• 한국태양에너지학회 논문집
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• 제29권2호
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• pp.70-75
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• 2009

In this experiment, we did sampling 6 kinds of photovoltaic modules and analyzed the discrepancy of measurement results between l laboratory and 4 PV makers to have performance repeatability at Standard Test Condition(STC) condition. From the KIER's results, Korea's standard test laboratory, other laboratory showed -10% measurement variation. The causes came from correction of reference cell, test condition and the state of skill. Form the comparison test, we analyzed the problems. But three PV maker reduced measurement variation, other one PV maker and one test laboratory didn't improve the problems of correction of reference cell, test condition and the state of skill. Also, High Efficiency Module had a big discrepancy of -10.0$\sim$-6.2% among 3 laboratories which have a less than 10msec light pulse duration time. This made low spectrum response speed so the Fill Factor decreased maximum output power under 10msec light pulse duration time

• 한국지반환경공학회 논문집
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• 제18권11호
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• pp.13-18
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• 2017

단지조성을 위한 성토과정에서 비다짐 시공은 별도의 다짐을 수행하지 않고 장비하중에 의해 다져지게 하는 공법으로 대부분의 현장에서 적용하고 있으나 구체적인 시공지침이나 시방에 명시되지 않아 토공량 평가에 불명확한 점이 있다. 본 연구에서는 단지조성을 위한 지반조성을 수행함에 있어 비다짐 성토지반에 대한 설계 토량환산계수와 실제 토량환산계수 값을 비교하여 타당성 여부를 검토하고 실내시험 및 현장시험, 하중-침하시험 등을 수행하여 합리적인 토량환산계수를 제안함으로써 현장에서의 토공 적정성을 검토하기 위한 기초연구이다. 비다짐 시 토량환산계수 C값은 1.0으로 설계하고 있으나, 현장실험결과 0.86으로 설계보다 작은 것으로 나타나 성토량이 증가될 것으로 예측되었으며, 시공결과 실제로 성토량에 차이가 발생하였다. 따라서 비다짐 성토의 경우 현장여건 및 성토고의 자중을 고려하여 현장조건에 적합한 C값을 실험을 통하여 적용하는 것이 타당할 것으로 판단된다.

• 전기화학회지
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• 제12권1호
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• pp.1-10
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• 2009

This article reviewed transport behaviours of electroactive species in ionic compounds, focusing on chemical diffusion of Li through the transition metal oxide in a current flowing condition. For this purpose, a distinction has been first briefly made between migration and diffusion with respect to current, driving force and charge of electroactive species considered. Then, the equations for chemical diffusion are derived theoretically in open-circuit and current flowing conditions. Finally, the experimental methods such as ac impedance spectroscopy and current (potential) transient techniques are described in details for characterising chemical diffusion. In addition, the role of the thermodynamic enhancement factor in chemical diffusion is discussed.

• 한국태양에너지학회 논문집
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• 제29권6호
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• pp.56-61
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• 2009

The effects of design parameters for small scale hydro power(SSHP) plants due to climate change have been studied. The model to predict hydrologic performance for SSHP plants is used in this study. The results from analysis far rainfall conditions based on KIER model show that the capacity and load factor of SSHP site had large difference between the period. Especially, the hydrologic performance of SSHP site due to rainfall condition of recent period varied in design flowrate sensitively. However climate change gave small effect in load factor of existing SSHP plant. And also, the methodology represented in this study can be used to decide the primary design specifications of SSHP sites.

• International journal of advanced smart convergence
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• 제4권1호
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• pp.64-70
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• 2015

This paper proposes fluorescent electronic ballast with high power factor and low line input current harmonics. The system performance can be improved by a charged pump circuit. Details of design and circuit operation are described. The proposed electronic ballast is modified from single-stage half bridge class D electronic ballast by adding capacitor parallel with each power switch and setting the circuit parameter to operate under class DE inverter condition. By using this proposed method the DC bus voltage can be reduced around by 50% compare with conventional class D inverter circuit. Because the power switches are operated at zero voltage switching condition and low dv/dt of class DE switching. The experimental results show that the proper frequency of the prototype is around 50 kHz with input power factor of 0.982, $THD_i$ 10.2% at full load and efficiency of more than 90%.

• 생명과학회지
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• 제17권8호통권88호
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• pp.1104-1110
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• 2007

2005년 5월부터 2006년 3월까지 안동호와 임하호의 어류상과 서식하는 어종인 끄리(Opsariichthys uncirostris amurensis), 백조어(Culter brevicauda) 그리고 치리(Hemiculter eigenmanni)의 길이-무게 상관관계에 관한 조사 결과를 실시하였으며 결과는 다음과 같다. 조사된 어류는 안동호와 임하호 각각 7과 20종 2,540개체, 4과 11종 850개체였으며, 끄리, 백조어, 치리의 개체수는 안동호에서 총 486개체, 임하호에서는 총 124개 체로 조사되었고, 이들 공서 어류는 길이가 비슷한$({\pm}2.5$ mm) 171개체를 비교하였다. 안동호에 서식하는 끄리, 백조어, 치리의 길이-무게 상관관계식은 각각 TW = $0.000007TL^{3.0543}$, TW = $0.0000009TL^{3.3654}$, TW = $0.000001TL^{3.3872}$로 나타났으며, 임하호에서는 각각 TW = $0.00002TL^{2.8493}$, TW = $0.00001TL^{2.8744}$, TW = $0.000004TL^{3.1082}$로 나타났다. 비대지수에서는 안동호에서는 3종 모두 기울기가 양의 값으로 영양상태가 양호한 것으로 나타났으나, 임하호에서는 치리를 제외한 2종에서 기울기가 음의 값을 나타내어 영양상태가 좋지 않은 것으로 나타났다. 상대적 비대지수를 알아본 결과 끄리와 백조어에서 안동호의 개체가 임하호의 개체보다 비대한 경향을 보였으며, 치리는 임하호의 개체가 더 비대한 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.71-78
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• 2010

The stability analysis of unsaturated infinite slope under rainfall-induced infiltration condition was performed using the generalized effective stress that unifies both saturated and unsaturated condition recently proposed by Lu and Likos(2004, 2006). The Soil-Water Characteristic Curve (SWCC) of the sand with the relative density of 75% was first measured for both drying and wetting processes. The Hydraulic Conductivity Function (HCF) and Suction Stress Characteristic Curve (SSCC) were subsequently estimated. Also, under the rainfall-induced infiltration condition transient seepage analysis of unsaturated infinite slope was performed using the finite element program, SEEP/W. Based on these results, the stability of unsaturated infinite slope under rainfall-induced infiltration condition was examined considering the suction stress. According to the results, the negative pore water pressure and water content within the soil changed with time due to the infiltration. Also, the variation of those caused the variation of suction stress and then the factor of safety of slope changed consequently during the rainfall period.

• 한국환경복원기술학회지
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• 제13권5호
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• pp.51-58
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• 2010

This study was done to recommend a method for conserving the habitat of Amblyotropis verna grown naturally in campus of the Kyungpook National University at Daegu city. Vegetation characteristics and morphological characteristics of each individual were analyzed for the condition of the population at the growing season from May to June in 2010. Totally 11 vegetation data were collected and analyzed, and one vegetation community including Amblyotropis verna (Amblyotropis verna-Zoysia japonica community) was found. We found that the growing condition was not good with severe stamping and disturbance. The location-determining method by PCoA analysis showed the physical texture in soil was a critical factor determining the spatial distribution of the Amblyotropis verna-Zoysia japonica community. And the analysis of morphological characteristics found that light condition and soil hardness were the main ecological factor determining the size and form of each individual. Finally, this study recommend that minimizing impacts by human stamping and artificial disturbance and reducing the water stress were the best ways for the conservation of Amblyotropis verna habitats.

• 설비공학논문집
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• 제29권4호
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• pp.149-158
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• 2017

In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor.

• 한국환경과학회지
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• 제17권5호
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• pp.485-491
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• 2008

The present study examined the relation between land cover condition and temperature in various types of urban green spaces. The diagram of temperature distribution showed that high-temperature zones are formed around paved areas, and low temperature zone around planted areas and grassy areas. Even in planted areas where low-temperature zones were formed, temperature was different according to hierarchical structure. That is, temperature was relatively low in areas covered with arbor + sub-arbor. With regard to land cover ratio, the increase of planted areas and grassy areas had an effect on the fall of temperature and the effect was higher in order of planted areas and grassy areas. On the contrary, paved areas and bare areas had an effect on the rise of temperature. According to the results of factor analysis, in case of the highest temperature, planted area and grassy area were put together into a factor lowering temperature, paved area and temperature into a factor raising temperature, and bare area alone into a factor of low significance. In case of the lowest temperature, grassy area and bare area were put together into a factor, and the validity of the factor analysis was proved by the analysis of urban heat islands. An increase in the number of trees by height was effective in lowering temperature, and the effect was high in order to arbor and sub-arbor, and the source of coldness in planted area was tall trees.