• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.205-210
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• 1998

The strength and dimension of recent constructed subway box structures are increased considerably. These increases are resulting in much initial cracks by hydration heat and thermal stress. According to previous studies, decrease of cement amount by using superplasticizer and L/H value is the best way to eliminate hydration heat and stress. The analyses using finite element model were performed. By the result of analysis, the use of superplasticizer and the decrease of the change of longitudinal placing length are proved to be more effective for elimination thermal cracks. By ACI Code, for longitudinal placing length 25 m, the amount of wall temperature reinforcement is always lack despite of concrete mix proportion. With analytical result and the inducing crack joint, the in-site test were performed and the analytical results proved to be effective. However, the inducing crack joint is not effective if it is a small size.

• Journal of Korean Neurosurgical Society
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• 제54권2호
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• pp.145-147
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• 2013

We present a case of acute hydrocephalus secondary to cervical spinal cord injury in a patient with diffuse ossification of the posterior longitudinal ligament (OPLL). A 75-year-old male patient visited the emergency department with tetraparesis and spinal shock. Imaging studies showed cervical spinal cord injury with hemorrhage and diffuse OPLL from C1 to C4. We performed decompressive laminectomy and occipitocervical fusion. Two days after surgery, his mental status had deteriorated to drowsiness with dilatation of the right pupil. Findings on brain computed tomography revealed acute hydrocephalus and subarachnoid hemorrhage in the cerebellomedullary cistern, therefore, extraventricular drainage was performed immediately. Acute hydrocephalus as a complication of cervical spine trauma is rare, however, it should be considered if the patient shows deterioration of neurologic symptoms.

• Journal of the Korean Statistical Society
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• 제29권2호
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• pp.201-217
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• 2000

The method of generalized estimating equations (GEE) has become very popular for the analysis of longitudinal data. We extend this work to the use of M-estimators; the resultant regression estimates are robust to heavy tailed errors and to outliers. The proposed method does not require correct specification of the dependence structure between observation, and allows for heterogeneity of the error. However, an estimate of the dependence structure may be incorporated, and if it is correct this guarantees a higher efficiency for the regression estimators. A goodness-of-fit test for checking the adequacy of the assumed M-estimation regression model is also provided. Simulation studies are conducted to show the finite-sample performance of the new methods. The proposed methods are applied to a real-life data set.

• 한국수소및신에너지학회논문집
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• 제12권1호
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• pp.51-63
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• 2001

In this paper molecular dynamics simulations were employed to investigate the structural and dynamic properties of hydrogen ions impacted on the Ni (100) surface with the $45^{\circ}$ incident angle. The initial kinetic energies of the hydrogen ion range from 100 to 1,600 eV. Together with the trajectory visualization of hydrogen ions, we computed scattering and penetration yields, mean energies and angles, and probability and energy distributions as a function of longitudinal and azimuthal directions. In the case of lower energy scattering ions, the multiple collision effects were found to be important to the third layers or lower. For higher energy penetrating ions, compared with the normal incident angle, it was significant the effective channeling effects through the Ni layers and the angle dependencies were indicated both in the longitudinal and the azimuthal angle directions.

• Journal of the Optical Society of Korea
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• 제13권4호
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• pp.484-488
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• 2009

We investigate the characteristics of the surface mode formed at the single interface between dual singly negative medium layers. It is shown that the interface can support a mode which has polarization degeneracy and a vanishing propagation constant. That is, this surface mode is a polarization-independent one that does not propagate at all through the interface. The corresponding electric and magnetic field distributions become static along the longitudinal (guiding) direction (but not along the transverse direction) resulting in the formation of transverse-electric/longitudinalmagnetic or transverse-magnetic/longitudinal-electric modes.

• 한국기계연구소 소보
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• 통권19호
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• pp.5-14
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• 1989

Analytical and experimental studies are performed to identify the longitudinal vibration characteristics of elevator system such as the natural frequencies, and the magnification factor at resonance. In the analytical study, a computer program is developed to analyze the vibration characteristics of elevator with varing rope length of elevtor, stiffenss of thimble rod spring, and excitation frequency. The shorter rope length and the stiffer thimble rod spring make the natural frequencies of elevator higer. The resonance at the first natural frequency spreads over the entire travelling range, whereas, that at the second one ranges relatively short, region. The first natural frequencies of the Gald-Star Twin Building and the Korea Trading Center Building obtained by the experiment are overall in good agreement with the analysis result..

• 한국경영과학회지
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• 제28권2호
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• pp.35-59
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• 2003

Generally high-tech ventures have few resources with which to withstand unpredictable environmental jolts. Therefore environmental changes may have severe effects on the performance of high-tech ventures. Unfortunately previous empirical studies for predicting the performance of ventures hardly deal with such dynamic changes of performance. We try to examine the performance changes of ventures through a longitudinal study before and after severe environmental changes, namely IMF Bailout Memorandum. For the empirical study, we classified venture firms into four types based on entrepreneur's assessment of their performance changes and investigated how these four types differ in characteristics of entrepreneurs, environment, strategy, and organizational features. We found that differentiation strategies, fit between strategy and environmental changes, entrepreneur's trust and activities such as networking and knowledge accumulation about customers, and decentralized organizational structure were important to the performance changes of high-tech ventures.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.781-787
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• 2004

Where the track is continuously welded over a bridge, the longitudinal force is interacted between the track and the sub-structure. Due to this respect, the expansion joint is used to decrease this force. But the expansion joint has several problems related to passenger comfort and maintenance etc. In this study, it is analysed about how the stability of the track is affected as the span length becomes longer in case of 2-span continuos bridge. It is found that there is no problem of an stability unless the span length is longer than 90m when the elastic shoe is used. And several parametric studies were also implemented.

• 대한치과의사협회지
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• 제13권10호
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• pp.947-950
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• 1975

For biometric study on the width of mouth in the vietnamese, the author measured the transversal width of mouth and longitudinal width of mouth in 1021 healthy cases. of the total cases, 506 were male and 506 female and ages ranged from 1 to 30 over years old. The following result was obtained: 1) In adult, transverasal width of mouth was 49.23±0.24 in male, 49.67±0.31 in female and 39.14±0.22 in male, 41.01±0.23 in female of children. 2) In adult, longitudinal width of mouth was 52.82±0.24 in male, 51.89±0.28 in female and 40.92±0.37 in male, 42.97±0.29 in female of children.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.109-118
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• 1999

Lifeline system such as oil or gas pipelines and water supply facilities are vulneratble to seismic damages because they are widely exposed to ground failures. Most seismic design criteria of buried pipelines are based on the notion that the longitudinal compressive strain and therefore buckling controls the design. Buckling analysis of buried pipelines subjected to seismic loading is performed by considering the seismic load as the sinusoidally distributed compressive load on the beam on elastic foundation in contrast to existing studies where the buckling load is treated as an end load on the beam column, An approximated analytical solution is obtained by the energy method and its validity is confirmed by the linearized finite element buckling analysis. The results show the beam mode buckling because longitudinal strains at the buckling loads are substantially lower than the strain at the onset of local buckling.