• Membrane and Water Treatment
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• 제6권2호
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• pp.113-126
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• 2015

Salinity gradient power (SGP) systems have strong potential to generate sustainable clean electricity for 24 hours. Here, we introduce a solid-salt pressure-retarded osmosis (PRO) system using crystal salt powders rather than seawater. Solid salts have advantages such as a small storage volume, controllable solubility, high Gibbs dissolution energy, and a single type of water intake, low pretreatment costs. The power densities with 3 M draw solutions were $11W/m^2$ with exothermic energy and $8.9W/m^2$ without at 35 bar using a HTI FO membrane (water permeability $A=0.375L\;m^{-2}h^{-1}bar^{-1}$). These empirical power densities are ~13% of the theoretical value.

• 한국재료학회지
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• 제28권7호
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• pp.417-422
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• 2018

The stereotype of flexible MOFs(Amino-MIL-53) and carbonized porous carbon prepared from renewable resources is successfully synthesized for $CO_2$ reduction application. The textural properties of these microporous materials are investigated, and their $CO_2$ storage capacity and separation performance are evaluated. Owing to the combined effects of $CO_2-Amino$ interaction and its flexibility, a $CO_2$ uptake of $2.5mmol\;g^{-1}$ is observed in Amino-MIL-53 at 20 bar 298 K. In contrast, $CH_4$ uptake in Amino-MIL-53 is very low up to 20 bar, implying potential sorbent for $CO_2/CH_4$ separation. Carbonized samples contain a small quantity of metal residues(K, Ca, Mg, S), resulting in naturally doped porous carbon. Due to the trace metal, even higher $CO_2$ uptake of $4.7mmol\;g^{-1}$ is also observed at 20 bar 298 K. Furthermore, the $CH_4$ storage capacity is $2.9mmol\;g^{-1}$ at 298 K and 20 bar. To evaluate the $CO_2$ separation performance, the selectivity based on ideal adsorption solution theory for $CO_2/CH_4$ binary mixtures on the presented porous materials is investigated.

• 대한통합의학회지
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• 제11권4호
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• pp.61-71
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• 2023

Purpose : Energy bars are increasingly popular among active individuals, yet their timing and nutrient combinations' impact on exercise adaptation remains unclear. This study aims to address this knowledge gap by investigating whether the combination of pre- and post-workout supplementation can synergistically enhance fitness and alleviate fatigue in trained CrossFit participants. Investigate if combining pre- and post-workout supplements can enhance fitness and blood lactate management in trained CrossFit participants, potentially improving exercise performance for this group. Methods : In a randomized crossover study, 20 trained CrossFit individuals (11 males, 9 females) completed thrice-weekly 60-minute CrossFit sessions for 3 weeks, with a one-week washout period. Participants were randomly assigned to either a chocolate bar group (CH, 45 g, 225 kcal) or an energy bar group (ES, 48 g, 238 kcal, with protein, caffeine, taurine, and BCAAs). For one week, participants consumed two bars of their assigned supplement five minutes before and after workouts. After a washout period, they switched supplements. Blood lactate levels and a visual analog scale (VAS) were assessed before, immediately after, and 30 minutes post-workout. Fitness tests (hand grip, broad jump, sit-ups) were conducted at baseline and 30 minutes post-final workout. Data were analyzed using two-way repeated measures ANOVA (p<.05), 95 % confidence intervals, and magnitude inferences. Results : Hand grip strength (t=-5.60, p=.000), broad jump (t=-3.43, p=.003) and sit up (t=-3.94, p=.001) were significantly increased in the ES group. Compared to CH group, there was a significant time and group interactions for blood lactate level (F=5.51, p=.008) and VAS(F=31.67, p=.000) in the ES group. Conclusion : Pre- and post-workout energy bar supplementation may have a beneficial effect on blood lactate clearance and fitness in trained CrossFit individual. The combination of proprietary supplements taken may provide benefits for removing the blood lactate during high-intensity functional exercise.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.89-92
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• 1996

In this paper, we developed visual tracking algorithm using double active bar. The active bar model to represent the object can reduce the search space of energy surface and better performance than those of snake model. However, the contour will not find global equilibrium when driving force caused by image may be weak. To overcome this problem. Double active bar is proposed for finding the global minimum point without any dependence on initialization. To achieve the goal, an deformable model with two initial contours in attempted to search for a global minimum within two specific initial contours. This approach improve the performance of finding the contour of target. To evaluate the performance, some experiments are executed. We can achieved the good result for tracking a object on noisy image.

• 한국수소및신에너지학회논문집
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• 제12권1호
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• pp.65-73
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• 2001

Carbon nanotubes were prepared by catalytic decomposition of $CH_4$ using Ni-MgO catalyst at various temperatures. $H_2$ effect on crystallinity and morphology during the synthesis of carbon nanotubes was investigated. The crystallinity and morphology were characterized by SEM, TEM, XRD, TGA, and Raman spectroscopy. In addition, the hydrogen adsorption properties were evaluated by PCT measurement in a hydrogen pressure range between 1 and 120 bar. The optimal synthesis temperature of carbon nanotubes was elevated in the presence of $H_2$, although significant difference of carbon nanotube morphology was not found. It is believed that hydrogen served as self-cleaner mops the amorphous carbon on the catalyst surface. It is proved that the carbon nanotubes have multi-walled structure, short length with a outer diameter of 20 ~40nm and open tips after elimination of the catalyst. The amount of hydrogen adsorbed in carbon nanotubes is increased as the pressure of hydrogen is increased and reaches 1.3 wt % under the hydrogen pressure of 120 bar at room temperature.

• 콘크리트학회논문집
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• 제19권4호
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• pp.411-420
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• 2007

본 연구는 반복 수평 하중을 받는 외부 보-기둥 접합부에서 작은 헤드를 사용한 headed bar의 사용성을 검증하기 위해 $90^{\circ}$ 표준갈고리로 정착한 실험체와 headed bar로 정착한 접합부 실험체를 제작하여 각각의 실험 결과를 비교하였다. 또한, headed bar 정착 성능에 영향을 주는 헤드 단면적, 단조 및 반복 가력 여부, 헤드와 보강근의 용접 여부등의 headed bar 인발 성능에 관한 영향을 구명하기 위한 인발실험을 병행하였다. 인발실험의 결과, headed bar의 인발강도는 헤드 면적 증가에 따라 증가하였고, 헤드와 보강근의 용접 유무, 가력 조건 (단조하중 및 반복하중)은 실험 결과에 큰 영향을 미치지 않는 것으로 나타났다. 외부 보-기둥 접합부 실험의 결과, $90^{\circ}$ 표준갈고리로 정착한 실험체와 headed bar로 정착한 실험체가 초기 균열, 균열의 발생 등 모두 거의 비슷한 양상이었으나, 최종 파괴 시에는 headed bar로 정착된 실험체가 $90^{\circ}$ 표준갈고리로 정착된 실험체에 비해 최대 강도 도달 이후 연성 거동, 연성비 및 변형 성능, 에너지소산 면적 등에서 우수한 거동을 보여주었다. 따라서 ACI 352 위원회의 설계지침을 따라서 제작된 접합부 상세와 동일한 조건으로 표준갈고리 대신 상대적으로 작은 headed bar를 사용할 수 있을 것으로 판단된다.

• 에너지공학
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• 제27권4호
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• pp.80-85
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• 2018

'사용 가능한 흡착량(usable capacity)'은 (굴뚝의)배가스로부터 나오는 $CO_2$를 포집하기 위해 사용되는 흡착제의 성능 평가에 가장 중요하게 여겨지는 매개 변수 중 하나이다. 특히, PSA(압력차 흡착법) 공정에서 '사용 가능한 흡착량'은 고압 (약 20 bar) 배가스에 흡착 양과 낮은 퍼지(purge) 압력 (약 2 bar) 흡착양 사이의 차이로 계산된다. 최근 PSA 공정에 활용 가능한 흡착제로 비표면적이 매우 높은 금속-유기 골격체(MOF)에 대한 연구가 활발히 이루어지고 있다. 따라서 본 논문에서는 대표적인 두 가지 성질(유연 구조화 MOF (MIL-53) 및 강한 결합 부위를 갖는 MOF (MOF-74))을 포함하고 있는 금속-유기 골격체(MOF)를 활용하여 $CO_2$ 포집 성능을 평가 하였다. 20 bar에서의 최대 흡착량은 MOF-74이 MIL-53보다 약 65%이상 높았으나, '사용 가능한 흡착량(usable capacity)'을 계산해 보면, MIL-53이 약 50% 이상 높음을 보여주었다.

• Structural Engineering and Mechanics
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• 제83권6호
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• pp.799-810
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• 2022

This study investigated the effect of the strengthening efficiency of unbonded steel-bar truss system on the out-of-plane behavior of perforated masonry walls. Four full-scale unreinforced masonry (URM) walls with two different planes were prepared using the unbonded steel-bar truss system and a URM walls without strengthening. All masonry walls were tested under constant axial and cyclic lateral loads. The obtained test results indicated that the pinching effect in the out-plane behavior of masonry walls tends to decrease in the in- and out-of-plane strengthened URM walls using the unbonded steel-bar truss system with the higher prestressing force ratio (R_p) of vertical reinforcing bars in the unbonded steel-bar truss system, regardless of the perforated type of the masonry wall. Consequently, the highest maximum shear resistance and cumulative dissipated energy at peak load in the post-peak behavior were observed in the in- and out-plane strengthened URM walls with the highest R_p values, which are 2.7 and 6.0 times higher than those of URM. In particular, the strengthening efficiency of the unbonded steel-bar truss system was primarily attributed to the vertical prestressed steel-bars rather than the diagonal steel-bars, which indicates that the strains in the vertical prestressed steel-bars at the peak load were approximately 1.6 times higher than those in the diagonal steel-bars.

• 한국전기전자재료학회논문지
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• 제32권6호
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• pp.507-511
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• 2019

The purpose of an electric railway system contact wire is to supply electric energy to trains through a contacted pantograph. This energy is then converted into mechanical energy. Recent developments in overhead contact lines include the increase in the tension force up to 34 kN according to train speeds that reach up to 400 km/h with a verified safety. Rigid conductor catenary (R-Bar) for high speeds of up to 250 km/h have been developed in tunnels to save on construction costs. This is significant because minor defects in R-bars in aspects, such as height and stagger affect installation conditions. In this study, we propose the use of a detector that measures the static characteristics to reduce the R-bar installation errors. This detector has been developed to measure the height and stagger of the contact wire using video images.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.274-279
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• 2012

Daegu Solar Power Tower Plant of 200 kW thermal capacity was developed for the first time in Korea, 2011. Measurement of the heat flux distribution is essential to evaluate the solar energy concentrated by reflectors and to design a suitable receiver. The flux mapping technique, which uses a radiometer and a diffuse plate, is common for measurement of the heat flux distribution. Because the solar power tower plant has a wide concentration area, the flux mapping technique using a fixed diffuse plate is difficult to apply. Therefore, the flux distribution in the solar power tower plant should be measured by the flux mapping technique using a small moving bar. In this study, we measured flux distributions with the moving-bar system developed at the KIER solar furnace and evaluated its applicability for the solar power tower plant.