• 인터넷정보학회논문지
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• 제15권2호
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• pp.1-7
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• 2014

본 논문은 MANET망에서 최적의 통달거리를 구하는 분석 수단을 제공한다. 본 연구의 결과는 특히 전술망에서 유용하게 사용 가능하며, 이는 최적 통달거리가 전송용량 및 지연시간, 배터리 소모 등에 영향을 끼치기 때문이다. 더불어, 제안된 분석 수단을 통해 MANET 단말을 휴대한 병사들을 배치하기 위해 사전에 최적 통달거리를 결정하는 것이 가능하도록 한다. 또한, Hata 전파 모델을 기반으로 다양한 전파 환경하에서 배터리 운용시간과 최적 통달거리를 비교/분석한다. 제안된 방안을 통해 MANET망의 운용 환경에 따라 MANET에서 최적 통달거리를 얻는다.

• 전자공학회논문지
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• 제51권4호
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• pp.10-17
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• 2014

본 논문은 MANET 망에서 최적의 통달거리를 구하는 분석 수단을 제공한다. 본 연구의 결과는 특히 전술망에서 유용하게 사용 가능하며, 이는 최적 통달거리가 사용자/라우팅 트래픽 전송용량 및 지연시간, 주파수 간섭 등에 영향을 끼치기 때문이다. 제안된 방안을 적용하여 AODV와 OLSR 라우팅 프로토콜 기반하에 상기 성능지수에 대한 성능 결과값을 분석한 결과, 전술적인 환경 조건을 적용할 경우에 OLSR 프로토콜이 더 우수한 성능을 가짐을 알 수 있다. 또한, OLSR 프로토콜을 적용시 본 논문에서 제안한 최적 통달거리 결과와 기본 통달거리(10km)를 적용한 성능 결과값을 비교하여 본 논문에서 제안한 최적 통달거리 산출 방법이 적정함을 분석한다.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.1-7
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• 1984

The engines mounted on power-tillers are used as power source in various kinds of works such as plowing, harrowing, transporting, spraying, water pumping and threshing, etc. But the engines have not been used effectively from a standpoint of fuel consumption because of lack of proper power transmission system and lack of understanding of fuel consumption characteristics of the engines. Therefore, this study was attempted to establish proper power transmission system between the power-tiller engines and various implements. In order to accomplish the above objective, firstly, power requirement and pulley sizes for various implements, which are driven by the power-tiller engines, were investigated to find out whether the power transmission system is proper. Secondly, partload variable engine-speed test was conducted for 3 different sizes of diesel engines to measure to specific fuel consumption. Thirdly, the present power transmission systems were analyzed in terms of specific fuel consumption, and proper power transmission systems were suggested for various implements. The results of this study are summarized as follows: 1. Power requirement for each fixed-type implement of power-tiller varied from 1.5 ps to 11 ps according to its type and operating conditions, but generally in the range of 2.5 ps to 7 ps. 2. Each power tiller and implement were equipped with only one size of pully with few exeptions. With the present power transmission systems, the engines can't be utilized effectively in terms of fuel economy. The pulley size of engine or implement should be diversified to provide the optimum engine speed for different implements. 3. For a diesel eninge with the rated power output of 6 ps, the optimum engine speed to minimize specific fuel consumption was 2200 rpm for the power reguirement in the range of 6 ps or more, 1700 rpm in the range of 4 to 6 ps, and 1200 rpm in the range of 4 ps or less. 4. For a diesel engine with the rated power output of 8 ps, the optimum engine speed was 2200 rpm for the power requirement in the range of 7 ps or more, 1700 rpm in the range of 4.8 to 7 ps, and 1200 rpm in the range of 4.8 ps or less. 5. For a diesel engine with the rated power output of 10 ps, the optimum engine speed was 2200 rpm for the power requirement in the range of 8.4 ps or more, 1700 rpm in the range of 5.4 ps to 8.4 ps, and 1200 rpm in thr range of 5.4 ps or less. 6. Provided the existing implements are dirven by 8 ps diesel engines, the optimum size of engine pulley should be larger than 120mm for the works of requiring less than 4 ps and 90-110mm for the works requiring 4.5-6.5 ps in order to minimize fuel consumption.

• 소음진동
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• 제9권4호
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• pp.738-746
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• 1999

The performance of muffler can be improved for a frequency range of interest by moving inlet and outlet locations. And optimal location of inlet and outlet can be determined to improve the acoustic performance. The optimum design using FEM, however, may take a very long time and be very hard to take inlet and outlet locations as design variables. In this paper, the acoustic performance of reactive type single expansion chamber muffler is predicted using higher order mode theory. The sensitivity analysis of transmission loss with respect to the location of inlet and outlet is suggested. And the acoustic power transmission coefficient for a frequency of interest is used as cost function. Optimum location of inlet and outlet is determined to minimize cost function by using SUMT algorithm.

• 한국통신학회논문지
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• 제25권9B호
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• pp.1518-1526
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• 2000

본 논문은 기존 표준 단일모드 광섬유 링크를 통하여 초고속 광신호의 장거리 전송이 가능하도록 분산보상 광섬유를 이용한 최적 분산보상 기법에 기반을 둔 전송링크 설계 방법을 제안하였다. 제안한 방법에서는 광섬유의 비선형성에서 비롯되는 자기위상변조(Self-Phase Modulation: SPM)와 광증폭기에서 발생하는 증폭자연방출(Amplified Spontaneous Emission : ASE) 잡음에 대하여 증폭기간 거리와 중계기간 거리를 최적화함으로써 전송신호 속도에 따른 최대 전송거리를 제시하였다. 또한 주어진 증폭기간 거리와 중계기간 거리에 대하여 ASE 잡음과 SPM의 효과의 균형적 관계로부터 최적의 입력 신호전력의 범위가 있음을 제시하였다.

• Fibers and Polymers
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• 제4권2호
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• pp.49-53
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• 2003

Polyurethane (PU) layer and copolymer consisted of the different molecular weights (1000 and 2000 g/mol) of poly(propylene glycol) (PPG) were prepared. The damping and mechanical properties of these materials were compared with PU 1000 made by PPG having the molecular weight of 1000 g/mol. The optimum composition of PU2000 used for PU layer and copolymer was diphenylmethane diioscynate (MDI)/propylene glycol (PPG)/butanediol (BD) (1/0.3/0.7) based on the damping and mechanical properties. The damping peak of PU copolymer was higher than those of PU layer and PUI 1000 in low temperature range (-30- $10^{\circ}C$). For application in noise reduction, the transmission loss of the mechanical vibration through solid structure was measured. PU layer and copolymer were used as a damping layer. The transmission loss of PU copolymer was more effective than those of PU layer and PU 1000 in the experimental frequency range.

• 수산해양기술연구
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• 제49권2호
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• pp.144-152
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• 2013

In an effort to find the optimum porous of Taewoo through the mathematical model 2 - dimensional tank water experiment among the approached to a problem related to ocean engineering, this study analyzed the porosity by dividing it into 9 cases. As the wave penetrates through the longitudinal porous of the Taewoo model, it was found that there is a wave energy loss because of the phenomenon of the separation of the porous due to the eddy. Looking into the general tendency based on the wave-height meter (probe) data, it was found that the shorter wavelength and higher frequency area, the more reflection coefficients increased, but in contrast, the longer wavelength and lower frequency area, the transmission coefficients showed the increasing trend and energy dissipation was in a similar way with reflection coefficients. In addition, it was found that the bigger the porosity was, the narrower distribution range of reflection coefficients was, and the more its average value decreased. On the other hand the transmission coefficients in direct opposition to reflection was found to show the wider range and the more gradual increase in the average value as porosity was the bigger around the average value. In contrast, energy dissipation rate was found to increase linearly as porosity increased the more around the porosity of 0.2518 but it decreased gradually around the peak point. Through the above results, it is judged that the porous of optimum in the longitudinal direction of the Taewoo model perforated plate was about 2.6cm because it was found that the porosity which produced the lowest reflection and transmission coefficient and the highest energy dissipation. As a result of comparing this to the case where there was no porosity at all, it showed the function of wave absorbing about 31.60%.

• ETRI Journal
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• 제9권2호
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• pp.24-35
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• 1987

A Design and Fabrication of 565 Mbit/s Optical Fiber Transmission Link We calculated the transfer functions of optical channel components and formulated the optimum transfer function of optical receiver for optical transmission to show a design rule of fiber optical link for digital transmission. And we evaluated various causes of sensitivity degradation to determine the receiver specification. Also we fabricated and demonstrated a 565Mbit/s single mode fiber optic link, 27km, to show the practicality of designed fiber optic link. The output power of the transmitter was above -3dBm, and the sensitivity of the optical receiver was -37.8dBm which is the same value we expected. Also the dynamic range was more than 25dB.

• 한국기계가공학회지
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• 제15권3호
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• pp.135-146
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• 2016

This study investigated the effect of the changes in metal characteristics due to the hot forging on SCR420HB applied to ensure the optimal production of the hot-forging ratio on the mechanical properties of an automotive automatic transmission gear. The microstructural changes in the forging ratio were investigated by adjusting the forging range into multiple ranges from alloy steel. This was done in order to set the optimum forging range given the manufacturing process conditions during the hot forging of alloy steel parts with a carbon content of more than 0.8% wt. The effects of the content change in the microstructure on the mechanical properties due to the use of the part were examined.

• ETRI Journal
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• 제36권3호
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• pp.374-384
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• 2014

To achieve high-speed (giga-bit) connectivity for short-range wireless multimedia applications, the millimeter-wave (mmWave) wireless personal area networks with directional antennas are gaining increased interest. Due to the use of directional antennas and mmWave communications, the probability of non-interfering transmissions increases in a localized region. Network throughput can be increased immensely by the concurrent time allocation of non-interfering transmissions. The problem of finding optimum time allocation for concurrent transmissions is an NP-hard problem. In this paper, we propose two enhanced versions of previously proposed multi-hop concurrent transmission (MHCT) schemes. To increase network capacity, the proposed schemes efficiently make use of the free holes in the time-allocation map of the MHCT scheme; thus, making it more compact.