• The Journal of the Korean dental association
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• v.26 no.10 s.233
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• pp.945-948
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• 1988

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.93-100
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• 2021

The purpose of this study is to find out the factors that affect the patient's exposure dose during the abdominal CT scan using the bolus tracking technique, and reducing the radiation exposure to the patient during the abdominal CT scan using the bolus tracking technique by adjusting the delay time according to the corresponding factor. The experiment was divided into two parts, and the first experiment was conducted with 300 patients There were 188 males and 112 females, and their average age was 58±12.18(19~85). In the second experiment, 150 subjects (100 males and 50 females) who were undergoing their follow-up examination among the first experiment subjects, and the difference in dose before and after was compared by applying the delay time according to the influencing factor. As a result of the first experiment, there was a relationship between the arrival time of the contrast media and the heart rate, and it was found that the arrival time decreased as the heart rate increased for both men and women. As a result of the second experiment, the average dose of CTDIvol and DLP before/after applying the delay time according to the heart rate decreased 4.98 mGy and 5.33 mGy·cm in the male group, and 3.54 mGy and 3.88 mGy·cm in the female group. By applying proper delay time according to the patient's heart rate during abdominal CT scan with the bolus tracking technique, the radiation exposure dose of the patient can be reduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.239-245
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• 2009

Levees, the hydro-engineering structure, are similar to earth dams in aspects of shape and structure. However, they are different from earth dams in the external force conditions. As a levee is the structure that is complexly affected by the flow and the water stage in the river, it may be unreasonable to analyze the seepage safety as previous studies derived from the neglect of river flow. In this study, an experiment was conducted to investigate flow structures in a trapezoidal open-channel and the influence of the channel flow on the seepage through a levee. Flow structures in a trapezoidal open-channel were distinguished from a rectangular open-channel such as velocity and bottom shear stress distributions. In case with the flow velocity of 0.5 m/s, seepage water heads were higher 10 percent as compared with the stagnant case. This result is caused by dynamic heads, secondary currents, turbulent fluctuation forces, and various physical factors. It is suggested that external force boundary considered in terms of the flow as well as the water stage is proper to seepage analyses.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.539-540
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• 2006

• Journal of the Korea Construction Safety Engineering Association
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• s.48
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• pp.52-59
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• 2009

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.468-468
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• 2016

3차원 동수역학 모델을 이용하여 연안 순환에서 발생하는 이안류의 연직 분포를 조사하였다. 이안류 흐름은 변수심 위에서 발생하는 파의 쇄파와 모멘텀 전달에 의해 발생하는 외해방향의 흐름을 의미하는 것으로 해안의 보전, 유지 및 개발 측면에서 매우 중요한 역할을 한다. 지난 수십년동안 이안류와 관련된 현상을 해석하기 위해 많은 연구들이 수행되어 왔다. 하지만 대부분의 연구들은 수심적분된 2차원 모델을 사용하거나 위상 평균된 3차원 모델을 사용하여 이안류 흐름이 발생할 시 유속의 3차원 분포나 각 종 물리량의 시간적인 변화 등을 모의하기 어려웠다. 본 연구에서는 3차원 동수역학 모델 NHWAVE (Non-Hydrostatic WAVE model)을 이용하여 이안류의 연직분포를 조사하였다. 이안류를 발생시키기 위하여 이상적인 이안류 지형을 만들었으며 여러 지점에서 연직분포를 측정하여 수심적분된 Boussinesq 모델과 비교하여 특성을 파악하였다. 수치모의 수행결과, 두 모델 모두 이안류 현상을 잘 재현하였으나 Boussinesq 모델은 수평유속의 연직방향 변화를 잘 재현하지는 못하였다. 또한, 파고가 상대적으로 큰 경우에는 3차원 모델에서는 작은 순환류가 외해 영역에서 발생하였으나 Boussinesq 모델에서는 관측하지 못하였다.

• The Korean Journal of Physiology
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• v.21 no.2
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• pp.201-210
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• 1987

수온변화에 따른 심맥관계 및 신장기능의 변화와 생체실험을 통한 온도에 의한 adrenoceptor의 변형을 알아보기 위해, 무마취 자라에서 $18^{\circ}C$에서 $25^{\circ}C$로 수온을 증가시 나타나는 혈압, 심박동수 및 신장기능의 변화를 관찰하고, epinephrine 1 ug/kg과 10 ug/kg을 상이한 온도에 노출된 자라의 정맥내 투여하여 나타나는 효과를 비교하였다. 1) $18^{\circ}C$에서 $25^{\circ}C$로 수온을 증가시킴에 따라 심박동수는 현저히 증가하여 일정하게 유지되었으나, 혈압 및 혈장 renin 활성도는 변화하지 않았다. 온도증가에 의해 뇨량, 사구체여과율 및 전해질 배설량의 현저한 증가를 보였으나 90분부터는 서서히 감소하기 시작하였다. 2) 수온 $18^{\circ}C$에 노출된 자라에서 epinephrine은 dose-dependent한 양상으로 혈압 및 심박동수를 증가시켰으며, 다량의 epinephrine 투여시 작용시간은 현저히 연장되어 있었다. $25^{\circ}C$에 노출된 자라에서는 epinephrine에 의한 혈압상승 효과 및 심박동수 증가는 나타났으나, dose dependency나 작용시간의 차이는 발견할 수 없었다. 3) 동량의 epinephrine에 의한 혈압 및 심박동수의 증가효과는 $18^{\circ}C$와 $25^{\circ}C$에 노출된 자라에서 유의한 차이를 발견할 수 없었으나, $18^{\circ}C$에 노출된 자라에서 epinephrine의 작용시간 및 반감기가 현저히 연장되어 있었다. 4) Epinephrine 투여에 의해 뇨량, 사구체여과율 및 전해질 배설량의 증가를 관찰하였으며, 이는 dose-dependent 양상이었다. 그러나, 신장효과의 유의한 차이는 상이한 온도에 노출된 두 군에서 발견할 수 없었다. 이상의 결과로, 온도증가에 의한 이뇨 및 sodium 배설효과는 혈관이완에 의한 사구체여과율의 증가에 기인한 것으로 사료되며, 상이한 온도에 노출된 자라에서 epinephrine 효과의 차이를 발견할 수 없었던 것은 본 실험에서 가한 좁은 범위의 온도의 변화 내에서는 adrenoceptor의 변형이 나타나지 않을 것이라고 추론하였다. 그러나 저온에서의 epinephrine의 작용시간의 연장은 아마도 epinephrine의 파괴 효소의 활성도의 감소인 것으로 사료된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1B
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• pp.47-55
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• 2011

This study suggests new synthetic unit hydrograph method considering hydrodynamic characteristic on the basin. The suggested method based on width function GIUH, and the procedure is summarized as follows; 1) Draw up a travel distance distribution map (width function) which is raster of length between from center of individual cells to the outlet by GIS. 2) Calculation of travel time distribution map (rescaled width function) by hydrodynamic parameters and travel distance distribution map. 3) Derivation of IUH and Duration UH from rescaled width function. 4) Comparison of shape of UH between suggested method and existing synthetic unit hydrograph methods. The target basins are selected Ipyeong and Tanbu subwatershed in the Bocheong Basin. The target basins are similar scale (watershed area), but different drainage structure (drainage density et al.). Therefore we anticipate that there are different hydrologic response functions because different hydrodynamic characteristics. As a result of derivation of UH, existing synthetic unit hydrograph methods are similar shape of UHs about Ipyeong and Tanbu watersheds, but the suggested method is different shape of ones. As a result of application to observed data, the peak discharge by suggested method is similar to existing synthetic unit hydrograph methods, but the peak time is well correspondence between those. Henceforth, if the suggested method combines with the rational velocity estimation method, it is useful method for synthetic of UH in ungauged watershed.

• 건강소식
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• v.35 no.5
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• pp.38-39
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• 2011

아직 봄을 시샘하는 겨울의 마지막 바람이 불던 지난 3월 21일 동수원 우체국에서는 접수한 고객들이 창구가 아닌 임시로 마련된 건강체험 데스크에 줄을 서 있었다. 한국건강관리협회가 우정사업본부와 함께 우체국 방문 고객 및 상주직원을 대상으로 올바른 건강관리에 대한 홍보와 간단한 건강체험 서비스를 제공하기 때문이다. 이 행사는 지난해 이어 올해 두 번째 열린 것이다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.6
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• pp.437-449
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• 1991

Time series of barometrically adjusted sea level at Pusan, Izuhara and Hakada are analyzed to study the fluctuations of the Tsushima Current through the Korea Strait. Variability of sea levels and their differences is divided into two parts with respect to the frequency of 0.01 or 0.02 cycles per day(cpd) At lower frequency, both of sea levels and sea level difference(SLD) are coherent and in phase to each other. Pusan has smaller seasonal variations in sea level than other two stations because the effects of geostrophic current and prevailing wind have a negative influence on the seasonal thermosteric contribution to sea level change. Low frequency variability of SLD thus of the Tsushima Current is much greater in the western channel. For higher frequency parts, SLD in the eastern channel has larger variability and is not coherent with that of the western channel. Sea levels at Pusan and Izuhara are $180^{\circ}$ out of phase with SLD in the western and eastern channel respectively, whereas the Hakada level is in phase. This result indicates that eastern channel has a normal response to the along-channel winds and cross-channel geostrophy because Izuhara faces the eastern channel.