrepancies between the test results and these two prediction methods, FEM analysis are assessed.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
• /
• pp.247-250
• /
• 2005

The aim of Cast-In-Place(CIP) method is to upgrade the strength, ductility and stiffness of the structure to the required level. The main objective of this research is to investigate the shear and the flexural strength of reinforced concrete frames infilled with CIP reinforced concrete wall. For this three 1/3 scale, one-bay, one story reinforced concrete infill wall were tested under reversed cyclic loading simulating the seismic effect. Results of tests of CIP shear wall were reviewed to evaluate the current design provisions and to establish the feasible retrofitting method.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 가을 학술발표회 논문집
• /
• pp.553-560
• /
• 2002

The improvement effect of soft ground is estimated by unconfined strength mainly. The unconfined strength of solidification agent treated soil is likely to vary with ununiformed mixing ratio and water content change of in-situ ground place by place. So, it is unreasonable to apply a solidification agent mixing ratio obtained from laboratory test results on all over the soft ground. In this study, it was analysed how the unconfined strength would be effected by the water content of soft ground. For this study, a series of unconfined compressive tests are peformed on various water content soil samples. The test results showed that the strength was fallen to 30∼80% by two times increase of water content approximately, This means that strength of solidification agent treated soil is influenced greatly by water content of raw soft ground and mixing ratio of solidification agent. It was suggested that the method how to decide the mixing ratio with soft ground water content.

• 한국강구조학회 논문집
• /
• 제27권3호
• /
• pp.347-357
• /
• 2015

본 연구에서는 지진모의실험으로 비보강 선설치앵커의 전단에 대한 콘크리트 파열파괴강도를 평가하기 위한 실험 연구를 수행하였다. 이를 위해 앵커 직경 30mm, 연단거리 150mm, 매입깊이 240mm인 비균열 시험체와 전단하중에 수직 및 수평 방향 균열콘크리트 시험체들에 대해 각각 실험을 수행하였다. 지진모의실험 시 동적 가력은 CSA N287.2, ACI 355.2와 ETAG 001 기준을 참조하여 결정하였으며 이후 파괴 시까지 정적 재하를 실시하였다. 비균열 및 균열콘크리트 모두 지진모의실험에 의한 저항강도는 각각 정적 강도와 거의 동등한 수준이었다. 한편, 콘크리트 파괴단면의 깊이는 $8d_0$에 모두 미치지 못하였으며 이로부터 기존 강도식에 비해 유효지압길이를 고려하지 않는 ACI 318-11의 수정강도식이 콘크리트 파열파괴강도를 적절하게 평가하는 것으로 분석되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 봄 학술발표회 논문집
• /
• pp.279-286
• /
• 2002

Recently, there are many attempts to expand a temporary soil nailing system into a permanent wall due to the advantage of soil nailing system, that is efficient and economic use of underground space and decreasing the total construction cost. However, the proper design approach of a permanent soil nailing system has not been proposed by now in Korea. Permanent soil nailing system which utilizes precast concrete walls for the facing of soil nailing system Is already used in many countries. In general, the cast-in-place concrete facings or rigid walls were constructed in bottom-up way after construction of soil nailing walls finished preliminarily In this paper, various laboratory model tests have been carried out to investigate the failure mode, behavior characteristics, and tensile force at nail head in each load level in respects of the variation of stiffness of the facing.

• Geomechanics and Engineering
• /
• 제36권2호
• /
• pp.145-156
• /
• 2024

The mechanical properties of the concrete-frozen soil interface play a significant role in the stability and service performance of construction projects in cold regions. Current research mainly focuses on the precast concrete-frozen soil interface, with limited consideration for the more realistic cast-in-place concrete-frozen soil interface. The two construction methods result in completely different contact surface morphologies and exhibit significant differences in mechanical properties. Therefore, this study selects silty clay as the research object and conducts direct shear tests on the concrete-frozen soil interface under conditions of initial water content ranging from 12% to 24%, normal stress from 50 kPa to 300 kPa, and freezing temperature of -3℃. The results indicate that (1) both interface shear stress-displacement curves can be divided into three stages: rapid growth of shear stress, softening of shear stress after peak, and residual stability; (2) the peak strength of both interfaces increases initially and then decreases with an increase in water content, while residual strength is relatively less affected by water content; (3) peak strength and residual strength are linearly positively correlated with normal stress, and the strength of ice bonding is less affected by normal stress; (4) the mechanical properties of the cast-in-place concrete-frozen soil interface are significantly better than those of the precast concrete-frozen soil interface. However, when the water content is high, the former's mechanical performance deteriorates much more than the latter, leading to severe strength loss. Therefore, in practical engineering, cast-in-place concrete construction is preferred in cases of higher negative temperatures and lower water content, while precast concrete construction is considered in cases of lower negative temperatures and higher water content. This study provides reference for the construction of frozen soil-structure interface in cold regions and basic data support for improving the stability and service performance of cold region engineering.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.179-182
• /
• 2007

The compressive fatigue tests on the closed cell Al-Si-Ca alloy foams with two different thicknesses were performed using a load ratio of 0.1. The quasi-static and cyclic compressive behaviors were obtained respectively. The fatigue stress-life (S-N) curves were evaluated from the obtained cyclic compressive behaviors. S-N curves were presented for the onset of progressive shortening. It turned out that the fatigue strength showed higher value for the thicker foam and the onset of shortening of thinner foam took place earlier. The crushing was found to initiate in a single band which broadens gradually with additional fatigue cycles. Progressive shortening of the specimen took place due to a combination of low cycle fatigue failure and cyclic ratcheting.

• Computers and Concrete
• /
• 제3권2_3호
• /
• pp.91-102
• /
• 2006

To place concrete overlays has become a standard application in the strengthening and rehabilitation of concrete structures such as bridges, tunnels, parking decks and industrial buildings. In general, connectors are used to ensure a monolithic behavior of the two concrete layers. Within the framework of the development of a new connector wedge splitting tests and shear tests were performed, in addition nonlinear finite element analyses were applied to investigate the load transfer behavior of the connectors for different prototypes. The numerical simulation results were compared to experimental data. The computed load-displacement curve demonstrates good correspondence with the curves obtained in the experiments, and the experimental crack patterns are reasonably simulated by the computed crack propagation. Both numerical and experimental investigations on the wedge splitting test and on the shear test served as basis for the development of new type of connectors.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 1998년도 공동 심포지엄 및 추계학술발표회
• /
• pp.81-85
• /
• 1998

In the present study, the design method of containment walls is proposed by utilizing an existing site. The selected remedy for the Source Area of Operable Unit 2 at Hill Air Force Base stipulated containment of the pure-phase trichloroethylene contamination. The in-place-mixed wall construction was selected because of the irregular topography, small area of the site, and the requirement to reach depths of greater than 90 feet below ground surface. Bench-scale compatibility studies were performed for the containment wall mix design on three commercial bentonite clays. The samples were subject to screening tests and long-term tests for evaluation of changed soil properties when exposed to the contaminated groundwater.