• 산업기술연구
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• 제21권B호
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• pp.325-330
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• 2001

In this research, the early-age movements of joint at JPCP(Jointed Plain Concrete Pavement) were measured by field tests. The field tests were carried out for 5 days just after concrete placement, for 1 day after 52 and 72 days on Chung-Ang Expressway construction site in Dan-yang on the 28th and 29th of May 2001. The joint movements were measured by demec gauge and clip gauge. The results of regression analysis for the data measured during early 5 days showed that the joints of No.4, No.5, No.6, No.10, No.13, and No.15 could be considered as a moving joint. From data analysis on july 20, the joints of No.2, No.9, and No.10 showed the significant correlations from the minus value of coefficient of regression. As a result of regression data on August 8, joint movements occurred at all joints. Joint freezing and closure could be judged from the regression analysis using joint opening and total temperature measured at field tests.

• 물과 미래
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• 제29권2호
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• pp.199-207
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• 1996

온배수의 거동해석에 $\kappa-\imath$ 난류모델의 사용성 평가를 위해 수심적분 2차원 수치모형을 개발하였다. 개발된 모형은 간단한 단면을 갖는 개수로 정상류의 경우에 적용하였으며, 기존의 실험결과와 비교적 잘 일치하였다. 온수의 재순환, 재부착 및 초과온도 상승분포의 적절한 모의해석은 $\kappa-\imath$ 난류모델에 의한 적절한 난류 점성 및 확산계수의 산정때문이라 생각된다. 예측의 정확성을 위하여 부력생성항의 도입, Source/Sink 항의 수정 및 그에 따른 적절한 난류 상수의 규명이 필요하다.

• 한국안전학회지
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• 제16권1호
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• pp.18-24
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• 2001

The fatigue crack growth behavior of the SA516/70 steel which is used for pressure vessels was examined experimentally at room temperature, $-60^{\circ}C$,$-80^{\circ}C$ and $-100^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. Fatigue crack propagation rate da/dN related with stress intensity factor range ${\Delta}K$ was influenced by stress ratio in stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to the extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the plasticity induced and roughness induced.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.80-87
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• 2001

The fatigue crack growth behavior of the SA516/60 steel which is used for pressure vessels was examined experimentally at room temperature $25^{\circ}C, -30^{\circ}C, -60^{\circ}C, -80^{\circ}C, -100^{\circ}C$ and -l2$0^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. Fatigue crack propagation rate da/dN related with stress intensity factor range ΔK was influenced by stress ratio in stable of fatigue crack growth (Region II) with an increase in ΔK. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to the extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the plasticity induced and roughness induced.

• 한국학교보건학회지
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• 제28권3호
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• pp.188-199
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• 2015

Purpose: This study aims to understand schools' response to infectious disease, perceived problems and suggestions, with regard to the 2015 MERS outbreak in South Korea, in order to improve the infectious disease response system. Methods: Data were collected by focus group interviews with three groups composed of school health teachers, other teachers, and parents in Seoul-located schools. Results: The major theme was "Schools' Discretionary Response in the Absence of the Control Tower." Four major categories and 11 sub-categories were drawn from the findings. Four major categories were as follows: (a) Temperature monitoring caused lots of complaints, (b) Closure decisions were left at the discretion of schools, (c) Precautions are now being more emphasized, and (d) The support system were malfunctioning. Conclusion: The main areas to be improved are as follows: (1) School district offices should have an expanded role in infectious disease response and build cooperative partnerships with health authorities. (2) Preparedness for infectious disease should be strengthened. (3) Temperature monitoring systems should be improved, (4) Closure decisions should be made at a local community level. These are expected to help schools establish advanced infectious disease response systems.

• 동력기계공학회지
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• 제3권2호
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• pp.51-56
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• 1999

Fatigue crack propagation rates and characteristics of the SA516-70 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $10^{\circ}C$ and low temperature ranges of $-10^{\circ}C,\;-30^{\circ}C,\;-50^{\circ}C,\;and\;-70^{\circ}C$ with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN > $8{\times}10^3$ mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of low crack propagation rate. 2) The lower limit stress intensity factor of SA516-70 ${\Delta}K_{th}\;was\;23MPa\sqrt{m}$ and in the case of low temperature $-50^{\circ}C\;and\;-70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the ${\Delta}K_{th}$. As the results, the crack propagation rates of $-50^{\circ}C\;and\;-70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the ${\Delta}K_{th}$. 3) On the relationship between the stress intensity factor ${\Delta}K$ and the track propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but ${\Delta}K$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.240-245
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• 2000

Fatigue crack propagation rates and characteristics of the SA516-60 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $25^{\circ}C$ and low temperature ranges of $10^{\circ}C,\; -10^{\circ}C,\; -30^{\circ}C,\; -50^{\circ}C, \;and\; -70^{\circ}C4 with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN 〉$8\times10^{-3}$/mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of crack propagation rate. 2) The lower limit stress intensity factor of SA516-60 $\DeltaK_{th}$ was 15.8MPa and in the case of low temperature $-50^{\circ}C\; and\; -70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the $\DeltaK_{th}$/. As the results, the crack propagation rates of $-50^{\circ}C\; and\; -70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the $\DeltaK_{th}$/. 3) On the relationship between the stress intensity factor $\DeltaK$ and the crack propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but $\DeltaK$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.473-478
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• 2004

This work presents the Thermal Hydraulic analysis has been performed for a 19-pin wire-spacer fuel assembly using three-dimensional Reynolds-averaged Navier-Stokes equations. SST model is used as a turbulence closure. The whole fuel assembly has been analyzed for one period of the wire-spacer using periodic boundary condition at inlet and outlet of the calculation domain. The overall results far a preliminary calculation show a good agreement with the experimental observations. It has been found that the major unidirectional flows are the axial velocity in sub-channels and the peripheral sweeping flows and the velocities are found to be following a cyclic path of period equal to the wire-wrap pitch. The temperature is found to be maximum in the central region and also, there exist a radial temperature gradient between the fuel rods. The major advantage of performing this kind of analysis is the prediction of thermal-hydraulic behavior of a fuel assembly with much ease.

• 플랜트 저널
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• 제14권1호
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• pp.42-46
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• 2018

The flow and heat transfer characteristics inside a solar chimney power plant system are analyzed in this article. 3-D model with the $k-{\varepsilon}$ turbulence closure was developed. In this model, to solve the radiative transfer equation the discrete ordinates radiation model was implemented, using a two-band radiation model. To simulate radiation effects from the sun's rays, the solar ray tracing algorithm was coupled to the calculation via a source term in the energy equation. Simulations were carried out for a system with the geometry parameters of the Manzanares power plant. Based on the numerical results, the velocity and temperature distributions were illustrated and the results were validated by comparing with experimental data of the Manzanares prototype power plant. Moreover, temperature profile of the ground surface of the system was illustrated.

• Bulletin of the Korean Chemical Society
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• 제20권12호
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• pp.1464-1468
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• 1999

Non-activated indolinobenzospiropyrans, 6-(p-substituted phenylazo)-1',3',3'-trimethylspiroindolinobenzopyrans(1-4) have been synthesized by the reaction of commercially available Fischer's base with 2-hydroxy-5-arylazobenzaldehyde (S1-S4). The arylazosalicylaldehydes were obtained from the diazocoupling reaction of substituted anilines with salicylaldehyde. The rate of spiro-ring formation from the open form of these nonactivated spiropyran derivatives at room temperature has been investigated utilizing the stopped-flow method de-veloped earlier. Half life times $(t_{1/2})$ of the ring-closure reaction in ethanol are about 0.3-14 seconds for the nonactivated spiropyrans examined. UV-Visible absorption spectral data of the open merocyanine form of nonactivated spiropyrans, which showed no chromotropism at room temperature, have also been obtained.