• Journal of Veterinary Science
• /
• 제25권4호
• /
• pp.58.1-58.8
• /
• 2024

Importance: Over the past decade, catfish farming has increased in Southeast Asia. However, there has been no existing for pharmacokinetic data in the hybrid catfish (Clarias macrocephalus x C. gariepinus). Objective: This study was designed to evaluate the pharmacokinetic characteristics of oxytetracycline (OTC) in the hybrid catfish, following single intravascular (IV) or oral (PO) administration at a single dosage of 50 mg/kg body weight (BW). Methods: In total, 140 catfish (each about 100-120 g BW) were divided into two groups (n = 70). Blood samples (0.6-0.8 mL) were collected from ventral caudal vein at pre-assigned times up to 144 h (sparse samples design). OTC plasma concentrations were analyzed using high-performance liquid chromatography-photodiode array detector. Results: The pharmacokinetic parameter of OTC was evaluated using a non-compartment model. OTC plasma concentrations were detectable for up to 144 and 120 h after IV and PO, respectively. The elimination half-life value of OTC was long with slow clearance after IV administration in hybrid catfish. The average maximum concentration value of OTC was 2.72 ㎍/mL with a time at the maximum concentration of 8 h. The absolute PO bioavailability was low (2.47%). Conclusions and Relevance: These results showed that PO administration of OTC at a dosage of 50 mg/kg BW was unlikely to be effective for clinical use in catfish. The pharmacodynamic properties and clinical efficacy of OTC after multiple medicated feed are warranted.

• 한국가구학회지
• /
• 제24권4호
• /
• pp.318-328
• /
• 2013

This study aimed to examine the theoretical consideration and concept of hybrid that could be applicable to wood product design, to analyze design trend according to the morphological transformation by means of combination of hybrid material and function, to understand the correlation between type of wood product and materials and to apply it to the domestic and overseas hybrid concept of wood product design study. A study of assembling output by empirical experiment to embed natural resources into acrylic resin in order to develop wood products was carried out. And an wood product was suggested that satisfied lighting and hanger function through a new wood product design development combined with hanger function and lighting function. Through such process, a new design paradigm was suggested to cope with the periodic trend and to induce mass production of designed product. Thus, this study set a new guideline for activating wood product design and attempted to meet the social demand of encouraging new value creation.

• Steel and Composite Structures
• /
• 제30권1호
• /
• pp.31-46
• /
• 2019

In the present study, the various dynamic properties of MWCNT embedded fiber reinforced polymer uniform and tapered composite (MWCNT-FRP) plates are investigated. Various configurations of a tapered composite plate with ply-drop off and uniform composite plate have been considered for the development of the finite element formulation and experimental investigations. First order shear deformation theory (FSDT) has been used to derive the kinetic and potential energy equations of the hybrid composite plates by including the effect of rotary inertia, shear deformation and non-uniformity in thickness of the plate. The governing equations of motion of FRP composite plates without and with MWCNT reinforcement are derived by considering a nine- node rectangular element with five degrees of freedom (DOF) at each node. The effectiveness of the developed finite element formulation has been demonstrated by comparing the natural frequencies and damping ratio of FRP composite plates without and with MWCNT reinforcement obtained experimentally. Various parametric studies are also performed to study the effect of CNT volume fraction and CNT aspect ratio of the composite plate on the natural frequencies of different configurations of CNT reinforced hybrid composite plates. Further the forced vibration analysis is performed to compare the dynamic response of the various configurations of MWCNT-GFRP composite plate with GFRP composite plate under harmonic excitations. It was observed that the fundamental natural frequency and damping ratio of the GFRP composite plate increase approximately 8% and 37% respectively with 0.5wt% reinforcement of MWCNT under CFCF boundary condition. The natural frequencies of MWCNT-GFRP hybrid composite plates tend to decrease with the increase of MWCNT volume fraction beyond 2% due to agglomeration of CNT's. It is also observed that the aspect ratio of the CNT has negligible effect on the improvement of dynamics properties due to randomly orientation of CNT's.

• Smart Structures and Systems
• /
• 제14권3호
• /
• pp.397-418
• /
• 2014

In this paper, a simple two-step method for structural vibration-based health monitoring for beam-like structures have been extended to plate-like structures with though-thickness cracks. Crack locations and severities of plate-like structures are detected using a hybrid approach. The interval wavelet transform is employed to extract crack singularity locations from mode shape and support vector regression (SVR) is applied to predict crack serviettes form crack severity detection database (the relationship of natural frequencies and crack serviettes) using several natural frequencies as inputs. Of particular interest is the natural frequencies estimation for cracked plate-like structures using Rayleigh quotient. Only the natural frequencies and mode shapes of intact structures are needed to calculate the natural frequencies of cracked plate-like structures using a simple formula. The crack severity detection database can be easily obtained with this formula. The hybrid method is investigated using numerical simulation and its validity of the usage of interval wavelet transform and SVR are addressed.

• 한국가스학회지
• /
• 제18권4호
• /
• pp.13-20
• /
• 2014

상업용 천연가스 배급 시스템에서 천연가스의 공급압력은 압력조절밸브를 사용하여 제어하며 이때 막대한 압력에너지가 낭비된다. 이러한 폐압에너지는 터보 팽창기와 같은 터보기계를 사용하여 회수할 수 있으나 팽창과정에서 발생하는 Joule-Thompson 효과에 따라서 큰 온도강하가 발생한다. 터보 팽창기 전단 또는 후단에 보일러를 설치하여 영하의 온도를 방지할 수 있으며 또한 보일러를 대체하여 연료전지나 가스엔진의 폐열을 이용하여 천연가스를 예열할 수도 있으나 하이브리드 시스템의 구동을 위해 운영규모에 따라 일정량을 소모해야 한다. 이 연구에서는 천연가스가 가지고 있는 압력에너지를 활용하여 천연가스의 소모 없이 터보 팽창기와 연결된 히트펌프를 구동하여 천연가스를 예열하는 시스템을 제안하고 증발온도, 응축온도 및 작동유체의 변화에 따른 시스템의 열역학적 특성을 분석하였다. R717 냉매가 예상 작동범위 내에서 가장 높은 COP와 가장 낮은 압축일을 나타내 제안된 하이브리드 시스템에 적합함을 확인하였다. 보일러시스템과의 경제성 분석을 통해 천연가스를 LNG 형태로 수입하고 있는 국내의 경우 히트펌프 하이브리드 시스템이 경쟁력 있음을 확인하였다.

• Korean Membrane Journal
• /
• 제11권1호
• /
• pp.21-28
• /
• 2009

We investigated the effect of organic materials on membrane fouling in advanced drinking water treatment by a hybrid module packed with granular activated carbon (GAC) outside multi-channel ceramic microfiltration membrane. Synthetic water was prepared with humic acid and kaolin to simulate natural water resouces consisting of natural organic matter and inorganic particles. Kaolin concentration was fixed at 30 mg/L and humic acid was changed as 2~10 mg/L to inspect the effect of organic matters. Periodic back-flushing using permeate water was performed for 10 sec per filtration of 10 min. As a result, both resistance of membrane fouling (Rf) and permeate flux (J) were influenced highly by concentration of humic acid. It proved that NOM like humic acid could be an important factor on membrane fouling in drinking water treatment. Turbidity and UV254 absorbance were removed up to above 97.4% and 59.2% respectively.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제5권4호
• /
• pp.529-545
• /
• 2013

Strong restrictions on emissions from marine power plants (particularly $SO_x$, $NO_x$) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heat-recovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

• 한국전산유체공학회지
• /
• 제16권4호
• /
• pp.39-46
• /
• 2011

A numerical study of a turbulent natural convection in an enclosure with the lattice Boltzmann method (LBM) is presented. The primary emphasis of the present study is placed on investigation of accuracy and numerical stability of the LBM for the turbulent natural convection flow. A HYBRID method in which the thermal equation is solved by the conventional Reynolds averaged Navier-Stokes equation method while the conservation of mass and momentum equations are resolved by the LBM is employed in the present study. The elliptic-relaxation model is employed for the turbulence model and the turbulent heat fluxes are treated by the algebraic flux model. All the governing equations are discretized on a cell-centered, non-uniform grid using the finite-volume method. The convection terms are treated by a second-order central-difference scheme with the deferred correction way to ensure accuracy and stability of solutions. The present LBM is applied to the prediction of a turbulent natural convection in a rectangular cavity and the computed results are compared with the experimental data commonly used for the validation of turbulence models and those by the conventional finite-volume method. It is shown that the LBM with the present HYBRID thermal model predicts the mean velocity components and turbulent quantities which are as good as those by the conventional finite-volume method. It is also found that the accuracy and stability of the solution is significantly affected by the treatment of the convection term, especially near the wall.

• 한국어류학회지
• /
• 제31권4호
• /
• pp.235-240
• /
• 2019

자바리와 대왕자바리 2종을 대상으로 MS-222 농도 및 수온에 따른 마취효과 실험을 수행하였다. 농도는 100, 150, 200 그리고 250 ppm을, 수온은 18, 22, 26 그리고 30℃에서 마취 및 회복시간을 조사하였다. MS-222 농도와 수온이 높아질수록 마취시간이 짧아지는 경향을 보였으며, 회복시간은 농도와는 비례하지만 수온과는 반비례하는 경향을 보였다. 회복시간은 22℃ 이하에서는 큰 차이가 없었다. 자바리의 최적 마취조건은 회복시간이 가장 짧은 30℃와 100 ppm, 대왕자바리의 경우 30℃ 150 ppm이 회복시간이 100 ppm과 유의적으로 차이가 없으면서 마취시간은 유의하게 짧아 가장 적합했다. 이원배치분산분석 결과 자바리와 대왕자바리의 종 간 유의한 차이가 있었으나, 종과 농도 그리고 종, 농도, 수온에 대한 상호작용 효과는 없었다.

• 태양에너지
• /
• 제11권1호
• /
• pp.27-40
• /
• 1991

에너지 소비 구조의 개선을 목적으로 한 자연에너지 이용시스템의 도입이 전력 계통의 계획 운용에 미치는 영향을 다목적 최적화 방법을 이용하여 평가하는 방법이 논하여 지고 있다. 본 연구에서는 시험 제작한 태양열과 풍력 에너지를 주체로하는 자연에너지 복합 이용시스템이 특정 지역에 복수 도입되어 지는 경우 전력 통계 운용에 의한 경제성, 안정성, 환경에 대한 영향 평가 방법을 검토하였다. 연구 방법은 대상 지역의 일사 분포와 풍속 분포에 의해서 취득 가능한 에너지를 산정하여 전력 계통 부하의 형상에 미치는 영향을 구하였고, 다음에는 대상 기간에 의한 최적 발전 배분을 결정하여 경제성, 안정성, 환경 지표 등의 평가를 하였다. 지금까지는 자연에너지 이용시스템의 도입에 대하여 경제적 측면만 논의되었지만, 본 연구에서 제한된 방법에 의해 안정성과 환경 보전의 영향을 고려한 평가 방법도 가능하다는 것을 나타내었다.