• 한국항행학회논문지
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• 제23권6호
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• pp.570-576
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• 2019

광 네트워크의 융통적 구성을 위해 전체 전송로 중간이 아닌 위치에 존재하는 광 위상 공액기를 갖는 분산 제어 링크를 제안하였다. 제안하는 분산 제어 링크에서 광 위상 공액기는 6개 중계 구간으로 구성되는 전반 전송 구획과 14개로 구성되는 후반 전송 구획 사이에 존재하고, 각 전송 반 구획에서의 평균 중계 구간 당 잉여 분산 (RDPS; residual dispersion per span)이 서로 다른 비대칭 구조이다. 또한 파장 분할 다중 채널의 왜곡 보상을 위하여 각 중계 구간마다 실제 RDPS를 점진적으로 증가/감소시키는 인위적 분포 구조를 채택하였다. 시뮬레이션 결과 제안된 16개의 비대칭 분포 제어 링크 구조 중 인접한 중계 구간 간 RDPS 편차를 적게 하여 전반 전송 구획에서는 중계 구간의 실제 RDPS를 점진적으로 감소시키고 후반 전송 구획에서는 중계 구간의 실제 RDPS를 점진적으로 증가시키는 구조가 왜곡된 파장 분할 다중 채널의 보상에 적합한 것을 확인하였다.

• Journal of Biosystems Engineering
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• 제37권5호
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• pp.314-318
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• 2012

Purpose: This study was conducted to develop a measurement system for determining photosynthetic photon flux (PPF) distribution and illumination efficiency of LED lamps. Methods: The system was composed of a linear moving sensor part (LMSP), a rotating part to turn the LMSP, a body assembly to support the rotating part, and a motor controller. The average PPF of the LED lamp with natural cooling and water cooling was evaluated using the measurement system. Results: The PPF of LED lamp with water cooling was 3.1-31.7% greater than that with natural cooling. Based on the measured value, PPF on the horizontal surface was predicted. Illumination efficiency of the LED lamp was slightly increased with water cooling by 3.4%, compared with natural cooling. A simulation program using MATLAB was developed to analyze the effects of the vertical distance from lighting sources to growing bed, lamp spacing, and number of LED lamps, on the PPF distribution on the horizontal surface. The uniformity of the PPF distribution of the LED lamps was fairly improved with 15 cm spacing, as compared to the 5 cm spacing. By simulation, PPF of $217.0{\pm}27.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was obtained at the vertical distance of 40 cm from six LED lamps with 12 cm spacing. This simulated PPF was compared to the measured one of $225.9{\pm}25.6{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. After continuous lighting of 346 days, the relative PPF of LED lamps with water cooling and natural cooling was decreased by 6.6% and 22.8%, respectively. Conclusions: From these results, it was concluded that the measurement system developed in this study was useful for determining PPF and illumination efficiency of artificial lighting sources including LED lamp.

• Earthquakes and Structures
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• 제16권5호
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• pp.563-573
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• 2019

When generating spectrum-compatible artificial ground motion in engineering practices, the effect of the variation in fitting parameters on the distribution of the peak ground displacement (PGD) has not yet drawn enough attention. In this study, a method for simulating ground motion matching for multiple targets is developed. In this method, a frequency-dependent amplitude envelope function with statistical parameters is introduced to simulate the nonstationarity of the frequency in earthquake ground motion. Then, several groups of time-history acceleration with different temporal and spectral nonstationarities were generated to analyze the effect of nonstationary parameter variations on the distribution of PGD. The following conclusions are drawn from the results: (1) In the simulation of spectrum-compatible artificial ground motion, if the acceleration time-history is generated with random initial phases, the corresponding PGD distribution is quite discrete and an uncertain number of PGD values lower than the limit value are observed. Nevertheless, the mean values of PGD always meet the requirement in every group. (2) If the nonstationary frequencies of the ground motion are taken into account when fitting the target spectrum, the corresponding PGD values will increase. A correlation analysis shows that the change in the mean and the dispersion values, from before the frequencies are controlled to after, correlates with the modal parameters of the predominant frequencies. (3) Extending the maximum period of the target spectrum will increase the corresponding PGD value and, simultaneously, decrease the PGD dispersion. Finally, in order to control the PGD effectively, the ground motion simulation method suggested in this study was revised to target a specified PGD. This novel method can generate ground motion that satisfies not only the required precision of the target spectrum, peak ground acceleration (PGA), and nonstationarity characteristics of the ground motion but also meets the required limit of the PGD, improving engineering practices.

• 산업공학
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• 제11권1호
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• pp.23-32
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• 1998

This paper presents a model for assessing the efficiency of logistics activities in distribution centers. The DEA approach is adopted to compare the relative efficiency of distribution centers, where considered as input and output factors are warehouse floor area, field storage area, average inventory level, overhead costs, number of workers, number of orders, and total value of goods handled. The artificial neural network approach is also adopted to overcome the limitation of DEA. The 12 distribution centers of Korea Telecom are studied for the validation of the model, which results in 84.9% of learning accuracy. This model can be used to identify the inefficient factors in a distribution center and to reveal changes in the degree of efficiency over time.

• 아시안잔디학회지
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• 제10권3호
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• pp.231-246
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• 1996

In order to elucidate the human impact on the distribution of cellular slime molds, samples were collected from 3 types of forest ; natural forests(Mt. Deogyu and Mt. Tsukuba), semi-natural forests(Seoul Great Zoo and Tama Zoo), artificial forests(Seoul National University and Tokyo Gakugei University) .The distribution of cellular slime molds in mountains was different from that of zoo and universities. In mountains, endemic species was occurred and species diversity was higher than in zoo and universities. In zoo and universities disturbed by human, Dictyostelium sphaerocephalum was occurred with higher importance value than in mountains. 6 species were selected to investigate the effect of temperature on froctification; Polysphondylium canlidum, D. delicatum. D. firmibasis, D. sphaerocephalum P. violaceum, D. purpureum. P. violaceum and D. purpureum had an optimum temperature for fructification around 25~3O˚C but the others around 22~23˚C. The degree of sensitivity to temperature was as follows; P. candidum >D. lelicatum > D. firmibasis > D. sphaerocephalum > P. violaceum > D. purpureum. Key words: Human impact, Cellular slime molds, Occurrence and distribution, fructification, Dictylostelium delicatum. Dictyostelium sphaerocephalum.

• 대한전기학회논문지:전력기술부문A
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• 제52권8호
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• pp.463-470
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• 2003

This paper proposes an expert system, which is able to determine the problem-solving strategy for diversity events occurred on the distribution system. The events include events related to the fault, scheduled outage and optimal operating task such as feeder line fault, line scheduled outage, line overload, system load balancing, system loss minimization, main transformer fault, main transformer scheduled outage, main transformer overload, main transformer protection control. The expert system enhances the reliability of software designed by the integrated concept for the diversity events. The expert system is implemented in C language. And the effectiveness and accuracy for the expert system is verified by simulating the event cases for typical distribution model.

• 전기학회논문지
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• 제60권7호
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• pp.1410-1416
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• 2011

A corrosion detecting system for 22.9 kV distribution power line insulation cable, which can travel autonomously along the live line, is proposed. Eddy current test method is employed to detect the corrosion, and the system developed here is capable of detecting internal corrosion of a ACSR-OC. Somewhat details of the electrical and mechanical mechanism of the system and traveling algorithm are introduced. Experimental results applied to the sample cables having artificial corrosion and the operating distribution lines are provided. From the result, we confirmed that the system is useful for detecting internal corrosion of a ACSR, and is expected to be a new non-destructive testing equipment in the area of diagnosis for the distribution power line.

• 대한전기학회논문지:전력기술부문A
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• 제50권4호
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• pp.188-196
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• 2001

This paper presents and efficient algorithm for the loss minimization by automatic sectionalizing switch operation in distribution systems. Ant colony algorithm is multi-agent system in which the behaviour of each single agent, called artificial ant, is inspired by the behaviour of real ants. Ant colony algorithm is suitable for combinatiorial optimization problem as network reconfiguration because it use the long term memory, called pheromone, and heuristic information with the property of the problem. The proposed methodology with some adoptions have been applied to improve the computation time and convergence property. Numerical examples demonstrate the validity and effectiveness of the proposed methodology using a KEPCO's distribution system.

• Journal of information and communication convergence engineering
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• 제22권2호
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• pp.159-164
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• 2024

This study aimed to develop an advanced anomaly-detection system tailored for solar power distribution panels using thermal imaging cameras to ensure operational stability. It addresses the imperative shift toward digitalized safety management in electrical facilities, transcending the limitations of conventional empirical methodologies. Our proposed system leverages a faster R-CNN-based artificial intelligence model optimized through meticulous hyperparameter tuning to efficiently detect anomalies in distribution panels. Through comprehensive experimentation, we validated the efficacy of the system in accurately identifying anomalies, thereby propelling safety protocols forward during the fourth industrial revolution. This study signifies a significant stride toward fortifying the integrity and resilience of solar power distribution systems, which is pivotal for adapting to emerging technological paradigms and evolving safety standards in the energy sector. These findings offer valuable insights for enhancing the reliability and efficiency of safety management practices and fostering a safer and more sustainable energy landscape.

• 수산해양기술연구
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• 제36권2호
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• pp.96-104
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• 2000

본 연구에서는 저자 등이 개발한 인공해저를 대상으로 어류의 위집행동 및 분포구조를 잠수관찰 및 어군탐지기를 이용하여 조사하였다. 인공해저와 같은 해양구조물 주변에서의 군집구조를 파악하는 것은 인공어초의 위집기구 연구에 중요한 사항이다. 연구에서 얻어진 결과를 요약하면 다음과 같다. 1. 잠수관찰에 의하면 어류의 분포층은 인공해저의 구조와 밀접한 관계를 가지고 있어, 표층 해저면에서는 회유성 어종인 고등어, 전갱이가 군을 형성하여 일시적으로 위집되었다. 한편, 중층 시험 어초 부근에는 정착성 어종인 돌돔, 붉바리, 돔감펭볼락 등이 군을 형성 장시간 체류하는 것이 관찰되어, 이들 어류는 인공어초를 먹이장소 또는 휴식공간으로 긴밀하게 이용하고 있다고 판단되었다. 2. 어군탐지기를 사용하여 인공해저 주변을 24시간 항주조사 한 결과, 어류의 행동생태는 일출몰 시각의 전후로 변화하는 것을 알 수 있었다. 주간에 군을 형성하여 인공해저의 중$.$저층 부근에서 유영하던 어군에코는 야간에는 분산형태로 표층부근에 폭 넓게 산재하고 있어, 어군의 일주행동이 분명하게 밝혀졌다.