• Wind and Structures
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• 제4권6호
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• pp.481-494
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• 2001

Wind tunnel pressure tests were conducted on a 1:100 scale model of a large industrial building with solar panels mounted parallel to the flat roof. The model form was chosen to have the same aspect ratio as the Texas Tech University test building. Pressures were simultaneously measured on the roof, and on the topside and underside of the solar panel, the latter two combining to produce a nett panel pressure. For the configurations tested, varying both the lateral spacing between the panels and the height of the panels above the roof surface had little influence on the measured pressures, except at the leading edge. The orientation of the panels with respect to the wind flow and the proximity of the panels to the leading edge had a greater effect on the measured pressure distributions. The pressure coefficients are compared against the results for the roof with no panels attached. The model results with no panels attached agreed well with full-scale results from the Texas Tech test building.

• Journal of the Optical Society of Korea
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• 제17권1호
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• pp.97-102
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• 2013

Frequency tuning characteristics of a THz-wave by varying phase-matching angle and pump wavelength in a noncollinear phase-matching THz-wave parametric oscillator (TPO) are analyzed. A novel scheme to realize the tuning of a THz-wave by moving the cavity mirror forwards and backwards is proposed in a noncollinear phase-matching TPO. The parametric gain coefficients of the THz-wave in a $LiNbO_3$ crystal are explored under different working temperatures. The relationship between the poling period of periodically poled $LiNbO_3$ (PPLN) and the THz-wave frequency under the condition of a quasi-phase-matching configuration is deduced. Such analyses have an impact on the experiments of the TPO.

• Structural Monitoring and Maintenance
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• 제6권3호
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• pp.191-218
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• 2019

The aim of the present investigation is to examine the propagation of plane waves in transversely isotropic homogeneous magneto thermoelastic rotating medium with fractional order heat transfer. It is found that, for two dimensional assumed model, there exist three types of coupled longitudinal waves (quasi-longitudinal, quasi-transverse and quasi-thermal waves). The wave characteristics such as phase velocity, attenuation coefficients, specific loss, penetration depths, energy ratios and amplitude ratios of various reflected and transmitted waves are computed and depicted graphically. The conservation of energy at the free surface is verified. The effects of rotation and fractional order parameter by varying different values are represented graphically.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.894-900
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• 2021

This paper examines sorption of Pd(II) onto illite, MX-80 bentonite, and Queenston shale in Na-Ca-Cl solutions of varying ionic strength (IS) from 0.01 to 6.0 mol/L (M) and pH_c ranging from 3 to 9 under atmospheric conditions. A 2-site protolysis non-electrostatic surface complexation and cation exchange model was applied to the Pd sorption onto illite and MX-80 using PHREEQC, and the model results were compared to the experimental ones obtained in this work. Surface complexation and cation exchange constants were estimated for both illite and MX-80 through the optimization process to bring the predicted distribution coefficients from the model into alignment with the experimentally derived values. These optimized surface complexation constants were compared to existing linear free energy relationships (LFER).

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.957-966
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• 2020

This paper presents the virtual mass method to implement the prediction of total resistance for ice-going ship in floe ice region based on the combined method of CFD and DEM. Two ways of floe ice distribution are adopted for the analysis and comparison. The synthetic ice model test has been conducted to determine the optimal virtual mass coefficients for the two different floe ice distributions. Moreover, the further verification and prediction are developed in different ice conditions. The results show that, the fixed and random distributions in numerical method can simulate the interaction of ship and ice vividly, the trend of total resistance varying with the speed and ice concentration obtained by the numerical simulation is consistent with the model test. The random distribution of floe ice has higher similarity and better accuracy than fixed distribution.

• Advances in materials Research
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• 제9권4호
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• pp.289-309
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• 2020

The aim of the present investigation is to examine the propagation of plane harmonic waves in transversely isotropic homogeneous magneto visco thermoelastic rotating medium with fractional order heat transfer and two temperature. It is found that, for two dimensional assumed model, there exist three types of coupled longitudinal waves (quasi-longitudinal, quasi-transverse and quasi-thermal) in frequency domain. phase velocities, specific loss, penetration depth, attenuation coefficients of various reflected waves are computed and depicted graphically. The effects of viscosity and fractional order parameter by varying different values are represented graphically.

• Asian-Australasian Journal of Animal Sciences
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• 제14권7호
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• pp.970-973
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• 2001

An experiment was carried out to assess the effect of feeding concentrate mixtures varying in bypass protein levels with urea-treated or untreated grass on the performance of twelve Red Kandhari calves (14 months of age and 78.15 kg body weight) for a period of 75 days. Dry grass was treated with 4 percent urea solution and ensiled for 30 days. The CP ($N{\times}6.25$) content in urea treated grass increased from 3.96 to 8.89 percent. Two iso-caloric and iso-nitrogenous concentrate mixtures (CM-I and CM-II) varying in RDP to UDP ratio viz., 65:35 and 55.45 were prepared. The calves in control group ($T_1$) were fed concentrate mixture-I with ad libitum untreated dry grass and those in experimental group ($T_2$) were fed concentrate mixture-II with ad libitum urea treated dry grass. The dry matter consumption in group $T_2$ was significantly (p<0.01) higher as compared to group $T_1$. The total DMI in $T_1$ and $T_2$ was 146.92 and 166.95 kg respectively, whereas the DMI per day and per 100 kg body weight was 1.94 and 2.22 and 1.90 and 2.35 kg, respectively. The average total gain in body weight (kg) and average daily gain (g) of calves in $T_2$ was significantly (p<0.01) higher as compared to those in $T_1$ the values being 28.66, 18.33 and 382.16, 244.44, respectively. Feed efficiency in terms of kg DM per kg gain in body weight was significantly (p<0.01) lower in group $T_1$ than in $T_2$. The cost of feed per kg gain in body weight for $T_2$ and $T_1$ group was Rs. 21.14, 28.22, respectively. The digestibility coefficients of DM, CP, EE, CF, NFE, NDF and ADF were 59.60, 57.50, 53.00, 65.04, 45.82, 48.48, 52.48 and 55.73 for $T_1$ group. The coressponding values were 68.78, 67.80, 59.83, 71.41, 49.93, 53.37 and 57.81, respectively for $T_2$ group. The digestibility coefficients for all the proximate principles in $T_2$ were significantly (p<0.01) higher as compared to $T_1$. However, NDF and ADF digestibilities were not significantly different. Nutritive value determined in terms of DCP and TDN for The experimental ration was significantly (p<0.01) higher than control ration, the values being 7.32 and 47.34 and 9.39 and 52.40% respectively. The blood urea nitrogen levels at 0, 3 and 6 h interval after feeding were significantly (p<0.01) lower in calves fed experiment ration as compared to control. The overall results indicated that in Red Kandhari calves an optimum growth can be economically achieved by feeding 4 percent urea treated dry and mature grass as basal roughage supplemented with a concentrate mixture containing 20 percent CP, 70% TDN and 45% UDP/bypass protein.

• 한국수산과학회지
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• 제27권6호
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• pp.771-781
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• 1994

광전도측정기(Beam Transmissometer)를 이용한 간접적인 부유물질농도결정의 신뢰도와 문제점을 조사하기 위하여, Neuse 강 (미국 North Carolina주) 하구의 15개 정점에서 13개월에 걸쳐 매월 광전도도와 부유물질의 농도를 측정, 상관관계를 분석하였다. 부유물질농도(SPM)와 광감쇄계수(Beam Attenuation Coefficient, c) 간의 상관계수(Coefficient of Determination, $r^2$) 및 상관함수의 기울기(a)는 월별($r^2:\;0.12{\sim}0.93,\;a:\;0.53{\sim}5.63$) 및 정점별($r^2:\;0.21{\sim}0.96,\;a:\;1.04{\sim}4.94$)로 극심한 변동폭을 보였으나, 표층이 저층보다 밀접한 상관관계를 보였으며, 해수의 영향이 연중 거의 미치지 않는 최상류지점에서 가장 높은 상관계수($r^2=0.96$)를 나타내었다. 계절별로 다양한 변화를 보이는 부유물질의 유기물함량은 SPM과 c 간의 함수관계에 중요한 영향을 미치지 않으나, 시간적, 공간적으로 다양하게 변화하는 부유물질응집체(aggregate)에 의해 부유입자의 광학적 특성 (입도, 모양 및 광굴절지수 등)이 변화하게되며, 따라서 SPM과 c의 관계를 복잡하게 하는 것으로 생각된다. 광전도측정기의 효과적인 이용을 위해서는 정확한 보정이 필요하나, 부유입자의 광학적 특성이 다양하게 변화하는 강하구와 같은 환경에서는 시간적, 공간적으로 빈번한 보정으로도 신뢰도 높은 상관관계의 획득이 불가능하다. 그러나 광전도측정기의 최선의 용도는 수괴의 탁도의 급격한 변동을 감지하는데 있으며, 부유입자의 광학적 특성이 비교적 균일한 외해에서나 혹은 오차범위를 허용할 수 있는 상황에서는 매우 유용하게 사용될 수 있다.

• 한국해안·해양공학회논문집
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• 제32권2호
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• pp.106-121
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• 2020

항 외곽시설 신뢰성 설계가 합리적으로 구현하기 위해서는 우리나라 해양환경 특성이 반영된 확률모형이 필요하며 이러한 시각에서 본 연구에서는 천 해역 확률모형 개발을 위한 기초연구의 일부로 불규칙 파랑 천수 과정을 수치 모의하였다. 수치 모의는 자연해안에서 흔히 관측되는 사주가 원빈에 형성된 해안을 대상으로 수행하였으며 파랑모형은 spatially filtered Navier-Stokes Eq., LES[Large Eddy Simulation], one equation dynamic Smagorinsky turbulence closure 등으로 구성하였다. 불규칙 파랑은 우리나라 동해안에서 관측되는 너울 특성을 반영하기 위해 다양한 첨두 증강계수를 지니는 JONSWAP 스펙트럼과 random phase method를 사용하여 모의하였다. 파고분포의 모수는 먼저 수치 모의에서 관측된 자유수면 시계열 자료를 threshold crossing method로 파별 해석[wave by wave analysis]하여 개별 파랑을 특정하고, 이어 이렇게 특정된 파마루와 파곡 빈도 해석결과로부터 산출하였다. 모의결과 현재 천 해역 파고분포를 대표하는 수정 Glukhovskiy 파고분포는 큰 파고와 작은 파고 발생확률은 과다하게, 중간 크기 파고 발생확률은 과소하게 평가하는 것으로 모의 되었으며, 이에 반해 본 논문에서 제시된 파고분포의 경우 일치도가 상당하였다. 또한, 전술한 수정 Glukhovskiy 파고분포와의 간극은 쇄파역에서 제일 현저하게 관측되어 수정 Glukhovskiy 파고분포를 쇄파역 언저리에 거치되는 외곽시설 신뢰성 설계에 적용하는 일은 지양되어야 할 것으로 판단된다.

• Ecology and Resilient Infrastructure
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• 제10권3호
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• pp.51-63
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• 2023

하천내 수목관리는 홍수와 생태 관리의 균형점을 찾는다는 점에서 매우 중요하며 이를 위해서는 수목이 하천 수위에 미치는 영향을 정확하게 평가할 필요가 있다. 본 연구에서 수목에 작용하는 항력을 고려하는 수목조도공식 8개에 대해 검토하여 실무 수리계산의 관점에서 수목 조도계수 공식의 특성과 적용성을 평가하였다. 개별 수목 조도계수 공식의 수심별 조도계수 산정 특성을 비교하고, 수관부 영향, 수목밀도와 직경 영향, 수목 강성계수 영향, 수위 산정 결과 등을 분석하였다. 동일 조건 수심별 조도계수 비교를 통해 Kouwen and Fathi-Moghadam 공식과 Fischenich 공식은 타 공식에 비해 과도한 조도계수를 산정하였다. 수관부, 수목 직경, 수목 밀도 등은 공식에 따라 상이한 경향을 나타내나 과도한 특이점은 없는 것으로 나타났다. 수목 강성계수를 고려하는 Freeman et al. 공식과 Whittaker et al. 공식은 강성계수에 따라 조도계수가 매우 큰 차이를 나타낸다. 8개 공식의 조도계수 산정 결과를 이용하여 국내 중소규모 가상 하천에 적용한 결과 최대 약 0.2 - 0.4 m 정도의 수위 상승효과를 나타내고 있다. 이상의 검토를 통해 유사한 특성을 가지며 입력자료의 불확실성이 낮은 Baptist et al., Huthoff et al., Cheng, Luhar and Nepf 등의 4개 공식이 실무 적용에 적합한 것으로 판단하였다.