• 한국환경과학회지
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• 제23권1호
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• pp.153-156
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• 2014

This study was conducted to evaluate the effects of sea urchin shell powder on nitrogen characteristics in poultry litter by assigning ninety 1-d-old male broiler chicks (Arbor Acres) to one of 3 treatments (control, 1% sea urchin shell powder, and 1% feed additives) in 3 replicates of 10 birds each. For all treatments, the overall dry matter contents were decreased (P < 0.05) as time increased, except for at 1 week. When compared with controls, the dietary sea urchin shell powder and feed additives for 0 and 3 weeks did influence their TN contents, but not for 1, 2 and 4 weeks. The treatments with sea urchin shell powder and feed additives had a significant (P < 0.05) influence on $NH_3$-N in poultry litter compared with controls. However, at 4 weeks, no marked differences were observed in $NH_3$-N contents among treatments. Treatments with 1% sea urchin shell powder might enhance the value of poultry litter as N fertilizer.

• 한국정밀공학회지
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• 제23권8호
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• pp.203-210
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• 2006

This paper focuses on the development of RT technology suitable for manufacturing a small quantity of metal prototype of a precise part from an RP master. Dimensional accuracy and surface roughness are evaluated from Thermojet part of a 3D printer, and effective post-processing method is introduced. Investment casting is done using a prototype built from 3D printer as a wax pattern. Ceramic shell investment casting technique is developed to build a prototype with materials mostly wanted. Also, experimental result shows this research is very useful in manufacturing of a small quantity of functional part or a test part of a specific material.

• 한국전산유체공학회지
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• 제12권3호
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• pp.13-19
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• 2007

A numerical simulation on the heat transfer and flow field was carried out to improve the performance of the shell and tube heat exchanger. The steady incompressible 3-D Navier-Stokes solution is obtained with the actual operational condition and geometry of the heat exchanger. Based on this study, it is noted that the present geometry of the heat exchanger causes poor heat transfer since the air inside shell does not flow through the tube bundle, but around it. The enhancement of the heat transfer can be achieved by the variation of the design factor like the sealing strip located on the top/bottom and middle of the baffle, but it causes the increasement of the pressure drop. In this paper, the effects of the location and size of the sealing strips and flow rate through the heat exchanger on the heat transfer and pressure drop are studied.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.648-656
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• 2004

In this study, a highly efficient shell-and-tube heat exchanger with plate fins is considered to improve thermal performance of the conventional shell-and-tube heat exchanger. This type of shell-and-tube heat exchanger with plate fins of various shape is simulated three-dimensionally using a commercial thermal-fluid analysis code. CFX4.4. The effect of the shape of the plate fin on heat transfer characteristics is also investigated by the simulation. Plate fins of four different shapes. plane, plane-slit. wave. and wave-slit fins, are considered. The flow fields, pressure drop and heat transfer characteristics in the heat exchanger are calculated. It is proved that the shell-and-tube heat exchanger with plate fins is superior to the conventional shell-and-tube heat exchanger without plate fins in terms of heat transfer. The shape of the plate fin is important in the performance of a heat exchanger such as heat transfer and pressure drop.

• 설비공학논문집
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• 제17권12호
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• pp.1161-1168
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• 2005

A Multi-Sectional 3D-PTV algorithm was developed to reduce the calculation time of the conventional GA-3D-PTV. The hardware system of the constructed 3D-PTV system consists of two high-speed cameras ($1,024\times1,018$ pixels, 60 fps), a metal halogen lamp (400W) and a host computer. The sphere(D=30mm) is suspended in a circulating water channel $(300mm\times300mm\times1,200m)$ and Reynolds number is 1,130. About 5,000 instantaneous three-dimensional velocity vectors have been obtained by the constructed 3D-PTV system. Turbulent properties such as turbulent intensity, Reynolds stress and turbulent kinetic energy were obtained. An eigenvalue analysis was carried out using the obtained instantaneous 3D velocity vectors to get the topological relations of the asymptotically stable critical point. Two structured shells, inner shell and outer shell, were found in the sphere wake and their motions were clarified by the measured data.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.447-457
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• 2009

A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

• 한국양식학회지
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• 제13권2호
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• pp.119-128
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• 2000

진주담치(Mytilus edulis), 홍합(Mytilus coruscus), 참굴(Crassostrea gigas) 및 진주조개(Pinctata fucata martensii)를 인위적인 방란 방정을 유도하여 이들의 수정란과 부유유생을 사육하여 난 발생, 유생의 성장 및 형태를 비교한 결과는 다음과 같다. 수정란의 크기는 진주담치와 홍합이 각각 65.1 ${\mu}m$, 70.3 ${\mu}m$로 비슷한 크기를 보였고, 참굴과 진주조개는 각각 52.3 ${\mu}m$, 45.3 ${\mu}m$로 비슷한 크기를 보였다. 수정란에서 D형 유생으로 되는 데 소요되는 시간은 진주담치와 참담치는 자연수온(17.0$\pm$1$^{\circ}C$)에서 각각 47시간55분, 45시간 55분이 소요되었고, 참굴과 진주조개는 수온 21.$0^{\circ}C$와 26.$0^{\circ}C$에서 각각 23시간 55분과 22시간이 소요되었다. 진주담치, 홍합, 참굴, 진주조개가 초기 D형 유생에서 부착기 유생으로 성장하는 데는 각각의 수온에서 각각 20일, 27일, 22일, 및 21일이 소요되었고 이때의 평균 각장의 크기는 각각 194.1 ${\mu}m$, 233.6 ${\mu}m$, 274.9 ${\mu}m$, 190.9 ${\mu}m$ 였다. 초기 D형 유생에서 초기 부착기 유생까지 각장(L)과 각고(H)의 상관관계는 높으며, 각장에 따른 각고/각장의 비율(H/L)은 진주담치: H/L : 0.002L+0.5334 (($R^2$ = 0.957), 홍합: H/L : 0.001L+0.603 ($R^2$ : 0.944), 참굴: H/L =0.001L+0.871 (($R^2$=0.550) 및 진주조개: H/L =0.001L+0.791 (($R^2$ = 0.700)로 나타났다

• Asian-Australasian Journal of Animal Sciences
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• 제20권6호
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• pp.933-938
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• 2007

An experiment was conducted to study the laying performance, shell quality, bone mineralization, hatchability of eggs and performance of progeny (weight at day one and 14 d of age, P content in day old chick, leg score and survivability of chicks) of synthetic broiler breeders fed different levels of non-phytate phosphorus (NPP). Six levels of NPP (1.2, 1.8, 2.4, 3.0, 3.6 and 4.2 g/kg diet) at a constant calcium (Ca) level (30 g/kg) in a maize-soya-deoiled rice bran based diet were tested. Levels of dicalcium phosphate, shell grit and deoiled rice bran were adjusted to achieve the desired levels of NPP and Ca. Each level of NPP was fed with a weighed quantity of feed (160 g/b/d) to 40 female broiler breeders from 25 to 40 weeks of age housed in individual cages. Each bird was considered as a replicate. Egg production, feed/egg mass, body weight, egg weight, shell weight, shell thickness, egg specific gravity, serum Ca content and tibia breaking strength were not influenced (p>0.05) by the variation in dietary NPP levels tested. Increasing the dietary levels of NPP did not influence the hatchability of eggs, phosphorus (P) contents both in egg yolk and day old chick, chick body weight at day one and 14 d of age, leg score and survivability of chicks up to 14 d of age. Maximum response ($p{\leq}0.01$) in shell breaking strength, tibia ash and serum inorganic P contents were observed at NPP levels of 2.09, 2.25 and 3.50 g per kg diet, respectively. The retention of Ca increased, while the P retention decreased ($p{\leq}0.01$) with increasing dietary levels of NPP. Though maximum responses in shell breaking strength, bone ash and serum inorganic P were observed at NPP higher than 1.2 g/kg diet, the broiler breeder performance in terms of egg production, shell quality, hatchability of eggs and progeny performance and their survivability was not influenced by dietary NPP concentrations. It is concluded that synthetic broiler breeders maintained in cages do not require more than 1.2 g NPP/kg diet with a daily intake of 192 mg NPP/b/d during 24 to 40 weeks of age.

• International Journal of Industrial Entomology and Biomaterials
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• 제8권1호
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• pp.113-115
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• 2004

Six generations (P$_1$, P$_2$, F$_1$, BC$_1$, BC$_2$ and F$_2$) of four bivoltine silkworm crosses (SKAU-R-1 ${\times}$ Yakwei, SKAU-R-6 ${\times}$ Yakwei, CSR$_2$ ${\times}$ CSR$_4$ and SH$_{6}$${\times}$ NB$_4$D$_2$) were evaluated in a completely randomized block design with 5 replications for each treatment. The generation mean 2 in respect of 3 metric traits (single cocoon weight, single shell weight, and shell ratio ％), were subjected to Cavallis joint scaling test. Additive dominance model was found to be adequate in CSR$_2$${\times}$CSR$_4$ and SH$_{6}$${\times}$ NB$_4$D$_2$ for single cocoon weight and shell weight and SKAU-R-6 ${\times}$ Yakwei for shell ratio(％). Whereas, in rest of the crosses epistasis was evident in the traits under investigation. Magnitude of additive gene effect (d) was greater than dominance(h) in SH$_{6}$${\times}$NB$_4$D$_2$ and SKUA-R-6${\times}$Yakwei for shell ratio (％) and in CSR$_2$${\times}$ CSR$_4$ for shell weight. Thus selection for these traits in early segregating generations of these crosses would be effective for obtaining considerable genetic gain. gain.

• 한국공간구조학회논문집
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• 제4권4호
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• pp.113-128
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• 2004

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies and mode shapes of solid paraboloidal and complete (that is, without a top opening) paraboloidal shells of revolution with variable wall thickness. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. The ends of the shell may be free or may be subjected to any degree of constraint. Displacement components $u_r,\;u_{\theta},\;and\;u_z$ in the radial, circumferential, and axial directions, respectively, are taken to be sinusoidal in time, periodic in ${\theta}$, and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the paraboloidal shells of revolution are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the complete, shallow and deep paraboloidal shells of revolution with variable thickness. Numerical results are presented for a variety of paraboloidal shells having uniform or variable thickness, and being either shallow or deep. Frequencies for five solid paraboloids of different depth are also given. Comparisons are made between the frequencies from the present 3-D Ritz method and a 2-D thin shell theory.