• 자원환경지질
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• 제27권6호
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• pp.579-592
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• 1994

A case study is presented where a fluvial system is modeled in three dimensions and compared to data gathered from a study of the Arkansas River. The data is unique in that it documents changes that affected a straight channel that was excavated within the river by the U.S. Army Corps of Engineers. Excavation plan maps and sequential aerial photographs show that the channel underwent massive deposition and channel migration as it returned to a more natural, meandering path. These records illustrate that stability of fluvial system can be disrupted either by catastrophic events such as floods or by subtle events such as the altering of a stream's equilibrium base level or sediment load. SEDSIM, Stanford's Sedimentary Basin Simulation Model, is modified and used to model the Arkansas River and the geologic processes that changed in response to changing hydraulic and geologic parameters resulting from the excavation of the channel. Geologic parameters such as fluid and sediment discharge, velocity, transport capacity, and sediment load are input into the model. These parameters regulate the frequency distribution and sizes of sediment grains that are eroded, transported and deposited. The experiments compare favorably with field data, recreating similar patterns of fluid flow and sedimentation. Therefore, simulations provide insight for understanding and spatial distribution of sediment bodies in fluvial deposits and the internal sedimentary structure of fluvial reservoirs. These techniques of graphic simulation can be contributed to support the development of the new design criteria compatible with natural stream processes, espacially drainage problem to minimize environmental disruption.

• 한국항공우주학회지
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• 제33권3호
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• pp.39-46
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• 2005

본 논문에서는 광범위한 함수 근사성질을 갖고 있는 신경회로망을 이용하여, 시스템의 입출력 조화성분의 선형관계를 표현하기 위해 추정된 전달행렬의 적용범위를 확장할 수 있는 적응 고차조화제어(Higher Harmonic Control, HHC) 기법을 제안하고 있다. 신경회로망의 학습신호는 추정된 전달행렬을 기반으로 계산된 최적제어 이득 값 행렬을 이용하여 구성된다. 내부 안정성을 보장하기 위하여 신경회로망의 가중치 학습방법은 Lyapunov 직접 방법을 이용하여 유도하였다. 6개의 입력과 2개의 출력을 갖는 비선형 시스템에 대한 시뮬레이션 결과를 통해 적응 고차조화제어 기법이 불확실한 전달행렬에 적용 가능함을 보였다.

• 한국안전학회지
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• 제19권1호
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• pp.117-123
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• 2004

본 연구는 셀룰로스 기반의 복합소재에서의 수분 흡수에 의한 뒤틀림 변형효과를 위하여 변형된 고전 선형 적층판 이론을 바탕으로 실험에 의한 반복 데이터 분석 방법과 수치해석의 방법을 이용하여 연구하였다. 실험적 모델은 Moire Interferometer에 따라 수분 생성, 변형과 변형률 모델을 구현하였으며, 실험에 쓰여진 재료는 셀룰로이드 강화 에폭시를 적층한 재료를 사용하였다. 이러한 수치해석에서 제시된 방법으로 내부응력 변화에 따른 변형의 안정성 모델의 평가 툴을 개발하고, 예측모델을 구현할 수 있다.

• 웰빙융합연구
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• 제1권1호
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• pp.1-13
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• 2018

It has become a request of the time that multicultural population and multicultural education have become an issue and a subject of interest in the Korean society. The numbers of foreigners and multicultural families such as international marriage families and foreign worker families living in Korea are increasing, which have resulted in a geometrical increase in the number of multicultural families' children attending school. This leads an assumption that discrimination in terms of race, gender, religion, and culture can occur in school settings and the children of multicultural families are prone to become the targets of group bullying and school violence. This study first examined the current policy of multicultural education in Korea and reviewed the meanings and necessity of multicultural counseling above multicultural education. Second, this study classified and reviewed the applicability of the policy of multicultural education into multicultural education sites by groups. Third, this study selected and organized the increasing demands for multicultural counseling and assignments to effectively respond to them. Interest toward the children of multicultural families and counseling have increased with more researches on multicultural families. It will be thus necessary to accumulate more studies on multicultural counseling and ensure internal stability of multicultural-related businesses.

• 한국물환경학회지
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• 제18권2호
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• pp.141-150
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• 2002

Two-stage membrane bioreactor using submerged hollow fiber membrane was applied in laboratory scale to treat nitrogen and phosphorus of domestic wastewater. Alum as the flocculant and adsorbent was added into the anaerobic basin of two-stage membrane bioreactor and mixed liquid of aerabic basin was recycled to the anaerobic basin for the purpose of nitrogen removal. Experiment was carried out to find removal efficient of phosphorous and nitrogen components in the mixed liquid, and the stability of the permeate flux and pressure of two-stage membrane bioreactor. In case of alum was added as the flocculant and adsorbent into the anaerobic basin, soluble phosphorus removal efficient was relatively higher and total permeate resistance(Rtot) was more increased out nitrogen removal efficient was lower as the result of lack of alkalinity and insufficient nitrification process than the case of alum was not added.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.799-804
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• 2001

Nonlinear normal mode (NNM) vibration, in a nonlinear dual mass Hamiltonian system, which has 6th order homogeneous polynomial as a nonlinear term, is studied in this paper. The existence, bifurcation, and the orbital stability of periodic motions are to be studied in the phase space. In order to find the analytic expression of the invariant curves in the Poincare Map, which is a mapping of a phase trajectory onto 2 dimensional surface in 4 dimensional phase space, Whittaker's Adelphic Integral, instead of the direct integration of the equations of motion or the Birkhotf-Gustavson (B-G) canonical transformation, is derived for small value of energy. It is revealed that the integral of motion by Adelphic Integral is essentially consistent with the one obtained from the B-G transformation method. The resulting expression of the invariant curves can be used for analyzing the behavior of NNM vibration in the Poincare Map.

• 국제물리치료학회지
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• 제10권2호
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• pp.1791-1796
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• 2019

Background: Vibration exercise after ankle surgery improves proprioception and ankle muscle strength through vibration stimulation. Objective: To examine the effects of vibration exercise on the ankle stability. Design: Randomized controlled clinical trial (single blind) Methods: Twenty soccer players were randomly divided into experimental group and control group. The Vibration exercise program was conducted 12 weeks and 3 times a week. Ankle joint proprioceptive sensory test and Isokinetic muscle strength test were performed using Biodex system pro III to measure plantar flexion / dorsiflexion and eversion / inversion motion. Results: The result of isokinetic test of ankle joint is showed significant improvement in all measurement items, such as leg flexion, lateral flexion, external and internal muscle forces, compared to previous ones by performing vibration movements for 12 weeks. However, in the comparison group, plantar flexor ($30^{\circ}$), eversion muscle ($120^{\circ}$), inversion ($30^{\circ}$) of limb muscle strength were significantly improved compared with the previous phase; was no significant difference in dorsi-flexion. There was no significant difference between groups in all the items. Conclusions: In this study, we analyzed the effects of rehabilitation exercise on soccer players who had reconstructed with an ankle joint ligament injury through vibration exercise device. As a result, we could propose an effective exercise method to improve the ability, and confirmed the applicability as an appropriate exercise program to prevent ankle injuries and help quick return.

• Mass Spectrometry Letters
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• 제10권3호
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• pp.88-92
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• 2019

A sensitive analytical method of rhodanthpyrone A in rat plasma was developed using a liquid chromatography-tandem mass spectrometry (LC-MS/MS). Rhodanthpyrone A and rhodanthpyrone B (internal standard) in rat plasma were extracted by a liquid-liquid extraction method with ethyl acetate. This extraction method gave results in high and reproducible extraction recovery in the range of 73.75-79.90% with no interfering peaks around the peak elution time of rhodanthpyrone A and B. The standard calibration curves for rhodanthpyrone A ranged from 0.5 to 2000 ng/mL were linear with $r^2$ > 0.994 and the inter- and intra-day accuracy and precision and the stability were within acceptance criteria. Using this validated analytical method, pharmacokinetics of rhodanthpyrone A following intravenous and oral administration of rhodanthpyrone A at doses of 2 mg/kg and 30 mg/kg, respectively, were investigated. Rhodanthpyrone A in rat plasma showed multi-exponential elimination pattern with high clearance and volume of distribution values. The absolute oral bioavailability of this compound was calculated as 3.7%. Collectively, the newly developed sensitive LC-MS/MS analytical method of rhodanthpyrone A could be successfully applied to investigate the pharmacokinetic properties of this compound and would be useful for the further studies on the efficacy, toxicity, and biopharmaceutics of rhodanthpyrone A.

• 한국염색가공학회지
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• 제33권3호
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• pp.161-167
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• 2021

Polymer nanocomposite is considered a great alternative to solve the limitations that exist in a simple combination material, as well as to produce multifunctional and high-performance results. In this research, PVA/bentonite nanocomposite films were prepared based on the presence or absence of modification of nano-clay(bentonite) a SUPERGEL^® product, modification conditions and content, and the structural variation of the prepared PVA/bentonite nanocomposite films were examined. The effect of variations in the internal structure of the nanocomposite on mechanical and thermal properties was investigated. As a result of evaluating the thermal characteristics of the PVA/bentonite nanocomposite film based on the concentration of the modified bentonite, it was verified that the thermal characteristics and stability were improved because of interaction between the polymer and the modified nano-clay.

• 한국표면공학회지
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• 제54권2호
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• pp.43-52
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• 2021

The Ni-based superalloy, Inconel 740, was corroded between 800 and 1100℃ for up to 100 hr in air and Ar-0.2%SO₂ gas in order to study its corrosion behavior in air and sulfur/oxygen environment. It displayed relatively good corrosion resistance in both environment, because its corrosion was primarily dominated by not sulfidation but oxidation especially in Ar-0.2%SO₂ gas. Such was attributed to the thermodynamic stability of oxides of alloying elements when compared to corresponding sulfides. The scales consisted primarily of Cr₂O₃, together with some NiAl₂O₄, MnCr₂O₄, NiCrMnO₄, and rutile-TiO₂. Sulfur from SO₂ gas made scales prone to spallation, and thicker. It also widened the internal corrosion zone when compared to air. The corrosion resistance of IN740 was mainly indebted to the formation of protective Cr₂O₃-rich oxides, and suppression of the sulfide formation.