• 한국물환경학회지
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• 제22권3호
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• pp.534-539
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• 2006

The supply of oxygen for aeration is the largest energy consumer at activated sludge wastewater treatment plants. Replacement of less efficient aeration systems with fine pore aeration devices can save up to 50 percent of aeration energy costs. The purpose of this study was the diagnosis and evaluation of a domestic wastewater aeration system by the off-gas method which had been studied by US EPA and ASCE. For this study, an off-gas analyzer and its hood were made to collect off-gas. Also, a vacuum pump was connected to the analyzer to make suction of off-gas. Experiments were conducted at a domestic activated sludge wastewater treatment plant which had a single spiral roll aeration system installed with P.E tube diffuser. Data on OTE(f), SOTE(pw), OUR, and air flow rate were obtained from these experiments. In case of replacing an aeration system, it is recommended that it should be replaced with perforated membrane disc or ceramic disc fine bubble diffusers installed in a full floor coverage or grid pattern.

• Journal of Advanced Marine Engineering and Technology
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• 제14권2호
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• pp.35-47
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• 1990

The natural frequency of lateral vibration for ship's propulsion shafting tends to become lower as the relative stiffness of supproted system of the propulsion shafting decreases and the weight of shafting increases. Especially, the propulsion shafting of high-power ships such as car ferries, roll-on/roll-off, and container ships are susceptible to lateral vibration for their resonant speeds are happened to be in ordinary operating speed ranges. So far, many papers on the lateral vibration of ship's propulsion shaftings are published but they treated mainly special cases and not explained explicitly the calculation process. In this paper, the calculation processes of undamped and also forced damped lateral vibration by the transfer matrix method are presented and the calculation programs are developed. With the developed computer programs, a ship's propulsion shafting which was introduced on the published paper is analyzed for its lateral vibration and also the lateral vibration of the main drive shaft for a lathe is calculated to show the availiability of developed computer programs.

• 한국수산과학회지
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• 제56권5호
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• pp.585-595
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• 2023

This study was conducted to optimize the rice paper roll processing conditions with frozen rainbow trout Oncorhynchus mykiss meat (RPR-FRT) treated with polysaccharide and TGase using a response surface methodology and to examine their quality characteristics. The RSM results for the RPR-FRT showed that the optimum condition for the garlic-pepper mixture was 21.2 g and that for starch was 22.6 g based on 150 g of RPR-FRT. The RPR-FRT contained 58.47 g/100 g of moisture, 8.57 g/100 g of crude protein, 3.28 g/100 g of crude lipid, and 1.00 g/100 g of ash. The vitamin E content was 1,010.91 ㎍/100 g. Based on their contents, the samples could be considered good supplements for P, Cr, and Se. The RPR-FRT contained unsaturated fatty acids (75.84%), DHA (10.33%), and EPA (2.56%). Anserine, arginine, glycine, and taurine accounted for 41.93%, 11.27%, 7.13%, and 7.00% of free amino acids in the RPR-FRT, respectively. The sulfur compounds in the RPR-FRT constituted 73.16% of the total flavor compounds. The RPR-FRT prepared using the optimum conditions was superior in masking off-flavor and showed improved nutritional content.

• 한국산업융합학회 논문집
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• 제23권2_2호
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• pp.323-332
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• 2020

Container ships are getting bigger due to the increase in global cargo volume. Therefore, it needs to increase the speed for loading and unloading of containers at the quayside. Traditionally, only one container is handled at once at the quayside due to it's heavy weight. In this paper, a method of handling multiple containers at once using chassis is proposed. Proposed system is consists of a container chassis that can hold three layer stacked containers, transport system that can handle the container chassis including rail-based or vehicle-based roll-on roll-off systems, and dedicated crane system. The conceptual design of crane and transport system that can handle three stacked containers is carried out and verified. The proposed system can be adopted for real quayside container handling system with high speed.

• 한국정밀공학회지
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• 제10권2호
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• pp.170-177
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• 1993

In robotic arc welding, the roll (rotation) of the torch about its direction vector does not have any effect on the welding operation. Thus we could use this redundant degree of greedom for the motion control of the robot manipulator. This paper presents an algorithm for the pseudo- inverse kinematic motion control of the 6-axis robot, which utilizes the above mentioned redunancy. The prototype welding operation and the tool path are also graphically simulated. Since the proposed algorithm requires only the position and normal vector of the weldine as an input data, it is useful for the CAD-based off-line programming of the arc welding robot. In addition, it also has the advantages of the redundant manipulator motion control, like singularity avoidance and collision free motion planning, when compared with the other motion control method based on the direct inverse kinematics.

• ETRI Journal
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• 제23권4호
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• pp.177-189
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• 2001

Multicarrier DS-CDMA is an effective approach to combat fading and various kinds of interference. In this paper, we present an overlapped multicarrier DS-CDMA system, wherein each of the rate 1/M convolutionally-encoded symbols is also repetition coded and transmitted using overlapped multicarriers. However, since the frequency spectrums of successive carriers are allowed to overlap, the transmission bandwidth is more efficiently utilized. The effect of the overlapping percentage between successive carriers of a multicarrier DS-CDMA system on the performance is investigated to determine the overlapping percentage showing the best performance. We suggest two methods for sub-band overlapping variation. One is to allow variation of sub-band overlapping percentage when the total number of subcarriers is fixed. The other is to increase the number of sub-bands (the number of repetitions R) with fixed sub-band bandwidth. Given a total number of subcarriers MR, we show that the BER variation is highly dependent on the roll-off factor ${\beta}$ of a raised-cosine chip wave-shaping filter irrespective of convolutional encoding rate 1/M and repetition coding rate 1/R. We also analyze the possibility of reduction in total multi-user interference by considering the variation of both the roll-off factor ($0<{\beta}{\leq}1$) and the sub-band overlapping factor ($0<{\lambda}{\leq}2$), and show that the proposed system may outperform the multicarrier DS-CDMA system in [3].

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2011년도 춘계학술대회
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• pp.80-81
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• 2011

Canada British Columbia 주의 Prince Rupert 와 Port Hardy(503km) 를 1주일에 2회 왕복하던 Queen of the North 호가 2006년 3월 22일 Gill Island 북쪽 해상에서 좌초되었다. 사고 후, 선박에 탑재된 Electronic Chart System(ECS)을 수거하여 선박의 항해자료를 회수키로하고, 2006년 6월 15일 해양탐사로봇을 이용하여 해저 약 453m 지점에 착저된 선박으로부터 ECS 컴퓨터를 수거하였고 Maker인 Transas사는 수거된 ECS의 Data를 복원하여 선주사에 재공하였다. 이에 따라 캐나다 교통안전국 (Transportation Safety Board of Canada)는 재현 결과물을 통하여 사고원인을 규명한 사건이다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1654-1657
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• 2007

We demonstrate that the reduction of quantum efficiency with increasing current density in phosphorescent light emitting diodes (PhOLEDs) is related to the formation of excitons in hole transporting layer based on the analysis of emission spectra and exciton formation zone. By employing dual emitting layerm we could achieve maintaining quantum efficiency at high current density up to $10000\;cd/m^2$ as 13.1% compared to the devices with single emitting layer (S-EML) (${\eta}_{ext}$= 6.9% at $10000\;cd/m^2$).

• 디지털콘텐츠학회 논문지
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• 제5권4호
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• pp.306-310
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• 2004

본 논문에서는 HDR-WPAN(high data rate wireless personal area network) 시스템에서 TCM-128QAM 변조 방식과 25MHz. 대역폭 확장을 통한 전송용량 향상 방안을 제안하였다. TCM-128QAM의 변조방식을 사용하였을 경우, 15MHz의 대역폭에서 최대 66Mbps의 전송속도를 나타낼 수 있지만, roll-off 계수 ${\alpha}=0.35$으로 하고 대역폭을 25MHz로 확장하였을 경우, 최대 110Mbps의 전송속도를 나타낼 수 있다. 이 같은 결과를 PSD(power spectrum density) 분석 및 BER(bit error rate) 성능을 이용하여 확인하였다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2008년도 한국우주과학회보 제17권2호
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• pp.36.3-36.3
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• 2008

KARI (Korea Aerospace Research Institute) is going to launch a Communication, Ocean and Meteorological Satellite (COMS) at summer of 2009. It will be first thing to be developed for a geostationary satellite through domestic technology. Of course, KARI has performed this development program with EADS Astrium in France since 2005. COMS has the non-symmetric configuration that the solar array is only attached on the south panel. Due to the configuration, momentum of satellite will be rapidly accumulated induced by solar pressure and then 3 wheels of large momentum are located on roll-yaw plane for attitude control. Therefore, to prevent the saturation of wheel momentum, wheel off-loading will be performed two times per day during 10 minutes for each one. At the moment, translation movement on 3-axes direction appears because of using thrusters. In this paper, strategy of the wheel off-loading and triaxiality which is the translation effect on 3-axes are introduced. Consequently, the result of optimized triaxiality considering the wheel off-loading strategy is summarized.