• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.3-11
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• 1999

The atomic fuel rods between top and bottom end pieces of reactor need to be extended for high combustion rate of future-type fuel to increase the irradiation in the axial direction. For allowing axial extension of the fuel rods, the space between top and bottom end pieces should be expanded. Thus the thickness reduction of the flow plate is necessary. This study was carried out the mechanical strength test by using strain gages as a function of flow plate thickness, the existence of skirt and loading condition for the Korean Fuel Assembly(KOFA). The experimental apparatus was designed for load conditions, uniformly distributed load and displacement. Test method using whiffle tree of uniformly distributed load has been comparatively conservative. The test results were compared with those of finite element analysis and the test method on bottom end piece was established.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.438-441
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• 2004

Reduction of a ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargos as well as improving the comfort of the ride. A mass driving anti-rolling system (MD-ARS) might be one candidate of several systems against the ship's rolling. In this paper, a sea-trial test on a pendulum-type MD-ARS passively operated is carried out in Suyoung, Busan. After the system is installed on the cabin of the small leisure boat, a series of test is conducted before and after operating the system. Through the test, it is confirmed that the roll rate of the ship is pretty well reduced by the system.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.1-10
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• 1998

In this paper, we investigated the improvement of characteristics of knock, emission and fuel consumption rate by optimizing the location and size of water transfer holes in cylinder head gasket without change of engine water jacket design itself. The cooling system was modified in the direction of reducing the metal temperature in the head and increasing the metal temperature in the block. The optimization of water transfer holes in cylinder head gasket was obtained by "flow visualization test". The water transfer holes were concentrated in front side of the engine in order to reduce thermal boundary layer in the water jacket of No. 2 and No. 3 combustion changer in the cylinder head, which would have a large knock intensity, and increase thermal boundary layer in the water jacket of the cylinder block. When the modified coolant flow pattern was applied as proposed in this paper, the knock characteristic was improved. The spark timing was advanced up to 2$^{\circ}$ in low and middle speed range at a full load. In addition, HC emission at MBT was reduced by 5.2%, and the fuel consumption rate was decreased up to 1% in the driving condition of 2400 rpm and 250 KPa. However, since this coolant flow pattern mentioned in this paper might deteriorate the performance of vehicle cooling system due to the coolant flow rate reduction, a properly optimized point should be obtained. obtained.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1908-1914
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• 1992

A significant drag reduction in the turbulent flow of CWM(coal Water Mixture) adding minute amounts of high molecular weight polymer additives has been obtained and it was compared with pure CWM.However, the rate of drag reduction could come down with flow time, which is caused by polymer degradation, The rate of drag reduction and polymer degradation is affected by polymer type, concentration, molecular weight, and flow velocity. In the present investigation, these important parameters were evaluated for their influences on polymer degradation in order to find out stable conditions for CWM transportation with time. It was necessary to determine the more effective type of polymer additives to guarantee the optimum conditions for CWM transport. Experiments were undertaken with a test section of pipe diameter 9.8mm and pipe length 3500mm(L/D=357) in a closed loop, and polyacrylamide and polyetylene oxide were utilized as polymer additives. The tests were carried out under the conditions of 200, 400, 700ppm of polymer concentrations. CWM concentrations utilized were 5% and 10% with flow velocities of 4.9m/s and 6.1m/s. Experimental data show that polyehylene oxide degraded faster than polyacrylamide in CWM transport, and polyacryamide is considered to be a more effective candidate as additive for long time-CWM transport. Polymer degradation is also found to be more likely at lower polymer concentrations, at higher flow velocities, and higher CWM concentrations.

• Korean Journal of Human Ecology
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• v.15 no.3
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• pp.481-490
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• 2006

Adjusting pressure level in the construction of athletes' tight-fitting garments by reducing the elastic knit pattern is a challenging subject, which influences the performance of the wearer directly. Therefore, in this study, relationship between the reduction rates of the basic pattern obtained from 3D human scan data and resultant clothing pressure was explored to improve the fit and pressure exerted by clothing. 3D scan data were obtained using Cyberware and they were transformed into a flat pattern using software based on Runge-Kutta method. Reduction rate was examined by subjective wear test as well as objective pressure measurement. As a result, difference in the length between the original 3D body scan data and the 2D tight-fitting pattern was 0.02$\sim$0.50cm (0.05$\sim$1.06%), which was within the range of tolerable limits in making clothes. Among the five garments, the 3T-pattern was superior in terms of subjective sensation and fit. The pressure of the 3T pattern was 2$\sim$4 gf/cm2 at five locations on the body, which is almost the same or a bit higher than that of Z-pattern. In the case of tight-fitting overall garment, the reduction rate of the pattern in the wale direction is more critical to the subjective sensation than the course direction. It is recommended that the reduction grading rules of course direction should be larger than that of Ziegert for a better fit of tight-fitting garments. In the case of wale direction, however, reduction grading rule should be kept the same as suggested earlier by Ziegert (1988).

• Smart Structures and Systems
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• v.4 no.5
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• pp.667-684
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• 2008

Numerous devices exist for reducing or eliminating seismic damage to structures. These include passive dampers, semi-active dampers, and active control devices. The performance of structural systems with these devices has often been evaluated using numerical simulations. Experiments on structural systems with these devices, particularly at large-scale, are lacking. This paper describes a real-time hybrid testing facility that has been developed at the Lehigh University NEES Equipment Site. The facility enables real-time large-scale experiments to be performed on structural systems with rate-dependent devices, thereby permitting a more complete evaluation of the seismic performance of the devices and their effectiveness in seismic hazard reduction. The hardware and integrated control architecture for hybrid testing developed at the facility are presented. An application involving the use of passive elastomeric dampers in a three story moment resisting frame subjected to earthquake ground motions is presented. The experiment focused on a test structure consisting of the damper and diagonal bracing, which was coupled to a nonlinear analytical model of the remaining part of the structure (i.e., the moment resisting frame). A tracking indictor is used to track the actuator ability to achieve the command displacement during a test, enabling the quality of the test results to be assessed. An extension of the testbed to the real-time hybrid testing of smart structures with semi-active dampers is described.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.176-184
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• 2014

Nowadays, consumption of fisheries products is increasing. There are several factors, one of which is a quantitative development through aquaculture. Another factor is an increase qualitative consumption of fish which require that fish be supplied alive. This requires a lot of technical effort to transport the live fish that have low survival rate (c.f. tuna and mackerel) in coastal waters and in the open sea. To develop a towing cage for transporting the live fish, model test in a circulate water channel and simulation by computer tool were carried out. In order to spread vertically, floats were attached at the upper part of the cage, and iron chains attached at the lower part of the cage. For horizontal spreading, kites were attached on the cage. The tension and spreading performance of the cage were measured. The result shows that the tension and reduction ratio of inside volume of the cage were tended to increase with increased towing speeds. The suitable operation condition in towing cage was 1.0 m/s towing speeds with vertical spreading force 8.7 kN, horizontal spreading force 5.6 kN; in this case the reduction ratio of inside volume of the cage was estimated as 25%.

• Journal of Pharmacopuncture
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• v.6 no.3
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• pp.39-47
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• 2003

Background & Methods : In order to measure the acute and subacute toxicity of Vermilionum and it's anti-cancer effects, Sarcoma-180 abdominal cancer cells were injected intravenously. The following results were obtained after measuring the survival rate, toxicity of the NK cells, and IL- 2 productivity. Results : 1. It was impossible to measure $LD_{50}$ value in the acute toxicity test and no toxic effects were witnessed in the clinical observation. 2. No significant differences were shown in the weight changes between the experiment groups and the control group in the acute toxicity test. 3. No peculiar toxic effects were shown in the subacute toxicity test and the weight changes were insignificant between the experiment groups and the control group. 4. In measuring the survival rate after inducing abdominal cancer by Sarcoma-180, the experiment groups showed increased of 9.52% compared to the control group. 5. In measuring the activity of NK cells, no significant changes were shown between the experiment groups and the control group. 6. In measuring the productivity of IL-2, significant reduction was shown in the experiment groups compared to the normal group, but no significance was witnessed compared to the control group.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.308-315
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• 2007

This study is performed to find out the climb performance of light airplane, Chang Gong-91, as a part of flight test to acquire the certification. Chang Gong-91 is a 5-passenger light aircraft of normal category with single reciprocating engine, and the first officially certified by Korean Ministry of Construction and Transportation in 1993. These flight test procedure and data for climb performance are used to get type certification. We have got maximum climb rate for operating altitude, best angle of climb speed, best rate of climb speed, and absolute ceiling of Chang Gong-91 using drag polar data reduction method from sawtooth climb flight data. Also we compare the form drag coefficient from the results of climb performance and Oswald's effectiveness coefficient to design values using lift-drag curve of light airplane.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.541-547
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• 2017

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan Newport including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. Contaminants are accumulated from the sediment release. In this study, before and after dredging the sediment release test was performed. As a result, after the sediment dredging is performed, the reduction rate was higher at the same point. The results show that the water quality can be improved by dredging. Each group (A~C) reduction rate of the evaluation of the reduction rate of 4.64% T-N, 18.00%, 18.59%, respectively. T-P rate of 24.75% reduction, 24.17%, 44.08%, respectively. COD reduction rate was 18.57%, 19.76%, 38.08%, respectively. These results can be used as basic data for controlling the contamination by dredging in Yongwon channel.