• 한국화재소방학회논문지
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• 제31권1호
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• pp.1-9
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• 2017

본 연구에서는 거실제연설비가 설치된 철도 지하환승통로에 현장성능평가시험인 제연 TAB(Test, Adjusting, Balancing)를 실시하여, 제연설비 성능 확보에 미치는 영향을 분석하고 개선방안을 도출하였다. 제연 TAB는 지하환승통로의 제연설비 설계자료 분석, 제연덕트 누기테스트, 제연송풍기와 덕트의 풍량 및 풍속 측정, Smoke test로 나누어 진행되었다. 제연덕트 누기시험을 통해 누기율을 측정하여 덕트의 기밀성을 확인하였고, 흡입측 덕트 정압손실로 인한 제연풍량 부족의 문제점을 개선하여 송풍기의 성능을 확보하였다. 또한, Smoke test을 통해 예상제연구역별 제연댐퍼 동작 시 자연풍, 열차풍 영향으로 인한 문제점을 분석하고 개선하여 예상 제연구역 내 제연이 원활하게 이루어짐을 확인하였다.

• International Journal of Fluid Machinery and Systems
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• 제8권1호
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• pp.46-54
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• 2015

Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions from thrust bearing and operation conditions of hydro-generator units. Because the oil circulatory and cooling system with thrust-ring-pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump. On another hand, the head and flow rate are varying with the operation conditions of hydro-generator units and the oil circulatory and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulatory and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization is purposed in this paper. Firstly, the head and flow rate at different conditions are decided by 1D flow numerical simulation of the oil circulatory and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and flow rate from the simulation. Thirdly, the flow passage geometry matching optimization between thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulatory and cooling system are collaborative hydrodynamic optimized with predicted head-flow rate curve and the efficiency-flow rate curve of thrust-ring-pump. The presented methodology has been adopted by DFEM in design process of thrust-ring-pump and it shown can effectively improve the performance of whole system.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.27-36
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• 2014

This paper presents a numerical investigation of the effect of the rotation speed on the performance in a transonic axial compressor with the dihedral stator. Four stator geometries with different stacking line variables were tested in the flow simulations over the whole operating range. It was found that a large shroud loss at the rotor outlet and the subsequent shroud corner separation in the stator passage occurred at low mass flow rate with the 100 % design speed. The hub dihedral stator could suppress the shroud loss region and consequently improve the stall margin. In case of the 70 % design speed condition as the mass flow rate decreased, it was seen that the high loss region was placed at the midspan of the rotor passage. The dihedral stator slightly affected the local diffusion factor, but the performance of the compressor was not changed.

• Asian-Australasian Journal of Animal Sciences
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• 제13권11호
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• pp.1499-1507
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• 2000

This trial was to compare the digestive function of laboratory animals, which included omnivores (rats) and herbivores (rabbits, guinea pigs and hamsters). Ten weanling rats, rabbits, guinea pigs and hamster were randomly allocated in individual metabolic cages for a performance and a digestibility trial. Results showed that guinea pigs were significantly best in digestion of dietary crude protein and fiber. Rabbits, however, had the poorest nutrient digestion among the herbivores. Crude fiber digested significantly less by rats than by the herbivores (p<0.05). The digesta retention in the GI tract was longest in rabbits followed by guinea pigs, rats and hamsters. The relative length of the large intestine was significantly shorter in rats as compared to guinea pigs or hamsters. Both the weight and length ratio of the caecum or colon-rectum to the large intestine reflected the major site for fermentation that was the caecum in rabbits and the colon-rectum in guinea pigs. 10% of crude fiber diet did not result in damaged mucosa in any of the experimental animals in this trial.

• 설비공학논문집
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• 제21권3호
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• pp.149-156
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• 2009

A small-scale thermoelectric cooling system was built in an effort to enhance the performance of the refrigeration system by utilizing the water-cooled jacket which was attached to the hot side of the thermoelectric module. Considered design parameters for the water-cooled jacket were the geometry of the flow passage inside the jacket and the flow rate of cooling water. The higher flow rate of cooling water in the jacket resulted in a better performance of the refrigeration system. The increase in the number of channels for water flow passage inside the cooling jacket also showed significant improvement on the performance of the thermoelectric cooling system such as the cooling capacity and the COP of the refrigeration system.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3251-3261
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• 1996

Flows were measured in an unshrouded centrifugal impeller. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes between the inlet and outlet of the impeller rotating at 700 rpm, which diameter is 0.39 meter, and the static pressures and the slip factor at the impeller outlet were estimated from the measured values. Measurements were made for three flow rates corresponding to zero incidence and two others with the greater and the smaller one than zero. From the measured data in these flow rates, the followings were investigated in the impeller passage, the variation of the primary and secondary flows, the leakage flows, the wake's position and its size, the static pressure rise and the loss production mechanism. Furthermore the static pressure and the slip factor were compared with the results of inviscid Quasi-3D calculation.

• 말소리와 음성과학
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• 제10권4호
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• pp.163-171
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• 2018

A mixed dysarthria with combinations of hypokinetic, ataxic, and spastic components is a common clinical feature of multiple system atrophy (MSA). Due to the rapid progress of dysarthria after diagnosis, people with MSA experience difficulty with verbal communication, which eventually affects their quality of life negatively. In this study, SPEAK $OUT!^{(R)}$, an intensive 1:1 treatment of dysarthria for improving functional communicative ability, was provided to twelve people with MSA. To evaluate the efficacy of SPEAK $OUT!^{(R)}$ in people with MSA, aerodynamic, acoustic, and perceptual analyses were conducted. Pre-and post-therapy data included maximum phonation time, vocal intensity, and fundamental frequency during /a/ sustained phonation and passage reading; frequency range between high /a/ and low /a/ phonation; jitter, shimmer, and HNR for vocal quality; speech rate during passage reading; and perceptual evaluation scores for articulation precision and intonation. The participants achieved statistically significant improvement in vocal intensity, pitch range, vocal quality, speech rate, and speech intelligibility. In conclusion, SPEAK $OUT!^{(R)}$ is a feasible treatment for people with MSA to efficaciously improve their speech ability.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.284-289
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• 2002

The objective of this study is to document the secondary flow and the total pressure loss distribution in the contoured endwall installed linear turbine cascade passage and to propose an appropriate height of the contoured endwall which shows the best loss reduction among the simulated contoured endwall. In this study, three different contoured endwalls have been tested which have different height. This study was performed by numerical method and the result showed the contoured endwall which has the height of $5\%$ of the axial chord showed the best loss reduction rate.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.58-63
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• 2003

The performance of turbo pump drops rapidly and it gets into break-down when the void fraction reaches above the threshold value because the impeller flow passage is choked up with air bubbles. Phenomenological understanding of break-down and pumping recovery mechanisms under air-water two-phase flow conditions are therefore important for pump designers and essential assignment for researchers. In this paper, we investigated the characteristics of break-down and pumping recovery due to entrained air occurring inside a screw-type centrifugal pump which has a wide flow passage mainly through the findings of suction and discharge pressures, rotational speed, flow rate measurements and visualization.

• 한국해양공학회지
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• 제5권1호
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• pp.16-24
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• 1991

This paper presents a method of the reliability analysis for a tension leg platform(TLP)in severe storm waves by using the first passage concept of the random tensile stress in the tendons. In the present method, two failure conditions are considered ;i.e., the exceedance of the ultimate tensile capacity and the occurrence of the negative tension. In order to consider the correlation effects between the failure events for each corner resulted from the rupture of all tencons at one corner, a new system limit state for a rectangular shaped TLP is developed, which is defined in terms of the TLP motions in the vertical plane ;i.e., heave, roll, and pitch. To illustrate the validity of the present method, the numerical analysis is carried out for two TLP's with different structural dimensions. Then, the results are compared with those by other methods.