• 한국방재학회 논문집
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• 제8권3호
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• pp.149-155
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• 2008

사석의 안정성 분석을 위해 Isbash식, California 도로국식, Netherlands간이식, ASCE식, Pilarczk식, Maynord식의 검토를 수리모형실험을 통해서 수행하였다. 사석의 경우는 직경과 중량이 커질수록 한계유속이 크게 나왔으며, 그에 따른 수심에 대한 사석의 직경비, Froude수, 평균유속에 따른 전단유속비, Shields수는 상관성이 크게 나왔다. 공칭직경에 대한 안정식은 6가지 식이 모두 크게 산정하고 있고, 그중 미 공병단에서 제시한 Maynord식이 비교적 잘 맞는 것으로 나타났다. 중량산정식의 경우 Isbash식, Netherlands식, Pilarczk식은 중량이 유속에 대하여 과대추정 되었고, 켈리포니아주 정부 도로국 식이 실험결과와 일치하는 것으로 나타났다. 단위중량이 작은 석고재료에 의한 모형사석 실험에서는 형상계수가 클수록 한계유속이 크게 나타났고, 또한 임의배열일 때보다 규칙배열일 경우 한계유속이 크게 측정 되었다. 이로서 형상계수와 결속의 정도가 사석의 안정성에 중요한 함수라는 것을 알 수 있다.

• 한국전자파학회논문지
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• 제23권6호
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• pp.669-681
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• 2012

본 논문에서는 헬리컬 코일을 이용하는 공진형 무선 전력 전송 시스템에서 새로운 상호 인덕턴스 계산식을 이용한 해석적 계산을 제안한다. 상호 인덕턴스 계산 과정 중에 중요한 변수의 look-up table을 수식화 하였다. 송 수신이 대칭인 구조에서 두 헬리컬 코일 간의 거리를 53 mm부터 500 mm까지 10 mm 간격으로 거리를 증가시키며, 공진 주파수와 삽입 손실에 대한 계산 결과와 실험 결과를 비교하였다. 실험 결과와 계산 결과의 공진 주파는 평균적으로 5.63 %의 차이를 보였다. 삽입 손실은 실험 결과와 290 mm에서 0.33 dB의 가장 작은 차이를 보였고, 평균적으로 2.25 dB의 차이를 보였다. 발룬을 사용하지 않았을 때의 실험 결과가 계산 결과와 더 근접한 결과를 보이는 것을 확인했다.

• 대한본초학회지
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• 제30권3호
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• pp.49-54
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• 2015

Objectives : This study investigated the neuroprotective effect of Gastodia Rhizoma-gamibang (GG) water extracts against scopolamine-induced neurotoxicity in the hippocampus of male Sprague-Dawley rats. Methods : The animals were divided into five different groups with six animals per each group. The normal group (Nor) was administered with saline, while the control group (Con) was administered with saline after scopolamine treatment. The experimental group (Exp) was administered orally GG extracts at doses of 200 mg/kg (GG1 group), 400 mg/kg (GG2 group), 1000 mg/kg (GG5 group) for 30 day after scopolamine treatment. Results : From a light microscopy study, the nuclei of neurons and glial cells in the hippocampus were more shrunken or condensed in the 30 day control group compared with normal group. In the experimental groups, proportional to the dose, recovered from neurotoxicity induced by scopolamine. The control group, the density of hippocampal neurons were reduced 17-20% compared to normal group. The densities of neurons from the CA1, and CA3 area of the hippocampus in the GG1, GG2 and GG5 groups significantly increased compared with the Con. In the experimental group, neuronal cells are recovered from scopolamine-induced damage. A number of glial cells are observed increase from GG2 and GG5 groups. The PAS-positive materials in the tissues hippocampus), was lower in the Exp than the Con. Conclusions : The present study demonstrates that Gastodia Rhizoma-gamibang extract reduces neuronal damage in the hippocampus of scopolamin-induced impairment mice.

• Structural Engineering and Mechanics
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• 제74권3호
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• pp.395-406
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• 2020

Many prefabricated concrete frame joints have been proposed, and most of them showed good seismic performance. However, there are still some limitations in the proposed fabricated joints. For example, for prefabricated prestressed concrete joints, prefabricated beams and prefabricated columns are assembled as a whole by the pre-stressed steel bar and steel strand in the beams, which brings some troubles to the construction, and the reinforcement in the core area of the joints is complex, and the mechanical mechanism is not clear. Based on the current research results, a new type of fabricated joint of prestressed concrete beams and confined concrete columns is proposed. To study the seismic performance of the joint, the quasi-static test is carried out. The test results show that the nodes exhibit good ductility and energy dissipation. According to the experimental fitting method and the "fixed point pointing" law, the resilience model of this kind of nodes is established, and compared with the experimental results, the two agree well, which can provides a certain reference for elasto-plastic seismic response analysis of this type of structure. Besides, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• 대한한의학방제학회지
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• 제31권4호
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• pp.373-388
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• 2023

Objectives : This study aimed to provide basic data for research by investigating non-clinical experimental studies on herbal medicines and its compounds for precocious puberty. Methods : A search was conducted for all literature until October 2023 using combinations of keywords such as precocious puberty, puberty, and chinese medicine in three databases (Pubmed, OASIS, and ScienceON). Results : 1. In animal experiments, studies were mainly conducted using a model that induced precocious puberty by subcutaneously administering danazol to SD rats on the 5th day after birth, and in cell experiments, precocious puberty was induced by treating GT1-7 cells with kisspeptin 10 or estradiol. 2. Anemarrhenae Rhizoma, Phellodendri Cortex, and Prunellae Spica were mainly used as herbal medicine to evaluate their efficacy on precocious puberty in non-clinical experiments. 3. Macroscopic observation, hematological analysis, histological analysis, and genetic analysis were performed as methods to analyze the experimental results. Conclusions : In this study, the effects of herbal medicine on precocious puberty and non-clinical research methods were confirmed. Based on the results of this study, it is expected that non-clinical effectiveness and mechanism research on materials that are clinically effective in Traditional Korean Medicine will be revitalized.

• 한국철도학회논문집
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• 제3권4호
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• pp.194-202
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• 2000

Fatigue behavior of shear joints between the combined reinforced concrete(RC) and the reinforced steel fiber concrete(SFRC) specimens has been experimentally investigated. Experimental parameters used are the amount of steel fiber and the type of shear joint. Six specimens have been tested under static load, and eight specimens have been subjected to the fatigue load in a range of 50 % and 5 % of the ultimate static load. The purpose of this research is to propose an empirical formula for fatigue shear behavior of the combined RC and SFRC structures on the basis of experimental result. It can be observed from experimental results that addition of steel fibers to concrete specimen increases the static ultimate load by approximately 25 %, enhances the fatigue behavior, and also reduces vertical and lateral displacements at the shear joint for a given load cycle after the occurrence of first crack.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.110-117
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• 2004

The aim of a benchmark study is carried out nine methods are employed for ULS analysis which implicitly predict the ultimate strength of aluminium stiffened panels under axial compression. For this purpose, DNV PULS, experimental and numerical data on the ultimate strength of panels were collected. Comparison of these experimental / numerical, DNV PULS / numerical, results with theoretical solutions by the candidate methods is performed. Also it's compared that ALPS/ULSAP program is based on closed-form formula for the ULS of plates and grillages under axial compression. It is considered that ALPS/ULSAP methodology provides quite accurate and reasonable ULS calculations by a comparison with more refined FEA. Comparison of these experimental data, numerical, computational software results with the simplified solutions obtained by the candidate methods is then performed. The model uncertainties associated with the candidate methods are studied in terms of mean bias and COV (i.e., coefficient of variation) against experiments and numerical solutions, and the relative performance of the various methods is discussed.

• 한국소음진동공학회논문집
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• 제21권6호
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• pp.491-498
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• 2011

The structural vibration due to earthquake or outside impact causes serious problem for building safety. A dynamic model of a friction damper which can be constructed and installed easily is needed to reduce the vibration of the building. In this paper, the experimental equation of a circular friction damper is derived and designed for reduction of a earthquake vibration of a building. The developed experimental equation is defined to simply design the capacity on design of the circular friction damper based on the results of the performance test. Finally this experimental equation can be used for the design of a circular friction damper.

• Journal of Mechanical Science and Technology
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• 제18권10호
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• pp.1849-1858
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• 2004

For examining friction-factor characteristics of round-hole pattern surfaces which are usually applied on damper seals, flat plate test apparatus is designed and fabricated. The measurement method of leakage and pressure distribution along round-hole pattern specimen with different hole area is described and a method for determining the Fanning friction factor is discussed. Results show that the round-hole pattern surfaces provide a much larger friction factor than smooth surface, and the friction factor vs. clearance behavior yields that the friction factor generally decreases as the clearance increases unlike the results of Nava's flat plate test. As the hole depth is decreased, the friction factor is increased, and maximum friction factor is obtained for 50% of hole area. Since the present experimental friction factor results show coincident characteristics with Moody's friction factor model, empirical friction factors for round-hole pattern surfaces are obtained by using the Moody's formula based on curve-fit of the experimental data. Results of Villasmil's 2D CFD simulation support the present experimental test result.

• 한국해양공학회지
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• 제18권4호
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• pp.8-14
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• 2004

Pneumatic damping through an orifice-type duct for an OWC-type wave energy device is studied experimentally. Forced oscillation tests are used to measure chamber pressure and velocity of air-flow through an orifice. Pneumatic damping coefficients are deducted from the experimental research, and the influence of frequency, heave amplitude, and orifice size are discussed. Finally, two formulas are proposed for the estimation of non-dimensional pneumatic damping coefficient by regression analysis. The proposed formula proves to be a reliable method for practical application.