• International Journal of Human Ecology
• /
• 제15권2호
• /
• pp.69-80
• /
• 2014

Guided by the exchange model, altruistic model, intergenerational solidarity theory, and cultural contexts, this study explored the determinants of financial intergenerational transfers between older parents and adult children in South Korea. We examined 18,820 parent-child dyads by using random-effects models on the first wave of the Korean Longitudinal Study of Ageing (KLoSA) data. Findings showed that downward financial intergenerational transfers were consistent with the self-interest exchange model but upward transfers did not support microeconomic theories. Family solidarity theory was generally supported by downward transfers but geographical proximity was not positively associated with upward transfers. Lastly, cultural contextual variables such as marital status, birth order, and sex of a child were found to be significant. Parents tended to both provide and receive more financial support from unmarried children than from married children. Within the same marital status, the hierarchy existed in order of the first-born son, the second or later sons, and daughters when it came to downward financial transfers. Regarding upward financial transfers, the preference in order was more complicated. The findings of this study help in understanding the intergenerational financial transfers in the Korean context.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2003년도 춘계학술대회 논문집
• /
• pp.214-214
• /
• 2003

During a model test of Hutton TLP, a "ringing" response was first observed about 20 years ago. This phenomenon is a resonant build up over the time of wave period and this burst-like motion can cause the extreme load on the TLP tether. It is often detected in the large and steep irregular waves but the generation mechanism leading to the "ringing" is not yet well understood. According to the research since then, the higher order harmonic components may account for the "ringing" on the floating offshore structures. The main purpose of the present research is, thus, to measure the higher harmonic forces exerted on a vertical truncated circular column and to compare them with available data. A vertical truncated cylinder with a diameter of 3.5inch and a draft of 10.5inch is used as a test structure, which is a scaled model of ISSC TLP column. The cylinder is installed at a distance of 45ft from the wave maker in order to avoid parasitic waves created in the wave flap. Attached to the upper part of the cylinder are two force gages to measure the horizontal (surge) and vertical (heave) forces on the cylinder. The incoming waves are Stokes waves with a slope ranging from 0.06 to 0.24. The forces and waves are measured for 60 seconds with a sampling rate of 50 Hz. Among the recorded data, the first 10 waves are excluded because of transient behavior of the waves and the next The horizontal and vertical forces are analyzed up to 5th order harmonics. The horizontal forces are then compared to the values from the theoretical model called "FNV model". In addition, force transfer functions are also investigated. Major findings in this research are below. 1) The first order forces measured are slightly larger than the theoretical values of "FNV model" 2) The "FNV model" considerably overpredicts the second order forces. 3) The larger the amplitude and more extreme the wave slope, the smaller the predictions are compared to the experimental. 4) The higher harmonic forces are significantly smaller than the first harmonic force for all wave parameters. 5) The normalized forces vs. waves slopes are almost constant in the lower harmonics but vary a lot in the higher harmonics. 6) The trend of forces is more nonlinear in the horizontal forces than in the vertical forces as the wave slope increases. 7) The part of the results above is also observed by other researchers and confirmed again through the present work.

• 생태와환경
• /
• 제39권4호통권118호
• /
• pp.450-461
• /
• 2006

본 연구에서는 pH 5.5에서 연안퇴적물내 납과 카드뮴의 흡착 동력학을 실험실규모의 회분식 반응기를 이용하여 조사하였다. 4종류의 모델: 단일영역 물질전달모델 (one-site mass transfer model, OSMTM), 겉보기 1차속도모델 (pseudo-first-order kinetic model, PFOKM), 겉보기 2차속도모델 (pseudo-second-order kinetic model, PSOKM)과 두영역 1차속도모델 (two compartment first-order kinetic model, TCFOKM)을 사용하여 흡착속도를 분석하였다. 관련된 모델매개변수의 수에서 기대되듯이 변수가 3개인 TCFOKM이 변수가 2개인 OSMTM, PFOKM, PSOKM 보다 흡착속도를 더 잘 표현할 수 있었다. 납과 카드뮴의 대부분의 흡착은 초기 3시간 이내에 빠르게 완료되었으며, 이후 기간 동안은 느린 흡착이 이루어졌다. 모든 모델에서 겉보기 흡착평형농도($q_{e,s}$)는 퇴적물의 양이온 교환능 (CEC)과 표면적이 증가함에 따라 증가하는 것으로 예측되었으며, 이는 초기 중금속 투여 농도와 중금속 및 퇴적물의 형태와 무관하였다. OSMTM에서의 흡착속도 상수 ($k_s,\;hr^{-1}$)는 퇴적물의 CEC와 표면적이 증가함에 따라 증가하였다. PFOKM의 겉보기 1차흡착속도상수 ($k_{p1,s},\;hr^{-1}$)는 퇴적물의 특성과 관련이 없었다. PSOM 분석결과 겉보기 2차흡착속도상수 ($k_{p2,s},\;g\;mmol^{-1}\;hr^{-1}$)와 초기흡착속도 ($v_{o,s},\;mg\;g^{-1}\;hr^{-1}$)는 퇴적물의 특성과 연관되지 않았다. TCFOKM의 빠른 흡착영역의 분율($f_{1,s}$)은 수용액상의 초기농도와는 무관하게 퇴적물의 CEC와 표면적이 증가함에 따라 증가하였다. 빠른 부분에서의 흡착속도 상수 ($k_{1,s}=10^{0.1}-10^{1.0}\;hr^{-1}$)는 느린 부분에서의 흡착속도 상수 ($k_{2,s}=10^{-2}-10^{-4}\;hr^{-1}$)보다 훨씬 더 큰 것으로 나타났다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집B
• /
• pp.579-584
• /
• 2000

Algebraic Reynolds Stress (ARS) model is applied in order to analyze the turbulent flow of wall-attaching offset jet and to evaluate the model's predictability. The applied numerical schemes are upwind scheme and skew-upwind scheme. The numerical results show good prediction in first order calculations (i.e., reattachment length, mean velocity, pressure), while they show slight deviations in second order (i.e., kinetic energy and turbulence intensity). By comparison with the previous results using $k-{\varepsilon}$ model, ARS model predicts better than the standard $k-{\varepsilon}$ model, however, predicts slightly worse than the $k-{\varepsilon}$ model including the streamline curvature modification. Additionally this study can reconfirm that skew-upwind scheme has approximately 25% improved predictability than upwind scheme.

• 대한기계학회논문집B
• /
• 제24권12호
• /
• pp.1615-1624
• /
• 2000

Algebraic Reynolds Stree (ARS) model is applied in order to analyze the turbulent flow of wall-attaching offset jet and to evaluate the predictability of model. The applied numerical schemes are the upwind scheme and the skew-upwind scheme. The numerical results show a good prediction in the first order calculations(i.e., reattachment length, mean velocity, pressure), however, slight deviations in the second order(i.e., kinetic energy and turbulence intensity). Comparing with the previous results using the k-$\varepsilon$ model, the ARS model predicts better than the standard k-$\varepsilon$ model, however, slightly worse than the k-$\varepsilon$ model including the streamline curvature modification. Additionallay this study can reconfirm that the skew-upwind scheme has approximately 25% improved predictability than the upwind scheme.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
• /
• pp.466-470
• /
• 1988

A tunable reduced-order distillation model is proposed for real-time applications. To develop the model, a binary distillation column with MaCabe-Thiele assumptions was considered first and then the governing equations for the column were reduced to a simplified vector differential equations using the collocation method combined with cubic spline interpolation function. The final reduced-order model has four tuning parameters, relative volatilities and liquid holdups for rectifying and stripping sections, respectively. To assess the applicability of the developed model,the real-time adjustment of the model was tried by recursively updating the tuning parameters using the BKF algorithm. As a result, it was found that the reduced-model follows the simulated distillation process very closely as the parameters are improved.

• Carbon letters
• /
• 제7권3호
• /
• pp.171-179
• /
• 2006

A carbonaceous sorbent was prepared from rice husk via sulphuric acid treatment. After preparation and washing, the wet carbon with moisture content 85% was used in its wet status in this study due to its higher reactivity towards Cr(VI) than the dry carbon. The interaction of Cr(VI) and the carbon was studied and two processes were investigated in terms of kinetics and equilibrium namely Cr(VI) removal and chromium sorption. Cr(VI) removal and chromium sorption were studied at various initial pH (1.6-7), for initial Cr(VI) concentration (100 mg/l). At equilibrium, maximum Cr(VI) removal occurred at low initial pH (1.6-2) where, Cr(III) was the only available chromium species in solution. Cr(VI) removal, at such low pH, was related to the reduction to Cr(III). Maximum chromium sorption (60.5 mg/g) occurred at initial pH 2.8 and a rise in the final pH was recorded for all initial pH studied. For the kinetic experiments, approximate equilibrium was reached in 60-100 hr. Cr(VI) removal data, at initial pH 1.6-2.4, fit well pseudo first order model but did not fit pseudo second order model. At initial pH 2.6-7, Cr(VI) removal data did not fit, anymore, pseudo first order model, but fit well pseudo second order model instead. The change in the order of Cr(VI) removal process takes place in the pH range 2.4-2.6 under the experimental conditions. Other two models were tested for the kinetics of chromium sorption with the data fitting well pseudo second order model in the whole range of pH. An increase in cation exchange capacity, sorbent acidity and base neutralization capacity was recorded for the carbon sorbent after the interaction with acidified Cr(VI) indicating the oxidation processes on the carbon surface accompanying Cr(VI) reduction.

• 한국기계가공학회지
• /
• 제21권4호
• /
• pp.53-59
• /
• 2022

In this study, an enhanced first-order shear deformation theory is proposed to efficiently and accurately predict the thermo-mechanical-viscoelastic coupled behavior of laminated composite structures. To this end, transverse shearstress and displacement fields are independently assumed, and the strain-energy relationship between these fields issystematically established using the mixed variational theorem (MVT). In MVT, the transverse shear stress fields are obtained from the third-order zigzag model, whereas the displacement fields of the conventional first-order model are considered to amplify the benefits of numerical efficiency. Additionally, a transverse displacement field with a smooth parabolic distribution is introduced to accurately predict the thermal behavior of composite structures. Furthermore, the concept of Laplace transformation is newly employed to simplify the viscoelastic problem, similar to the linear-elastic problem. To demonstrate the performance of the proposed theory, the numerical results obtained herein were compared with those available in the literature.

• 공업화학
• /
• 제34권2호
• /
• pp.153-160
• /
• 2023

본 논문에서는 미이용 바이오매스로부터 바이오차를 생산하고 메틸렌블루 흡착 특성을 평가하였다. 바이오매스는 주로 셀룰로오스, 헤미셀룰로오스, 리그닌으로 구성되어 있으며 회분의 함량은 벌채부산물에서 가장 높았다. 탄화 온도가 증가할수록 탄화 수율은 감소하였으며, 수소와 산소 함량도 감소하였다. 반면, 탄소 함량은 증가하였다. 탄화 온도가 증가할수록 바이오차의 비표면적과 미세기공은 증가하였다. 바이오차 비표면적은 탄화 온도 600 ℃에서 가장 높았다(216.15~301.80 m² /g). 600 ℃에서 탄화한 바이오차를 이용하여 메틸렌블루 흡착 실험을 수행한 결과, 참나무, 벌채부산물, 사과 전정가지의 흡착 거동은 Freundlich model, 복숭아 전정가지는 Langmuir model에 적합하였다. 흡착 동역학에서 참나무와 복숭아 전정가지는 pseudo-first-order model, 벌채부산물과 사과 전정가지는 pseudo-second-order model에 적합하였다.

• 한국환경과학회지
• /
• 제2권4호
• /
• pp.271-278
• /
• 1993

Nonylphenol ethoxylates-30을 분해할 수 있는 Pseudomonas sp.를 분리, 동정하였다. Nonylphenol ethoxylates-30 의 최적분해조건은 탄소원으로 nonylphenol ethoxylates-30 1.0 g/ι, 질소원으로 ammonium nitrate 0.02 g/ι, pH 7.5, 30였다. 최적분해 조건에서 nonylphenol ethoxylates-30은 배양 30시간 후 89%가 분해되었다. 최적분해조건에서 nonylphenol ethoxylates-30의 초기농도가 각각 100 ppm, 500 ppm, 1000 ppm, 5000 ppm일 때 시간에 따른 분해율을 수식으로 설명할 수 있는 가장 적합한 분해 kinetics는 각각 first order model, Monod no growth model, Monod with growth model로 나타났다.