• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.74.2-74.2
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• 2010

전세계는 $CO_2$ 규제강화와 에너지의 효율적 사용에 대한 사회적, 경제적 요구가 증대되면서 친환경 에너지 설비와 지능형 전력망(smart grid)가 크게 예상되고 있다. 이에 따라 기존 내연기관에 근거한 발전산업 및 자동차 산업은 필연적으로 청정에너지 기반의 전기에너지로 점진적으로 대체될 것으로 판단된다. 따라서, 청정 발전 시스템의 보급 확대와 기존 에너지의 효율적 사용을 위해서 2차전지 기반의 전력저장 기술과 연료전지 기반의 분산발전 기술이 향후 미래에너지 산업의 근간이 되는 중요한 기술들로 부상하게 되었다. 아연/공기전지는 현재는 연료전지 개념의 1차전지에 기술수준이 머물러 있지만 향후 미래에는 기존의 리튬이온전지의 낮은 에너지밀도를 극복할 수 있는 미래 2차전지 기술의 하나로 평가받고 있다. 본 연구에서는 이러한 연료전지 개념의 아연/공기전지에 대하여 기존의 수소연료전지 기반의 분산발전 분야에 적용한다면 약 1/10 이하의 가격으로 조기에 시장진입이 가능할 것으로 판단하여 사전 타당성 연구 및 대면적화를 위한 기초 설계인자 연구를 수행하였다. 연구결과, 소형 단전지부터 약 800cm2까지의 대면적 단전지까지 대면적화를 위한 기초연구를 실시하였으며, 4개의 cell로 구성된 최고출력 90W급 전해질 순환형 미니스택 시스템을 구성하여 발전시스템으로서의 가능성과 문제점 등을 도출하였다. 이러한 시험결과를 바탕으로 25개의 cell로 구성된 약 1kW 급 스택을 설계하여 향후 소형 발전시스템을 제작하고자 하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.665-674
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• 2015

A TSL (Thin Spray-on Liner) which consists of polymers has a higher initial strength, faster construction time and higher waterproofing performance than the conventional cementitious shotcrete. Main supporting mechanism of TSL is the adhesion and tensile strength which is distinct from the conventional shotcrete. Even though highly in demand due to its outstanding characteristics, TSL is not yet well-known support material. In this study, to evaluate contact behavior of TSL, numerical analysis was performed with comparing result from laboratory tests. From the analysis, cohesive behavior at the contact surface between TSL and rock can be evaluated by using combination of cohesive and the damage model. In addition, results show that the cohesive stiffness controled slope between force and displacement, the fracture energy controled level of force at the contact.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.4
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• pp.369-375
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• 2012

In order to overcome the detection limit by the current nondestructive evaluation technology, a nonlinear resonant ultrasound spectroscopy(NRUS) technique was applied for detection of micro-scale cracks in a material. A down-shift of the resonance frequency and a variation of normalized amplitude of the resonance pattern were suggested as the nonlinear parameter for detection of micro-scale cracks in a materials. A natural-like crack were produced in a standard compact tension(CT) specimen by a low cycle fatigue test and the resonance patterns were acquired in each fatigue step. As the exciting voltage increases, a down-shift of resonance frequency were increases as well as the normalized amplitude decrease. This nonlinear effects were significant and even greater in the cracked specimen, but not observed in a intact specimen.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.173.2-174
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• 2003

국내 보급되고 있는 곡물건조기는 열풍형 순환식 곡물건조기가 주종을 이루고 있는데, 이건조기의 경우 곡물이 순환하면서 열풍공급과 템퍼링과정을 반복하면서 건조가 이루어지는 대류열전달 방식을 채택하고 있다. 대류열전달 방식은 복사열전달 방식에 비해 열전달률이 낮기 때문에 건조속도와 열효율이 떨어지며, 건조시 미질 향상과 건조비용 절감에 한계가 있어 왔다. 따라서 건조에너지의 절감과 동시에 고품질 쌀 생산을 할 수 있는 새로운 형식의 곡물건조기술을 확립하고자 원적외선 곡물건조기를 개발하였다. 원적외선은 0.56~l,000$\mu\textrm{m}$의 전자파로서 세라믹 도료표면에 열을 가하면 원적외선 파장대의 강한 에너지를 얻을 수 있다. 이같은 원적외선 에너지를 농산물에 조사시키면 열이 침투하게되고 동시에 농산물의 내부온도가 상승함에 따라 활발한 분자운동을 하면서 수분을 표면으로 이동시키기 때문에 열풍건조방법에 비해 열전달효율이 높고, 농산물을 보다 균일하게 건조가 가능하므로 좋은 품질의 쌀을 생산할 수 있는 특징을 가지고 있다. 시작기는 1회 3,800kg을 건조할 수 있도록 설계하였고, 템퍼링실, 건조실, 열풍실, 승강기 등으로 구성되었다. 원적외선 방사체의 형태는 실린더형이고, 방사체가 설치된 열풍실 위쪽은 타공망, 아래쪽은 방사량을 높이기 위하여 일부 개방된 구조로 제작하였다. 본 연구에서 구명된 원적외선 방사체 길이와 조사거리는 각각 1,470mm, 125mm가 적절한 것으로 나타났다. 시작기의 성능시험을 열풍건조기(대비구)와 비교한 결과 소음은 대비구에서의 94.12dB보다 13% 가량 낮게 나타났고, 건조온도를 45$^{\circ}C$로 설정하고 벼를 건조했을 때 건감률 0.58%,wb로 대비구의 0.47%,wb 보다 23% 높았고, 건조소요에너지도 470kcal/kg - water로 2%의 절감되었다. 또한 건조한 벼를 도정하여 색, 냄새, 윤기, 찰기 등에 대한 관능검사결과는 원적외선 건조방법이 종합기호도가 6.37으로 열풍건조방법 6.13보다 우수한 평가를 받았다. 건조비용은 시작기의 구입가격이 20% 비싸기 때문에 시간당 고정비가 높았으나, 건조성능이 우수하여 건조비용이 69,350원/톤으로 대비구보다 14% 절감되는 것으로 나타났다.

• Journal of Korean Association for Spatial Structures
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• v.7 no.1 s.23
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• pp.79-85
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• 2007

Steel plate bonding method with epoxy is common applied to repair and strengthen RC structures, but Steel is apt to corrode quickly, hard to manufacture and heavy. To overcome these defects, it is carried out research on strengthening RC structures with FRP(Fibre Reinforced Polyrner/Plastic) FRP is generally used in the shape of Plate or Sheet, but it has weak point such as premature failure, difficult work. To cope with these problem, NSMR(Near Surface Mounted Reinforcement) which uses CFRP in the shape of Rod is proposed and carried out active research on strengthening effect of variables such as quantity, anchorage length and space of CFRP-Rod. Strengthening with CFRP-Rod is carried out under loading to some degree in fact, and so the amount of pre-loading is selected as variable in this research. The amount of pre-loading is chosen in proportion to nominal strength of non-strengthened specimen with CFRP-Rod.

• Korean Journal of Food Science and Technology
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• v.26 no.3
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• pp.199-203
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• 1994

Software for refrigerator capable of both rapid fermentation and suitable storage of Kimchi was developed and its performance was investigated. Refrigerator system consists of an insulated fermentation room, heater, damper for the control of outer cold air and two sensors for recognizing temperature of heater and fermentation room, which control temperature and time period of affecting Kimchi fermentation. Effects of fermentation at different NaCl concentration and three fermentation function keys were studied; At key I, time which was elapsed to edible ripening state, pH 4.5 and total acid 0.6%, was about $3{\sim}4$, $4{\sim}5$ and $11{\sim}12$ days, respectively. At key II, time was about $2{\sim}3$, $3{\sim}4$, and $10{\sim}11$ days, and at key III, about 2, 3 and $9{\sim}10$ days, respectively. Effect of storage at three fermentation function keys was all maintained to the level of a palatable pH range until 14 days. Sensory evaluation of Kimchi showed also significant difference in a taste.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.47-54
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• 2017

Cement industry is typical carbon-emission industry. If the industrial by-products(granulated blast-furnace slag (GGBFS), fly ash, etc.) are used a large amount, it might be able to reduce cement consumption and mitigate carbon emissions. In this case, however, decrease of early strength is relatively large. Therefore, there is a limitation in increase of the amount of substitute. Considering these circumstances, it would be a good solution to reduce carbon emissions in cement industry to improve the performances of mixed cement through proper alkali-activation in Portland blended cement using GGBFS or fly ash. Therefore, this study prepared concrete in ready-mixed concrete manufacturing facilities with an addition of a binder which used 2.0% modified alkali sulfate activator after mixing Portland cement, GGBFS and fly ash in the ratio of 4:4:2 and assessed its basic properties. The results found the followings: The use of modified alkali-sulfate activator slightly reduced slump and shortened setting time. As a result, bleeding capacity decreased while early strength improved. In addition, there is no big difference in carbonation resistance. It appears that there should be continued experiments and analyses on the related long-term aged specimens.

• Journal of the Korea Institute of Building Construction
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• v.14 no.2
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• pp.156-162
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• 2014

This study aims to develop a rapidly hardening type of concrete to achieve the removal of form intensity (more than 10MPa) using the method of curing at room temperature in order to solve some economic environmental problems by omitting the steam curing process involved in producing PC (Precast Concrete). Therefore, this study evaluated a rapidly hardening cement containing a high amunt of C3S, which is very responsive in expressing early intensity, and a rapidly hardening type of concrete which uses some hardening accelerator to increase thehydration reaction of $C_3S$. The results of the experiment on concrete using some hardening accelerator are asfollows. In the slump flow experiment for identifying the liquidity and the air test, the desired values were met. The compression strength showed rapid expression response by 12 hours, and met the desired value within 6~9 hours. Its drying shrinkage value and Autogenous shrinkage value were measured as below ($-754.5{\times}10^{-6}$),and satisfied the requirements. In addition, in the Semi-Adiabatic Temperature Test, it was found that the concrete rose to its peak temperature within 24 hours and then its temperature dropped.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.497-503
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• 2018

A strawberry variety 'Arihyang' was derived as an artificial cross between 'Tochiotome' and 'Seolhyang' in 2014. The seedling and line selections were conducted from 2014 to 2015. Preliminary and advanced yield trials of '14-5-5,' which was the final selected line, were conducted from 2015 to 2017. 'Arihyang' is suitable for forced cultivation and has strong plant vigor, uniformly large-sized fruit, and a high yield compared to those of the check variety, 'Seolhyang' and 'Maehyang.' Especially, vitamin C was at a significant level, which was approximately 15% higher than that of 'Seolhyang.' The average number of flowers per first flower cluster was 10.5, which could reduce the labor of thinning fruit. Its fruit has a conical shape, dark red color, and glossy skin. The fruit was of good quality but has recommendations for harvest at the fully ripened stage. 'Arihyang' has intermediate resistant to phytophthora crown rot, but is susceptible to powdery mildew, gray mold, anthracnose, and fusarium wilt. It is reguired to manage major diseases and pests using optimum cultivation techniques and chemical control.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.71-78
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• 2011

Cement treating technique, such as deep mixing method, has been used widely to stabilize the dredged clayey soil for many years. Despite of its effectiveness in treating soil by cement, several efforts have also been made to try to reduce the side effect of the cement that used to stabilize the dredged clay. However, authors considered that more detailed study on the physical and mechanical properties of lean-mixed soil-cement has been required to establish the design procedure to apply the practical problems. Therefore, in this study, the curing time and mixing ratio was used as key parameters to estimate the physical and mechanical properties including long-term behavior. The unconfined strength of lean-mixed soil-cement increase continuously during curing period, 270 days, while increasing rate becomes low in ordinary cement-treated dredged clay. We also concluded that cement-treated dredging clay shows apparent quasi overconsolidation behavior even in low cement proportion. By this study, fundamental approach was carried out for effective reuse of very soft dredged clayey soil both in mechanical and environmental aspect. It can be also expected that this study can propose a basic design data to use the lean-mixed soil cement.