• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.199-206
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• 2019

This study aims to recycle redmud which is a byproduct in the alumina industry. Redmud ceramics were prepared according to the type of raw materials by blending redmud with the raw materials used in the conventional clay bricks. In this paper, the compressive strength, water absorption ratio, and shrinkage of redmud ceramics prepared by mixing clay bricks were evaluated. Compressive strength and absorption ratio of redmud ceramics were compared with the clay brick criteria of KS L 4201. At the firing temperature of $1200^{\circ}C$, the specimens containing redmud only and the redmud with sandy loam and black clay were found to satisfy the 1st class of clay brick. The quality standard of compressive strength and absorption ratio was obtained by firing redmud with black clay and sandy loam at $1200^{\circ}C$. Also, when the redmud was mixed with black clay and feldspar, the 2nd class was satisfied when the sample was fired at $1100^{\circ}C$.

• 설비공학논문집
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• 제18권9호
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• pp.738-744
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• 2006

In order to utilize the condensation heat of refrigerants in condenser on the absorption chiller system, the solution cooled condenser (SCC) was proposed using the weak solution of absorber as a cooling medium. The increase of COP with the increase of UA of the solution cooled condenser was approximately 0.009 in maximum with single effect one, and is about maximum 0.008 in occasion of double effect one with series flow compared to that without. In the case of heat exchanger, effectiveness is about 0.85, it's increments are 0.008 and 0.0072, respectively. And solution cooled condenser is more effective device in the single effect absorption system than double effect system for the principle of operation. On the other hand, as the solution split ratio increases when the value of UA is fixed, COP is increased and as the solution split ratio increases when the value of UA is fixed, COP is increased. If the flow rate of cooling water or the value of UA is reduced in order to increases the heat recovery of solution cooled condenser, heat recovery of solution cooled condenser is increased a little but COP is decreased as the system pressure is increased.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.744-751
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• 1995

This paper describes a study on absorption properties of electromagnetic wave by the composition ratio of Ni-Zn ferrite. Ni-Zn ferrite was composed of 48-52mol% Fe$\_$2/O$\_$3/, 18-22mol% NiO and 26-34mol% ZnO. The sintering of the composition was carried out at 1200.deg. C for 2 hours. Through the experiments, it was found that the resonance phenomenon occured at low frequency range for high permeability and vice versa. In the case of the composition of 49mol% Fe$\_$2/O$\_$3/, 20mol% NiO and 31mol% ZnO, the bandwidth ranged from 0.35GHz to 0.95GHz with the absorption thickness of 10mm. Also, in the case of the composition 51mol% Fe$\_$2/O$\_$3/, 22mol% NiO and 27mol% ZnO, the bandwidth ranged from 0.48GHz to 1.2GHz with the absorption thickness of 6mm.

• 한국염색가공학회지
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• 제33권1호
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• pp.24-30
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• 2021

In this study, PET containing 3% silver ion-exchange zeolite was mixed with cotton in a ratio of 6:4 to prepare a spun yarn to evaluate the tensile strength, absorption speed, absorption rate, antibacterial property, and the efficiency of deodorization. As a result, the following conclusions were obtained. First, it can be confirmed that silver ion exchange zeolite is evenly distributed inside and on the surface of the antimicrobial PET-SF through SEM. It was found that the tensile strength between the CVC sample mixed with silver ion zeolite PET and cotton and the normal cotton 100% sample was slightly lower in the CVC sample. Although the absorption speed and water absorption rate were measured to find out the moisture characteristics, it was confirmed that there was no significant difference. The contact angle was slightly larger in the antimicrobial CVC sample, but the time it took for the moisture to completely penetrate into the knit fabric was 0.85 seconds. In addition, it was found that out of the total mixing ratio, 40% of antibacterial PET was spun with regular cotton to produce yarn, which had an excellent bacteria reduction rate of 99.9% and a deodorization efficiency of 85%.

• Journal of the Korean Wood Science and Technology
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• 제51권6호
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• pp.470-480
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• 2023

This study aimed to develop a sound-absorbing composite using sugarcane bagasse (SB) and coffee silver skin (CS) as raw materials. The composite boards were manufactured by bonding the fibers with Melamine Urea-Formaldehyde adhesive, ensuring a consistent thickness of 30 mm. Various densities were employed, namely 380, 450, and 520 kg/m³. The samples were fabricated with different fiber ratios, including SB100%, SB75% with CS25%, and SB50% with CS50%. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were measured using the impedance tube method within a frequency range of 63-6,300 Hz. The experimental results revealed that the mixing ratio of CS exerted a notable influence on enhancing the SAC, while the density of the composite board exhibited a significant impact on increasing both the SAC and NRC. Among the densities tested, the optimal value was observed at 520 kg/m³, yielding a SAC value of 0.65 at a frequency of 1,000 Hz and an NRC value of 0.55 for the SB50-CS50 composite plate. These findings underscore the importance of considering the CS mixing ratio and composite board density when aiming to optimize sound absorption properties.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.249-257
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• 2010

In this paper, a three-dimensional hydrogen absorption model is developed to precisely study hydrogen absorption reaction and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The 3D model is first experimentally validated against the temperature evolution data available in the literature. In addition to model validation, the detailed simulation results shows that at the initial absorption stage, the vessel temperature and H/M ratio distributions are uniform throughout the entire vessel, indicating that the hydrogen absorption is so efficient during the early hydriding process and thus local cooling effect is not influential. On the other hand, nonuniform distributions are predicted at the latter absorption stage, which is mainly due to different degrees of cooling between the vessel wall and core regions. This numerical study provides the fundamental understanding of detailed heat and mass transfer phenomena during hydrogen absorption process and further indicates that efficient design of storage vessel and cooling system is critical to achieve fast hydrogen charging and high hydrogen storage efficiency.

• Journal of Pharmaceutical Investigation
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• 제24권3호spc1호
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• pp.59-66
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• 1994

The objective of this study was to determine the influence of drug lipophilicity on the extent of ocular and systemic absorption following topical solution instillation in the pigmented rabbit. ${\beta}-Blockers$ of various lipophilicity were chosen as model drugs, $25\;{\mu}l$ of a 15 mM drug solution in isotonic pH 7.4 buffer was instilled, and ocular tissue and plasma drug concentrations were monitored. Ocular absorption was apparently increased in all eye tissues, but non-corneal absorption ratio was decreased by increasing of drug lipophilicity. Systemic bioavailability was ranged from 61% for atenolol to 100% for timolol, and at least 50% of the systemically absorbed drug reached the blood stream from the nasal mucosa. Occluding the nasolacrimal duct for 5 min reduced the extent of systemic absorption of timolol and levobunolol, but did not do so for atenolol and betaxolol. Taken together, the ocular absorption of topically applied ophthalmic drugs would be modest for lipophilic drugs. By contrast, the systemic bioavailability would be modest for drugs at the extremes of lipophilicity, and the nasal contribution to systemically absorbed drug diminished with increasing of drug lipophilicity.

• 콘크리트학회논문집
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• 제13권6호
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• pp.527-535
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• 2001

SF, ZS 및 SS의 혼합비율을 변화시켜 제조한 구체방수재를 대상으로, 방수재의 종류 및 첨가량에 따른 굳지 않은 콘크리트 및 경화콘크리트의 수밀특성을 분석한 결과는 다음과 같다. 구체방수재의 첨가량이 증가할수록 유동성은 증가하였으며, 응결시간은 지연되었다. 경화상태 압축강도는 기존 제품인 A의 경우, 방수재 첨가량 183kg/㎥까지는 증가하나, 그 이후 24kg/㎥에서는 감소하는 것으로 나타났으며, 시제작품인 B, C, D의 경우는 기존 구체방수재인 A에 비해 높은 강도특성이 있는 것으로 나타났다. 또한, 흡수량은 구체방수재 혼입량이 증가하고, 재령이 경과할수록 적어지는 것으로 나타났는데 특히, ZS의 첨가량이 많은 방수재 일수록 크게 낮아지는 것으로 나타났다. 투수량은 흡수량과 유사한 경향으로, 방수재 첨가량이 증가하고, 재령이 경과할수록 감소하는 등의 특성을 나타내고 있었다. 이상을 종합하여 볼 때 시제작품으로 가정한 SF : ZS : SS의 혼합비가 1 : 2 : 1이고, 혼입량이 63kg/㎥인 조건이면 기존 구체방수재보다 우수한 품질의 수밀콘크리트를 제조할 수 있는 것으로 판단되었다.

• 대한기계학회논문집
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• 제17권8호
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• pp.2099-2109
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• 1993

A gas-fired 4RT absorption heat pump was designed as an air-conditioner for domestic use during the summer. The absorption heat pump is air-cooled. double-effect, $LiBr-H_{2}O$ system with parallel flow type. The performance of the absorption heat pump in the cooling mode of operation was investigated through cycle modeling and simulation to obtain the system characteristics with parameter changes. System parameters considered in this analysis were the inlet temperature of cooling air to the absorber, the working solution concentrations, the ratio of the amount of the weak solution from the absorber, and the LTD's of each heat exchange component. The optimum designs and operating conditions were determined based on the operating constraints and the coefficient of performance.

• 대한기계학회논문집
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• 제19권1호
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• pp.231-239
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• 1995

This paper describes a computer simulation of the triple effect, water-lithium bromide absorption cooling cycles. The performance of the absorption systems is investigated through cycle simulation to obtain the system characteristics with the cooling water inlet temperature, the working solution concentrations, the ratio of the amount of the weak solution to the high, middle and low temperature generators, and the temperature difference of each solution heat exchanger. The efficiency of different cycles has been studied and the simulation results show that higher coefficient of performance could be obtained for the parallel cycle of constant solution distribution rate. As a result of this analysis, the optimum designs and operating conditions were determined based on the operating conditions and coefficient of performance.