• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06a
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• pp.3-7
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• 1996

In this paper, the performances of OFDM and MC-CDMA systems in a slowly-varying multipath fading environment is investigated. Time variation of the multipath channel leads to both a change of an optimal coefficient in one-tap equalizer and a loss of subchannel orthogornality, resulting in significant performance loss. A new simple one-tap equalizer which can reduce the effect of slowly time-varying multipath channel is proposed by taking into account time-variation of multipath profile and modifying the previous equalization techniques. It is demonstrated by computer simulation that the performances of OFDM and MC-CDMA systems can be improved by using the proposed one-tap equalizers when the multipath channel is slowly varying.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.55-60
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• 2000

This paper is descried the experimental results of beach process including storm surge and beach recovery. By testing different surge levels and durations, effects of these to shoreline change were evaluated. In addition of beach recovery were investigated experimentally. On the other hand, we proposed the method, which can be applicable to complex hydrograph such as storm surge by modifying equation proposed by Kriebel and Dean. Moreover, applicability of this method is verified by comparing computing result with experiments.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.605-608
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• 2008

In this paper, a numerical investigation of three-dimensional, two-phase flow field around a butterfly valve is conducted. The butterfly valves that have different opening angles, $10^{\circ}{\sim}90^{\circ}$, and two profiles of the shaft boss are compared with various cavitation numbers and Reynolds numbers. This paper focused on the flow analysis in the original butterfly valve and new design butterfly valve in order to decrease cavitation and loss. It is found that the butterfly valve with a cone-type shaft boss greatly reduces the cavitation and loss, compared to the original shaft boss by 20${\sim}$30%.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.148-151
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• 2008

In a double-passage cascade apparatus, only two blades are installed in order to increase the accuracy of experimental result by applying bigger blade than the size of multi-blades on the same apparatus. However, this causes difficulties to make correct periodic condition. In this study, sidewalls are designed to meet periodic condition without removing the operating fluid or adjusting tail boards. Surface Mach number on the blade surface is applied to a responsible variable, and 12 design variables which are related with sidewall profile control are selected. A gradient based optimization is adopted for wall design and CFX-11 is used for the internal flow computation. The computed result shows that it could obtain the same flow structure by modifying only the sidewalls of the double-passage cascade apparatus.

• Smart Structures and Systems
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• v.5 no.6
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• pp.645-662
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• 2009

Adaptive wings are capable of properly modifying their shape depending on the current aerodynamic conditions, in order to improve the overall performance of a flying vehicle. In this paper is presented the concept design of a small-scale compliant wing rib whose outline may be distorted in order to switch from an aerodynamic profile to another. The distortion loads are induced by shape memory alloy actuators placed within the frame of a wing section whose elastic response is predicted by the matrix method with beam formulation. Genetic optimization is used to find a wing rib structure (corresponding to the first airfoil) able to properly deforms itself when loaded by the SMA-induced forces, becoming as close as possible to the desired target shape (second airfoil). An experimental validation of the design procedure is also carried out with reference to a simplified structure layout.

• Archives of Pharmacal Research
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• v.27 no.1
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• pp.1-12
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• 2004

Initial burst is one of the major challenges in protein-encapsulated microparticle systems. Since protein release during the initial stage depends mostly on the diffusional escape of the protein, major approaches to prevent the initial burst have focused on efficient encapsulation of the protein within the microparticles. For this reason, control of encapsulation efficiency and the extent of initial burst are based on common formulation parameters. The present article provides a literature review of the formulation parameters that are known to influence the two properties in the emulsion-solvent evaporation/extraction method. Physical and chemical properties of encapsulating polymers, solvent systems, polymer-drug interactions, and properties of the continuous phase are some of the influential variables. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of the dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.16-21
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• 2013

In this paper, we report the effect of GaN/graded-composition AlGaInN/GaN quantum barriers in active regions on the electrical and optical properties of GaN-based vertical light emitting diodes (VLEDs). By modifying the aluminum composition profile within the AlGaInN quantum barrier, we have achieved improvements in the output power and the internal quantum efficiency (IQE) as compared to VLEDs using conventional GaN barriers. The forward voltages at 350 mA were calculated to be 3.5 and 4.0 V for VLEDs with GaN/graded-composition AlGaInN/GaN barriers and GaN barriers, respectively. The light-output power and IQE of VLEDs with GaN/graded-composition AlGaInN/GaN barriers were also increased by 4.3% and 9.51%, respectively, as compared to those with GaN barriers.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.5
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• pp.179-184
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• 2018

To lessen oxygen concentrations in a wafer through modifying the length of graphite heaters, we investigated the influence of relative distance from heater to quartz crucible on temperature profile of hot-zone in Czochralski silicon-crystal growth by simulation. In particular, ATC temperature and power profiles as a function of different ingot body positions were investigated for five different heater designs; (a) typical side heater (SH), (b) short side heater-up (SSH-up), (c) short side heater-low (SSH-low), (d) bottom heater without side heater (Only-BH), and (e) side heater with bottom heater (SH + BH). It was confirmed that lower short side heater exhibited the highest ATC temperature, which was attributed to the longest distance from triple point to heater center. In addition, for the viewpoint of energy efficiency, it was observed that the typical side heater showed the lowest power because it heated more area of quartz crucible than that of others. This result provides the possibility to predict the feed-forward delta temperature profile as a function of various heater designs.

• Journal of Nutrition and Health
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• v.28 no.9
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• pp.862-871
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• 1995

This study was designed to investigate the effectiveness of ginseng intakes in modifying serum lipid profiles and plasma clotting factors. The participants in this study were 47 normal healthy volunteers(men 24, women 23) with an age range of 35-49 years and a mean age of 41 years residing in Taejon. Based on the diet intakes, subjects were classed into one of three groups : control, vegetarian, and ginseng consumed over 3-4 years. There was no significant difference in their physical characteristics. Dietary calorie intakes were not significantly different in subjects. The ratio of energy intake in the control and ginseng consumed group was 63-64% : 20-21% : 15-16%(Cho : Fat : Pro), but 70-73% : 13-14% :14-15%(Cho : Fat : Pro) in the vegetarians. The intakes of animal food in the vegetarian was significantly lower than the control and ginseng consumed group in men. The ratio of P/S(1.27) was the highest in the vegetarians. Venous blood samples were taken for serum lipid profiling, plasma clotting assay and platelet function. The concentration of serum triglyceride in the men ginseng group is significantly lower than those of the men control group. Serum lipid profiles values of the men ginseng group, such as total cholesterol and phospholipid were lower those of the men control group, but higher those of the men vegetarian group. the serum lipid profile in the women were not significant, but total cholesterol, triglyceride and LDL cholesterol levels in the ginseng groups were low. The concentration of HDL cholesterol was not significantly different. Platelet cell count and platelet aggregation were low in the ginseng groups. APTT(Activated Partial thromboplastin time) was significantly elongated in ginseng groups in the normal range. In seems that the major beneficial effects of ginseng intakes in especially men were on the blood concentrations of triglyceride, total cholesterol and elongation of plasma clotting time.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.5
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• pp.700-711
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• 2017

Objective: The current study aimed to investigate the impact of high-fat diets composed of different animal and vegetable fat sources on serum metabolic health markers in Japanese quail, as well as the overall lipid content and fatty acid profiles of the edible bird tissues following significantly increased dietary lipid supplementation. Methods: Fifty seven male quail were divided into six groups and fed either a standard diet or a diet enriched with one of five different fats (22% coconut oil, lard, palm oil, soybean oil, or sunflower oil) for 12 weeks. The birds were subjected to an oral glucose tolerance test following the feeding period, after which they were euthanized and blood, liver, breast, and thigh muscle samples collected. Total fat content and fatty acid profiles of the tissue samples, as well as serum uric acid, triglyceride, cholesterol, total protein, albumin, aspartate transaminase, and total bilirubin concentrations were assessed. Results: High-fat diet feeding had no significant effects on the glucose tolerance of the birds. Dietary fatty acid profiles of the added fats were reflected in the lipid profiles of both the liver and breast and thigh muscle tissues, indicating successful transfer of dietary fatty acids to the edible bird tissues. The significantly increased level of lipid inclusion in the diets of the quail used in the present study was unsuccessful in increasing the overall lipid content of the edible bird tissues. Serum metabolic health markers in birds on the high-fat diets were not significantly different from those observed in birds on the standard diet. Conclusion: Thus, despite the various high-fat diets modifying the fatty acid profile of the birds' tissues, unlike in most mammals, the birds maintained a normal health status following consumption of the various high-fat diets.