• Geomechanics and Engineering
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• 제14권2호
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• pp.151-159
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• 2018

Annually, the global production of construction aggregates reaches over 40 billion tons, making aggregates the largest mining sector by volume and value. Currently, the aggregate industry is shifting from sand to hard rock as a result of legislation limiting the extraction of natural sands and gravels. A major implication of this change in the aggregate industry is the need for understanding rock fragmentation and energy absorption to produce more cost-effective aggregates. In this paper, we focused on incorporating dynamic rock and soil mechanics to understand the effects of loading rate and water saturation on the rock fragmentation and energy absorption of three different sandstones (Red, Berea and Buff) with different pore sizes. Rock core samples were prepared in accordance to the ASTM standards for compressive strength testing. Saturated and dry samples were subsequently prepared and fragmented via fast and dynamic compressive strength tests. The particle size distributions of the resulting fragments were subsequently analyzed using mechanical gradation tests. Our results indicate that the rock fragment size generally decreased with increasing loading rate and water content. In addition, the fragment sizes in the larger pore size sample (Buff sandstone) were relatively smaller those in the smaller pore size sample (Red sandstone). Notably, energy absorption decreased with increased loading rate, water content and rock pore size. These results support the conclusion that rock fragment size is positively correlated with the energy absorption of rocks. In addition, the rock fragment size increases as the energy absorption increases. Thus, our data provide insightful information for improving cost-effective aggregate production methods.

• 대한원격탐사학회지
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• 제39권5_1호
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• pp.551-561
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• 2023

본 연구에서는 Pandora spectrometer system의 태양 직달광 관측 자료로부터 차등흡수분광법(differential optical absorption spectroscopy, DOAS)을 이용하여 포름알데히드(formaldehyde)의 경사칼럼농도(slant column density, SCD)를 산출할 때 스펙트럼 피팅(spectrum fitting) 파장 구간 및 흡수단면적이 산출에 미치는 영향을 조사하였다. 2022년 10월 12일에서 31일까지 서울 연세대학교에서 관측한 Pandora Level 1 자료를 사용하였다. The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2)에서 사용하는 스펙트럼 피팅 파장 구간을 포함한 8가지 범위 및 흡수단면적 구성 7종을 기반으로 포름알데히드 칼럼농도를 산출하였다. 스펙트럼 피팅 파장 구간은 8가지 범위 중 336.5-359.0 nm 구간에서 피팅 후 잔여 신호와 포름알데히드 산출 오차가 최소로 확인되었다. 흡수단면적 구성 7종 중 CINDI-2 캠페인에서 사용하는 흡수단면적에 이산화질소 흡수단면적(220 K)을 추가하여 사용한 경우에 피팅 후 잔여 신호와 포름알데히드 산출 오차가 가장 작았으며 포름알데히드 농도가 안정적으로 산출되었다. 산출 정확도가 가장 높은 경우의 평균 포름알데히드 경사칼럼농도와 그 외 조건들에서 산출된 값들은 최소 4%에서 최대 40%까지 차이를 보였다.

• 벤처창업연구
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• 제15권6호
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• pp.155-166
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• 2020

본 연구는 재창업기업 대표를 대상으로 재창업자의 긍정심리자본 요인인 자기효능감, 희망, 회복탄력성이 흡수역량에 미치는 영향과 재창업자의 흡수역량이 의사결정의 질에 미치는 영향을 고찰하였다. 특히 본 연구는 재창업자에게 심리적 요인들 중 긍정심리자본이 어떠한 영향을 미칠까하는 궁금함에서 출발하였다. 연구대상은 중소벤처기업진흥공단으로부터 재창업 지원자금을 받은 재창업기업 대표를 대상으로 실시하였으며, 조사한 144명의 표본자료를 SPSS 24.0을 활용하여 빈도 분석을 Smart PLS 3.0을 활용하여 구조모형방정식 분석을 실시하였다. 재창업자의 심리적 특성인 긍정심리자본을 자기효능감, 희망, 회복탄력성의 3가지 요인으로 구분하여, 잠재적 흡수역량과 실행적 흡수역량에 미치는 영향을 분석한 결과, 자기효능감은 잠재적 흡수역량에 긍정적인 영향을 미치는 것으로 나타났고, 실행적 흡수역량에는 영향을 미치지 않는 것으로 나타났으며, 희망은 잠재적 흡수역량에 영향을 미치지 않는 것으로 나타났고, 실행적 흡수역량에는 긍정적인 영향을 미치는 것으로 나타났다. 회복탄력성은 잠재적 흡수역량 및 실행적 흡수역량에 긍정적인 영향을 미치는 것으로 나타났다. 그리고 잠재적 흡수역량 및 실행적 흡수역량은 의사결정의 질에 긍정적 영향을 미치는 것으로 나타났다. 이와 같은 연구결과를 바탕으로 실무적 시사점과 이론적 시사점을 제공하고자 한다.

• 설비공학논문집
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• 제18권7호
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• pp.556-562
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• 2006

The objectives of this paper are to analyze simultaneous heat and mass transfer performance for a plate type bubble absorber with binary nanofluids numerically and to investigate the effects of binary nanofluids and surfactants on the size of the bubble absorber. The effective absorption ratio represents the effect of binary nanofluids and surfactants on the absorption performance. The kinds and concentrations of nano-particles and surfactants are considered as the key parameters. The results show that the addition of surfactants can reduce the size of absorber up to 74.4%, the application of binary nanofluids does the size up to 63.6%. Combination of binary nanofluids and surfactants can reduce the size of absorber up to 77.4%.

• 한국식품영양과학회지
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• 제10권1호
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• pp.107-116
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• 1981

This experiment was attempted to establish the optimal condition, e.g., the effects of pH, interferences of other elements, for the determination of the inorganic elements in the paddy soils by atomic absorption spectrophotometry. Inorganic elements of 100 paddy soils which were sampled in Jeon bug provincial farm land were determined by atomic absorption spectrophotometer in that condition. The results obtained in this experiment are summarized as follows: 1) The optimal pH for determination of inorganic elements in paddy soils is about 7.0. 2) It was investigated that the absorbance of potassium was increased, and that of calcium, magnesium and zinc was decreased by adding of $Fe^{++}$ and $Cu^{++}$ in the sample. 3) It was shown that paddy soils in Jeonbug provincial farm land contain the normal amounts of inorganic elements (K, Ca, Mg, Zn,). But comparing to the results of 1976 year, it was known that the contents of inorganic elements in paddy soils considerably was changed.

• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.490-496
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• 2018

Recently, the power and refrigeration cogeneration based on Kalina cycle has attracted much attention for more efficient utilization of low-grade energy. This study presents a thermodynamic performance analysis of a cogeneration cycle of power and absorption refrigeration based on Kalina cycle. The cycle combines Kalina cycle (KCS-11) and absorption cycles by adding a condenser and an evaporator between turbine and absorber. The effects of ammonia mass fraction and separation pressure were investigated on the system performance of the system. Results showed that the energy utilization of the system could be greatly improved compared to the basic Kalina cycle.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.415.2-415.2
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• 2002

We investigated the absorption enhancing effect of BuOH extract of the root of Aralia elata (BERAE) in Caco-2 cell monolayers and rats. At the concentration of both 0.04% and 0.08% (w/v). BERAE decreased the transepithelial electrical resistance (TEER) values and increased the permeability of intact chondroitin sulfate (CS) and its digestion products as hydrophilic macromolecules in a dose dependent manner. We also evaluated the cytotoxicity of BERAE for the determination of a proper concentration as an absorption enhancer. (omitted)

• 동의생리병리학회지
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• 제24권6호
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• pp.921-923
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• 2010

Although Bi(脾 Spleen) is a major organ which controls digestion and absorption in Korean medicine, there also introduced another function of bi, which is called 'bitonghyul(脾統血)' that means the spleen controls(holdings) the blood. While the spleen is involved in the function of blood generation through the digestion and absorption of food, 'bitonghyul' is another expression regarding function of the spleen. The meaning of 'bitonghyul' is related with the function of keeping the blood flowing within the blood vessels, hemostasis. Comparing the function of the spleen with the mechanisms of hemostais, it is concluded that 'bitonghyul' is a physiological effects which affect hemostatic mechanisms via absorption of vitamin K.

• Journal of electromagnetic engineering and science
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• 제9권1호
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• pp.46-52
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• 2009

This paper conducts a study on the frequency-dependent filtering and blocking effects of a variety of periodic structures, dubbed frequency selective surface(FSS). The periodic structures of interest are 1D and 2D repeated patterns of metal patches or slots sitting on the interface between the two different regions in the layered media which will show the capacitive or inductive behaviors and incorporated with the electromagnetic bandgap(EBG) geometry as another stratified media. Besides the normal substances so called double positive(DPS)-type in the layered media, metamaterials of double negative(DNG) are considered as layering components on the purpose of investigating the unusual electromagnetic phenomena. Frequency responses of transmission(absorption in terms of scattering) and reflection will be calculated by a numerical analysis which can be validated by the comparison with the open literature and demonstrated for the periodic structures embedding metamaterials or not. Most importantly, numerous examples of FSS will present the useful guidelines to have absorption or reflection properties in the frequency domain.

• 설비공학논문집
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• 제13권9호
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• pp.878-887
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• 2001

Experimental investigation has been carried out to examine the operating characteristics of a bubble pump for diffusion absorption refrigerator. The effects of heat input and delivery height on generation rate of refrigerant vapor and circulation rate of solution have been investigated. as a result heat input and delivery height increase, circulation rate of solution increases. And the smaller the tube diameter, the larger the circulation rate of solution. Pumping ratio increases to a critical point and then decrease with the increase of heat input, and it increases with the increase in delivery height. In this paper, Marcus's analytical theory was also examined. It was found that the Marcus\`s analytical theory of a bubble pump was not appropriate for a bubble pump using ammonia aqueous solution as a working fluid.