• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.3-5
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• 2006

In this paper, annual energy production(AEP) of the wind generator system is analogized considering the regions of a variable wind speed and it is applied to optimal design of the PM wind generator for capturing maximum energy in the operating regions. In addition, internet parallel computing is used to loose excessive calculation times through optimization of the finite element analysis(FEA).

• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.111-118
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• 2007

This study was performed to measure gaseous Organochlorine Pesticides (OCPs : heptachlor epoxide, ${\alpha}/{\gamma}-chlordane$, trans-nonachlor, endosulfan, ${\gamma}-HCH$ and p, p'-DDE) concentration using PUF high volume sampler from June, 2000 to June, 2002 in the semi-rural atmosphere. Using monitoring data for two years, we tried to investigate the annual cycles of gaseous OCPs. We considered three functions to describe the annual cycle: Gaussian, Lorentzian and sinusoidal functions. These functions accounted for $54{\sim}91%$ of the variability in concentration for each gaseous OCPs, and the sinusoidal function gave the best fits. It was seen that the gaseous OCPs concentration increased during the warmer weather while decreased during colder weather. The variation of the gaseous OCPs concentration was closely similar to the variations of ambient temperature. The annual cycle of endosulfan was strongly higher than in comparison with other gaseous OCPs, while for ${\gamma}-HCH$, the cycle was weakly high and did not show apparent seasonal variation. The position of the annual maximum exists generally late July to early August. The period that showed levels more than a half maximum was from late June to early September.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2223-2235
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• 2013

This study aimed to understand temporal and spatial trends of rainfall characteristics in South and North Korea. Daily rainfall observed at the 65 stations in South Korea between 1963 and 2010 and the 27 stations in North Korea between 1973 and 2010 were analyzed. Rainfall Indicators for amount, extremes, frequency of rainfall were defined. Province-based indicators in the recent 10 years (i.e., between 2001 and 2010) were compared to those in the past (i.e., between 1963/1973 and 2000 for South/North Korea). In the recent 10 years, all the indicators except for the number of wet days (NWD) and 200-yr frequency rainfall (Freq200) increased in South Korea and all the indicators except for the annual mean daily rainfall over wet days (SDII) and annual total rainfall amount (TotalDR) decreased in North Korea. Furthermore, we performed the Mann-Kendall trend test based on the annual indicators. In some stations, decreasing trends in the past and increasing trends in the recent 10 years were found, and such opposite trends between two periods suggest he limitation in predicting and analyzing the rainfall characteristics based on the average. Results from this study can be used in analyzing the impact of climate change and preparing adaptation strategies for the water resources management.

• Current Photovoltaic Research
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• v.6 no.3
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• pp.69-73
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• 2018

PV system is consisted with PV module, inverter and BOS(balance of system). To have robustic operation more than 20 years, the expected and guaranteed durability and reliability of products should be met. Almost components of PV system are qualified through IEC standards at test laboratory. But the qualification certificate of product does not ensure long-term nondefective operation. PV module's expected life time is nowadays more than 20 years and annual maximum power degradation ratio would be less than -1%. But the power degradation ratio is basically based on real data more than several years' record. Developing test method for ensuring annual maximum power degradation ratio is very need because there are many new products every month with new materials. In this paper, we have suggested new test method under continuous artificial light irradiation test condition for analyze expected maximum power drop ratio.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.8-12
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• 1985

In the pure Phragmites communis grassland in the lower course of Nakdong river, the seasonal changes of standing crop and productive structure, annual changes of the maximum standing crop, and annual net production were estimated. The maximum standing crop of the pure P. communis grassland is on mid-September, the maximum average daily productivity was $32.7g/m^2/day$ from June to July. The leaf area index of the pure reed grassland increased to July, and then decreased slowly. The logitudinal growth of above-ground parts of the reed grassland was maximum state, 320cm, on mid September. Annual net production was $3,399g/m^2/year$, and it suggests that grassland is stable. Productive structure of the pure reed grassland indicated that the distribution of leaf was concentrated on the upper parts according to the grassland maturation.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.2
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• pp.97-104
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• 2019

The purpose of this study was to establish the estimation method of irrigation water amount for sewage treated water reuse for agricultural purpose. To calculate the irrigation water amount, we adopted Penman-Monteith for potential evapotranspiration estimation and applied crop coefficient and irrigation efficiency factor. We developed the irrigation water amount calculation program using C language in Xcode environment. The target district for calculation is having 259 ha of agricultural land located near the Jinyeong Clear Water Circulation Center in Hanrim-myeon, Gimhae city. The meteorological data of the study area were obtained from Changwon weather station from 1986 to 2017. Calculated average and maximum of annual mean potential evapotranspiration were 2.72 mm/day and 6.22 mm/day, respectively. We used K-S (Kolmogorov-Smirnov) for goodness-of-fit test to find optimal probability distribution of annual mean and maximum evapotranspiration. As a result, the normal distribution was selected for the appropriate distribution. The annual mean and maximum potential evapotranspiration for 10-year return period by applying normal distribution were 2.88 mm/day and 6.76 mm/day, respectively. Assuming that the irrigation efficiency is 80%, the irrigation water requirement was calculated as $36.05m^3/day/ha$ and $84.45m^3/day/ha$, respectively, when annual mean and maximum potential evapotranspiration were applied. The actual irrigation water amount can be calculated by applying the crop coefficient and cropping days for the study area based on the developed irrigation water amount estimation program in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.519-528
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• 2006

In the construction of hydraulic structures deciding a design flood is one of the most important works. It should be especially noted that the time distribution of the design rainfall method makes a significant effect on the results of the design flood. Thus, choosing an appropriate time distribution method for the design rainfall is a very important process. In recent years, Huff's method is usually used in Korea. This method presents dimensionless rainfall-time cumulative curves, which are made through the analyses of storm data. In this study, the annual maximum rainfall data, from 1961 to 2004 were analyzed to make the dimensionless rainfall-time cumulative curves and hyetographs in Seoul. The results were compared with the "Regional Time Distribution of the Design Rainfall", (KICT, 1989 and MCT, 2000). As a result, the dimensionless rainfall-time cumulative curves are smoother than Huff's results when the duration of an annual maximum rainfall is short. In addition, the curves are similar with the Huff's results as the duration is longer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.515-524
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• 2008

An estimation of reliable probability precipitation is one of the most important processes for reasonable hydrologic structure design. A probability precipitation has been calculated by frequency analysis using annual maximum rainfall series on the each duration among the observed rainfall data. Annual maximum rainfall series have abstracted on hourly rainfall data or daily rainfall data. So, there is necessary to proper conversion factor between the fixed and sliding durations. Therefore, in this study, conversion factors on the each duration between fixed and sliding durations have calculated using minutely data compared to hourly and daily data of 37 stations observed by Meteorological Administration in Korea. Also, regression equations were computed by regression analysis of conversion factors on the each duration. Consequently, conversion factors were used basis data for calculations of stable probability precipitation.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.211-225
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• 2013

To run an optimal operation of Integrated energy supply facilities, we need to analyze heat consumption patterns of District heating users and derive optimum and maximum load ratio of heat production facilities unit. This study selects three District heat production facilities. It also classifies District heating users into residential apartment buildings and eight non-residential buildings and analyzes heat consumption results for an year. Finally it carries out the analysis of how the ratio change of each type affects maximum load ratio, facility utilization ratio, heat supply range. According to this study, three different District heat facilities of residential apartment building show similar daily and annual heat consumption patterns. Annual average load ratio, maximum load ratio and annual heat demand increase as outdoor temperatures decrease. Non-residential buildings in urban District focused on apartment buildings display similar by the daily and annual heat consumption patterns. Yet their daily and annual maximum load ratio differ according to outdoor temperature, District, building types and their composition ratio. In the case of urban District focused on apartment buildings reach optimum and maximum load ratio when apartment buildings reaches 60-70% of the total. At that point heat supply range becomes maximized and the most economic efficiency is obtained.

• Korean Journal of Hydrosciences
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• v.4
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• pp.51-63
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• 1993

This study is to verify the applicability of statistical models in predicting flood frequency at the stage gaging stations of which the flow is under natural condition in the Han River basin. The results of the study show that the statistical flood frequency models were proven to be fairly reasonable to apply in practice, and also were compared with sampling variance to calibrate the statistical efficiency of the estimators of the T year floods Q(T) by two different flood frequency models. As a result, it was showed that for return periods greater than about T = 10 years the annual exceedance series estimators of Q(T) has smaller sampling variance than the annual maximum series estimators. It was showed that for the range of return periods the partial duration series estimators of !(T) has smaller sampling variance than the annual maximum series estimate only if the POT model contains at least 2N(N : record length) items or more in order to estimate Q(T) more efficiently than the ANNMAX model.