• Wind and Structures
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• 제18권3호
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• pp.235-252
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• 2014

An effective numerical technique to calculate the reactions of a multi-spanned transmission line conductor system, under arbitrary loads varying along the spans, is developed. Such variable loads are generated by High Intensity Wind (HIW) events in the form of tornadoes and downburst. First, a semi-closed form solution is derived to obtain the displacements and the reactions at the ends of each conductor span. The solution accounts for the nonlinearity of the system and the flexibility of the insulators. Second, a numerical scheme to solve the derived closed-form solution is proposed. Two conductor systems are analyzed under loads resulting from HIW events for validation of the proposed technique. Non-linear Finite Element Analyses (FEA) are also conducted for the same two systems. The responses resulting from the technique are shown to be in a very good agreement with those resulting from the FEA, which confirms the technique accuracy. Meanwhile, the semi-closed form technique shows superior efficiency in terms of the required computational time. The saving in computational time has a great advantage in predicting the response of the conductors under HIW events, since this requires a large number of analyses to cover different potential locations and sizes of those localized events.

• 한국동물학회:학술대회논문집
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• 한국동물학회 2001년도 한국생물과학협회 학술발표대회
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• pp.228.2-228
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• 2001

No Abstract, See Full Text

• 한국환경과학회지
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• 제32권4호
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• pp.221-232
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• 2023

This study investigated the antioxidant effect of Hermetia illucens larvae using different extraction temperatures and solvents. We found significant differences in total phenolic content (TPC), total flavonoid content (TFC), an in three antioxidant indexes 2,2-diphenyl-1-picrylhydrazyl (DPPH), 1,1'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and ferric-reducing antioxidant power (FRAP) contents, among the samples depending on the extraction temperature and solvent used. The sample extracted with water at 45℃ (HIW-45℃) showed the highest TPC, DPPH, ABTS, and FRAP contents, while the sample extracted with water at 90℃ (HIW-90℃) showed the highest TFC. These differences can be due to the different chemical structures of the extracted components. Based on these results, HIW-45℃ was the optimal extraction method for Hermetia illucens. We intend to further investigate the availability of functional materials for Hermetia illucens using this method.

• Wind and Structures
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• 제37권6호
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• pp.413-423
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• 2023

Wind turbines are usually steel hollow structures that can be vulnerable to dramatic failures due to high-intensity wind (HIW) events, which are classified as a category of localized windstorms that includes tornadoes and downbursts. Analyzing Wind Turbines (WT) under tornadoes is a challenging-to-achieve task because tornadoes are much more complicated wind fields compared with the synoptic boundary layer wind fields, considering that the tornado's 3-D velocity components vary largely in space. As a result, the supporting tower of the wind turbine and the blades will experience different velocities depending on the location of the event. Wind farms also extend over a large area so that the probability of a localized windstorm event impacting one or more towers is relatively high. Therefore, the built-in-house numerical code "HIW-WT" has been developed to predict the straining actions on the blades considering the variability of the tornado's location and the blades' pitch angle. The developed HIWWT numerical model incorporates different wind fields that were generated from developed CFD models. The developed numerical model was applied on an actual wind turbine under three different tornadoes that have different tornadic structure. It is found that F2 tornado wind fields present significant hazard for the wind turbine blades and have to be taken into account if the hazardous impact of this type of unexpected load is to be avoided.

• 대기
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• 제21권1호
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• pp.1-16
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• 2011

Numerical prediction capability has been improved over the decades, but progress of prediction for high-impact weather (HIW) was unsatisfactory. One reason of low predictability for HIW is lack of observation data. The National Institute of Meteorological Research (NIMR) has been performed observation program for improvement of predictability, and reduction in social and economical cost for HIW. As part of this observation program, summer intensive observation program (ProbeX-2009) was performed at the observation-gap areas from 25 August to 6 September 2009. Sounding observations using radiosonde were conducted in the Gisang2000 research vessel (R/V) from the Korea Meteorological Administration (KMA) over the West Sea and the Eardo R/V from the Korea Ocean Research and Development Institute (KORDI) over the South Sea. Observation System Experiment (OSE) is carried out to examine the effect of ProbeX-2009 data. OSEs using Korea Local Analysis and Prediction System (KLAPS) and Weather Research and Forecasting (WRF) Model are conducted to investigate the predictability for a short time forecast. And, OSEs using WRF/3DVAR system and WRF forecast model are conducted to study the predictability for an extended time. Control experiment (K_CTL and CNTL) used only GTS observation and experiment (K_EXP and SWEXP) used ProbeX-2009 data from two system are performed. ETS for 3hr accumulated rainfall simulated by KLAPS-WRF shows that K_EXP is higher than K_CTL. Also, ETS for 12hr accumulated rainfall of SWEXP from 3DVAR-WRF is higher than CNTL. The results indicate that observation over the ocean has positive impact on HIW prediction.

• Wind and Structures
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• 제22권1호
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• pp.65-87
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• 2016

The wind velocity profile over the height of a structure in high intensity wind (HIW) events, such as downbursts, differs from that associated with atmospheric boundary layer (ABL) winds. Current design codes for lattice transmission structures contain only limited advice on the treatment of HIW effects, and structural design is carried out using wind load profiles and response factors derived for ABL winds. The present study assesses the load-deformation curve (capacity curve) of a transmission tower under modeled downburst wind loading, and compares it with that obtained for an ABL wind loading profile. The analysis considers nonlinear inelastic response under simulated downburst wind fields. The capacity curve is represented using the relationship between the base shear and the maximum tip displacement. The results indicate that the capacity curve remains relatively consistent between different downburst scenarios and an ABL loading profile. The use of the capacity curve avoids the difficulty associated with defining a reference wind speed and corresponding wind profile that are adequate and applicable for downburst and ABL winds, thereby allowing a direct comparison of response under synoptic and downburst events. Uncertainty propagation analysis is carried out to evaluate the tower capacity by considering the uncertainty in material properties and geometric variables. The results indicated the coefficient of variation of the tower capacity is small compared to those associated with extreme wind speeds.

• 생명과학회지
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• 제15권3호
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• pp.453-460
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• 2005

담배의 생장과 광합성 색소 및 효소에 대한 카드뮴의 독성과 이에 대한 칼슘의 영향을 연구하였다. 카드뮴에 의한 생장과 엽록소 수준에서의 억제 현상은 칼슘에 의해 회복되었다. 특히, 엽록소의 함량은 카드뮴만 처리한 것 보다 카드뮴과 칼슘을 같이 처리하였을 때 현저하게 증가하였다. 또한 rubisco의 활성과 함량은 카드뮴을 처리한 것 보다 처리하지 않았을 때 현저하게 감소하였으며, 카드뮴의 이러한 효과는 칼슘에 의해 환원되었다. Rubisco activase의 활성과 함량도 rubisco와 같은 경향을 보였다. Rubisco에서 카드뮴과 칼슘에 의해 유도되는 이와 같은 변화는 rubisco activase에 의해 기인됨을 의미한다.

• 한국가금학회지
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• 제37권4호
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• pp.331-336
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• 2010

We evaluated the immunomodulatory effects of proanthocyanidin-rich extract (PAE) from Pinus radiata bark in broiler. Proliferation of peripheral blood mononuclear cells and thymocytes was significantly enhanced in 2.5, 5, 10 mg/kg PAE-treated broiler chickens. Proliferation of splenocytes was significantly enhanced in 1.25, 2.5, 5, 10 mg/kg PAE-treated broiler chickens. These effects were markedly enhanced by the presence of LPS, which acts on B cells responsible for humoral immunity, and Con A, which acts directly on T cells involved in cell mediated immunity. PAE significantly promoted the expression of interleukin-18 and interleukin-$1\beta$. Thus, PAE from P. radiata possesses immunomodulatory effects in broiler chickens.

• Wind and Structures
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• 제29권5호
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• pp.339-359
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• 2019

Pre-stressed concrete poles are among the supporting systems used to support transmission lines. It is essential to protect transmission line systems from harsh environmental attacks such as downburst wind events. Typically, these poles are designed to resist synoptic wind loading as current codes do not address high wind events in the form of downbursts. In the current study, the behavior of guyed pre-stressed concrete Transmission lines is studied under downburst loads. To the best of the authors' knowledge, this study is the first investigation to assess the behaviour of guyed pre-stressed concrete poles under downburst events. Due to the localized nature of those events, identifying the critical locations and parameters leading to peak forces on the poles is a challenging task. To overcome this challenge, an in-house built numerical model is developed incorporating the following: (1) a three-dimensional downburst wind field previously developed and validated using computational fluid dynamics simulations; (2) a computationally efficient analytical technique previously developed and validated to predict the non-linear behaviour of the conductors including the effects of the pretension force, sagging, insulator's stiffness and the non-uniform distribution of wind loads, and (3) a non-linear finite element model utilized to simulate the structural behaviour of the guyed pre-stressed concrete pole considering material nonlinearity. A parametric study is conducted by varying the downbursts locations relative to the guyed pole while considering three different span values. The results of this parametric study are utilized to identify critical downburst configurations leading to peak straining actions on the pole and the guys. This is followed by comparing the obtained critical load cases to new load cases proposed to ASCE-74 loading committee. A non-linear failure analysis is then conducted for the three considered guyed pre-stressed concrete transmission line systems to determine the downburst jet velocity at which the pole systems fail.

• 한국임상수의학회지
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• 제21권1호
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• pp.45-48
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• 2004

5년령의 암컷 히말라얀 고양이가 복막심낭횡격막 허니아가 의심되어서 건국대학교 수의과대학 부속 동물병원에 내원하였다. 일련의 검사를 실시한 후 환자는 복막심낭횡격막 허니아와 간기능 부전이 확진되었다. 그 후 한 달간의 약물치료에도 불구하고, 혈청화학검사에서 간효소 (aspartate transferase, alanine transferase, gamma-glutamyl transferase) 수치는 정상범위로 내려 가지 않았다. 이 환자는 수술 중에 간 일부가 횡격막에 유착되어서 괴사가 일어난 것이 발견되었고, 유착되고 괴사된 간 조직은 횡격막에서 조심스럽게 분리하여 절제하였다. 횡격막은 괴사된 부분을 잘 정리하고 난 뒤에 손상된 횡격막 부분을 simple continuous suture pattern으로 봉합하였다. 수술 후 한 달 뒤 환축은 정상적인 상태를 보였고 다른 복합증 없이 회복되었다. 그리고 혈청화학 수치 중 간효소 수치도 정상 범위로 떨어졌다.