• 한국발생생물학회지:발생과생식
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• 제19권4호
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• pp.197-207
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• 2015

This study investigated structure and function of the reproductive system in Aplysia kurodai by means of anatomical, histological, and histochemical observation. Reproductive system of this species is consisted of ovotestis, small hermaphroditic duct, ampulla, accessory genital mass and large hermaphroditic duct. The ovotestis is composed of a large number of follicles, and both oocytes and spermatocytes matured in the same follicle. The small hermaphroditic duct is a single tube and contains a swelling, the ampulla, which functions as a storage organ for endogenous sperm and an oviduct. The accessory genital mass is connected to both the small and large hermaphroditic duct, and consisted of three glands: albumen, membrane (winding) and mucus gland. The albumen gland is consisted of granular cells producing basophilic and neutral mucopolysaccharides. The membrane and mucus gland are consisted of granular cells producing acidophilc and sulfated mucopolysaccharides. The large hermaphroditic duct is a single tubular gonoduct linking the accessory genital mass to the common genital aperture but is consisted of two parallel compartments. Internally, these two compartments are incompletely divided by internal septum or fold, which are called as the red hemiduct and white hemiduct, respectively. The red hemiduct functions as an oviduct and the white hemiduct functions as a copulatory duct. The reproductive system of A. kurodai is externally comprised a single tube, i.e., monaulic type. However, internal structure of duct is incompletely divided into oviduct and copulatory duct, i.e., the oodiaulic type.

• Asian-Australasian Journal of Animal Sciences
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• 제7권1호
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• pp.57-61
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• 1994

The study was conducted at low lying areas in Pabna Sirajgong districts of Bangladesh. To observe the potentiality of bio-mass production two trials were conducted. In first trial maize intercropped with Khesari taking 15 experimental plots of each size $5m{\times}5m$ were arranged in 5 blocks having homogenous soil characteristics. The study showed that the bio-mass yield of sole maize and sole Khesari were 35.25 t/ha. and 56.80 t/ha. respectively and there was a significant difference (p < 0.01) among them. The results also showed that bio-mass yield of maize and Kherasi was higher ($70.04{\pm}6.25t/ha$, $98.88{\pm}10.77t/ha$ and $80.56{\pm}9.5t/ha$) compared to sole maize and sole Khesari and land equivalent ratio was also lower. For second trial, one hectare of land was divided into 16 experimental plots with 4 replications in each plot. Four levels of urea (0 kg/ha, 30 kg/ha, 45 kg/ha, and 60 kg/ha.) were applied to experimental plot. The seed rates were 98.8 kg/ha (farmer's practice), 86.45 kg/ha, 74.1 kg/ha and 61.75 kg/ha. average bio-mass yield of matikalai at different seed rates along with urea fertilizer ranged from 38.49 t/ha, to 65.35 t/ha. the highest seed rate along with highest fertilizer also correspond to the peak production (65.35 t/ha) and the lowest seed rate (61.75 kg/ha) along with the lowest fertilizer rate (30 kg/ha.) showed lowest production (38.49 t/ha.). Here, it was found that the bio-mass yield of matikalai increased with the incremental amount of seed, indicating significant effect (p < 0.05) of seed rates on the bio-mass yield of matikalai. On the other hand, fertilizer doses in different treatment combinations had significant effect (p < 0.05) on bio-mass yield. Two levels of seed rates at zero level of fertilizer were recommended : 86.45 kg/ha for the resource rich farmers and 61.75 kg/ha for the resource poor farmers.

• 한국정밀공학회지
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• 제24권8호통권197호
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• pp.130-137
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• 2007

The optimized prosthetic mass distribution was a controversial problem in the previous studies because they are not supported by empirical evidence. The purpose of the present study was to evaluate the effect of prosthetic mass properties by modeling musculoskeletal system, based on the gait analysis data from two above-knee amputees. The joint torque at hip joint was calculated using inverse dynamic analysis as the mass was changed in knee and foot prosthetic components with the same joint kinematics. The results showed that the peak flexion and abduction torque at the hip joint were 5 Nm and 15 Nm when the mass of the knee component was increased, greater than the peak flexion and abduction torque of the control group at the hip joint, respectively. On the other hand, when the mass of the foot component was increased, the peak flexion and abduction torque at the hip joint were 20 Nm and 15 Nm, greater than the peak flexion and abduction torque of the control, respectively. The hip flexion torque was 4.71-fold greater and 7.92-fold greater than the hip abduction torque for the knee mass increase and the foot mass increase on the average, respectively. Therefore, we could conclude that the effect of foot mass increase was more sensitive than that of knee mass increase for the hip flexion torque. On the contrary, the mass properties of the knee and foot components were not sensitive for the hip abduction torque. In addition, optimized prosthetic mass and appropriate mass distributions were needed to promote efficiency of rehabilitation therapy with consideration of musculoskeletal systems of amputees.

• 대한기계학회논문집B
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• 제32권6호
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• pp.446-454
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• 2008

The purpose of this paper is to analyze two-phase flows of the hydrogen recirculation system. Two-phase flow modeling is one of the great challenges in the classical sciences. As with most problems in engineering, the interest in two-phase flow is due to its extreme importance in various industrial applications. In hydrogen recirculation systems of fuel cell, the changes in pressure and temperature affect the phase change of mixture. Therefore, two-phase flow analysis of the hydrogen recirculation system is very important. Two-phase computation fluid dynamics (CFD) calculations, using a commercial CFD package FLUENT 6.2, were employed to calculate the gas-liquid flow. A two-phase flow calculation was conducted to solve continuity, momentum, energy equation for each phase. Then, the mass transfer between water vapor and liquid water was calculated. Through an experiment to measure production of liquid water with change of pressure, the analysis model was verified. The predictions of rate of condensed liquid water with change of pressure were within an average error of about 5%. A comparison of experimental and computed data was found to be in good agreement. The variations of performance, properties, mass fraction and two-phase flow characteristic of mixture with resepct to the fuel cell power were investigated.

• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.47-49
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• 2012

Massive binary stars lose mass by two mechanisms: jet-driven mass loss during periods of active mass transfer and by wind-driven mass loss. Beta Lyrae is an eclipsing, semi-detached binary whose state of active mass transfer provides a unique opportunity to study how the evolution of binary systems is affected by jet-driven mass loss. Roche lobe overflow from the primary star feeds the thick accretion disk which almost completely obscures the mass-gaining star. A hot spot predicted to be on the edge of the accretion disk may be the source of beta Lyrae's bipolar outflows. I present results from spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and the Flower and Cook Observatory's photoelastic modulating polarimeter instrument which have implications for our current understanding of the system's disk geometry. Using broadband polarimetric analysis, I derive new information about the structure of the disk and the presence and location of a hot spot. These results place constraints on the geometrical distribution of material in beta Lyrae and can help quantify the amount of mass lost from massive interacting binary systems during phases of mass transfer and jet-driven mass loss.

• Structural Engineering and Mechanics
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• 제57권6호
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• pp.989-1014
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• 2016

This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded beam system carrying ends consisting of non-concentrated tip masses and three spring-two mass sub-systems. The influence of system design and sub-system parameters on the combined system characteristics is the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system is included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. Sub-systems are attached to center of gravity eccentric points out of the beam span. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including developed shear force frequency dependent terms, due to the sub.system suspension, have been formulated. Exact formulae for the modal frequencies and the modal shapes have been derived. Based on these formulae, detailed parametric studies are carried out. The geometrical and mechanical parameters of the system under study have been presented in non-dimensional analysis. The applied mathematical model is presented to cover wide range of mechanical, naval and structural engineering applications.

• 국제초고층학회논문집
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• 제10권2호
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• pp.93-97
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• 2021

Supplementary damping systems, such as tuned mass dampers (TMDs) and tuned sloshing dampers (TSDs) - also known as tuned liquid dampers (TLDs) - have been successfully employed to reduce building motion during wind events. A design of a damping system consisting of a TMD and two TSDs performing in unison has been developed for a tall building in Taiwan to reduce wind-induced motion. The architecturally exposed TMD will also be featured as a tourist attraction. The dual-purpose TSD tanks will perform as fire suppression water storage tanks. Linearized equivalent mechanical TSD and TMD models are coupled to the structure to simulate the multi-degree of freedom system response. Frequency response curves for the structure with and without the damping system are created to evaluate the performance of the damping system. The performance of the combined TMD-TSD system is evaluated against a conventional TMD system by computing the effective damping produced by each system. The proposed system is found to have superior performance in acceleration reduction. The combined TMD-TSD system is an effective and affordable means to reduce the wind-induced resonant response of tall buildings.

• International Journal of Control, Automation, and Systems
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• 제2권2호
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• pp.144-155
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• 2004

This paper addresses the issue of position control of a chain of multiple mass-spring-damper (CMMSD) units which can be found in many physical systems. The dynamic model of a CMMSD system with any degrees of freedom is expressed in a closed-form for the convenience of the controller design. Backstepping and model reference adaptive control (MRAC) approaches are then used to develop two adaptive output feedback controllers to control the position of a CMMSD system. The proposed controllers rely on the measurements of the input (force) and the output (position of the mass unit at the end of the chain) of the system without the knowledge of its parameters and internal states. Simulations are used to verify the effectiveness of the controllers

• Journal of Advanced Marine Engineering and Technology
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• 제31권4호
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• pp.335-342
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• 2007

A propulsion and lift shafting system in an air cushion vehicle is flexible multi-elements system which consists of two aeroderivative gas turbines with own bevel gears, four stage lift fan reduction gear, two stage propulsion reduction gear air propellers and high capacity of lifting fans. In addition, the system includes the multi-branched shafting with multi-gas turbine engines and thin walled shaft with flexible coupling. Such a branched shafting system has very intricate vibrating characteristics and especially, the thin walled shaft with flexible couplings can lower the torsional natural frequencies of shafting system to the extent that causes a resonance in the range of operating revolution. In this study, to evaluate vibrational characteristics some analytical methods for the propulsion and lift shafting system are studied. The analysis, including natural frequencies and mode shapes, for five operation cases of the system is conducted using ANSYS code with a equivalent mass-elastic model.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2221-2228
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• 2021

One-dimensional oxygen transport relation is indispensable to study the oxygen distribution in the LBE-cooled system with an oxygen control device. In this paper, a numerical research is carried out to study the oxygen transport characteristics in a gas-phase oxygen control device, including the static case and dynamic case. The model of static oxygen control is based on the two-phase VOF model and the results agree well with the theoretical expectation. The model of dynamic oxygen control is simplified and the gas-liquid interface is treated as a free surface boundary with a constant oxygen concentration. The influences of the inlet and interface oxygen concentration, mass flow rate, temperature, and the inlet pipe location on the mass transfer characteristics are discussed. Based on the results, an oxygen mass transport relation considering the temperature dependence and velocity dependence separately is obtained. The relation can be used in a one-dimensional system analysis code to predict the oxygen provided by the oxygen control device, which is an important part of the integral oxygen mass transfer models.