• Fire Science and Engineering
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• v.20 no.4 s.64
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• pp.1-12
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• 2006

In this study, CFD computer simulations by FDS are carried out in order to confirm the performance of the combined operation of both sprinkler system and smoke curtain of 0.54 m depth installed for cooling and blocking the smoke which propagates beneath the sloped ceiling of a stairway corridor of which dimensions are 17.92 m long, 4.00 m wide, and 6.12 m high. It is shown that the response time of sprinklers decreases with fire size and it increases more about 1.1 second in case without smoke curtain than in case with smoke curtain, that the time of smoke transport from the fire source to the stairway outlet decreases considerably with fire size, and that the delay effect of smoke transport is not related to the sprinkler system, whether it is operated or not. This study shows that the combined operation of both sprinkler system and smoke curtain is very effective in smoke cooling, but it is a little for effect on smoke blockage. Although the hazard of skin burn due to radiative heat flux from hot smoke layer is decreased by spray cooling effect, the hazard of smoke suffocation and the weakening of visibility is increased by smoke downdrag and the turbulence of smoke-air mixing due to water spray. These conditions may result in preventing occupants from going out of the stairway during evacuation.

• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.42-46
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• 2006

Rheological properties of the dough added with milk proteins and gums was studied to investigate the possibilities as anti-staling agents. Also, physical properties of the resultant bread baked from the frozen dough after 8 weeks of storage at $-20^{\circ}C$ were examined. The 4 sets of their combinations of milk proteins and gums, $casein-{\kappa}-carrageenan$ (CK), casein-sodium alginate (CA), $whey-{\kappa}-carrageenan$ (WK), and whey-sodium alginate (WA), were added to dough to examine their possible anti-staling effects. Rheological properties of dough were evaluated, and physical properties of resultant bread baked from frozen dough after 8 weeks storage at $-20^{\circ}C$ were examined. Addition of all treatments increased gelatinization temperature and water absorption, and lowered miximum viscosities and extension of doughs, compared to the control. Doughs added with CA and WA showed longer development times than that of the control. Addition of WK and WA resulted in lowest dough extensions. Treated bread showed lower moisture content decrease during storage at $5^{\circ}C$ for 4 days. Breads baked with frozen doughs after 6 weeks storage at $-20^{\circ}C$ showed similar results. Although textural hardness of breads increased with storage at $5^{\circ}C$, CA- and WA-added breads were less affected, showing they effectively retarded staling of breads.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.121-121
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• 2009

자동차는 코너 주행 시 In-corner와 Out-corner 의 바퀴 궤적이 달라지므로, 특별한 장치가 없이 좌우 구동 측의 바퀴가 같은 속도로 회전을 하게 되면 정상적인 주행이 불가능하다. 따라서 정상적인 코너 주행이 가능 하려면, 코너 안쪽 바퀴보다 바깥쪽 바퀴가 더 빨리 회전해야 하며 이러한 회전 차를 보상받지 못할 경우 바깥쪽 바퀴가 끌리는 현상이 발생하는데 이를 방지하기 위해 디퍼렌셜 기어가 필요하다. 현재 디퍼렌셜 기어는 디퍼렌셜 케이스와 링기어를 볼트로 체결하는 조립 공법을 통해 생산되고 있다. 하지만 볼트 체결 공법은 조립을 위한 볼트와 볼트 체결을 위한 플랜지와 볼팅을 위한 홀을 가공하는 공정이 필요하기 때문에 재료비 절감 및 생산 효율 향상에 매우 불리하고 볼트체결을 위한 부분 때문에 불필요한 무게가 증가하게 된다. 따라서 본 연구에서는 이러한 기계적 체결 방식을 레이저 용접 방식으로 대체하여 재료비를 절감하고 무게 저감을 통해 주행성능을 향상시키고자 하였다. 링기어의 소재는 침탄처리강(SCM420H)이며 디퍼렌셜 케이스의 소재는 주철(GCD500)을 사용하고 있다. 주철은 용접시 용접부와 열영향부에서 마르텐사이트 조직과 레데브라이트, 시멘타이트 조직이 생성되며 고탄소 모재의 탄소 확산으로 인한 부분 혼합영역에서 탄소 합금이 생성되어 균열이 발생하는 등 용접성이 매우 좋지 않은 것으로 알려져 있다. 이러한 주철의 난용접성을 해결하는 방법으로는 고탄소 모재 용접시 발생하는 탄소의 확산을 억제하거나 예열이나 후열 처리를 통한 냉각 속도의 제어하는 방법과 오스테나이트 안정화 원소를 첨가한 필러와이어를 사용하여 용접시 마르텐사이트와 시멘타이트의 성장을 방해하는 방법 등이 이용되고 있다. 본 연구에서는 예열처리나 후열처리를 통한 주철의 용접법은 대량 생산을 통한 원가절감을 노리는 자동차 업계의 특성에 비추어 볼 때 비용이나 프로세스 구성 면에서 적용하는 것이 어려울 것이라 판단하여 Ni-base filler metal을 통한 주철의 용접법을 선택하였고 그 결과 실차에 적용하기 위한 비틀림 강성 테스트나 내구 테스트는 통과하였으나 NVH 테스트 결과 볼팅 체결 방식에 비하여 소음이 커지는 문제가 발생하고 링기어의 HAZ부가 고경화 되는 문제가 발생하였다. 때문에 용입깊이를 초기 시제품인 5mm에서 4mm로 변경시켜 입열량 감소 및 용접변형을 줄여 소음 문제를 해결하고자 하였으며 링기어의 침탄층을 1mm 절삭하여 링기어 HAZ부의 고경화 문제를 해결하고자 하였다. 이러한 용접 구조 변경이 용접변형 및 강성과 피로에 미치는 영향력을 알아보고자 용접 및 열처리 상용 소프트웨어인 SYSWELD, 구조해석 상용소프트웨어인 NX_NASTRAN, 피로 해석 상용 소프트웨어인 FEMFAT을 이용하여 시뮬레이션 하였고 실제 구조 변경한 용접 시제품과 비교, 분석하였다.

• FLOWER RESEARCH JOURNAL
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• v.19 no.3
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• pp.144-150
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• 2011

This study was carried out to develop the soil amendment practice by phosphate solubilizing bacteria application in greenhouse chrysanthemum cultivation area with high salt accumulation. The experimental site (ShinWoo Flower, GwangJu) has been cultivated chrysanthemum for 15 years and showed significant salt accumulation. The phosphate solubilizing bacteria, Pseudomonas putida (KSJ11), Acinetobacter calcoaceticus (KSJ3) and Acinetobacter calcoaceticus (WP20) formulated on vermiculite for easy use, were applicated. Each 250L of phosphate solubilizing bacteria was applied for $82m^2$ before planting. Acinetobacter calcoaceticus (KSJ3; WP20) increased the amount of soluble phosphorus in an effective level. Particularly, Acinetobacter calcoaceticus (WP20) increased not only the level of soluble phosphorus but also potassium, calcium and magnesium resulting in the increase of EC in the soil. The level of nematode was also decreased with the non-treated increased. As a result, we suggest that selected phosphate solubilizing bacteria (WP20) could be a useful practice for soil amendment in chrysanthemum plantation soil and provided an opportunity to reduce the use of the fertilizer during the cultivation period.

• Polymer(Korea)
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• v.32 no.5
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• pp.465-469
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• 2008

Hybrid thin films composed of block copolymer(BCP) and $TiO_2$ with various morphologies on the nanoscale were fabricated using self-assembly of block copolymer combined with sol-gel process. The factors governing morphology changes considered in this study are block copolymer composition, selectivity of solvent and the inclusion of an additive. We also investigated the efficiency of photoluminescence for selected films with different morphologies. Micelle or nanowire structure can be derived from the self-assembly of poly (styrene-block-4-vinyl pyridine) (PS-b-P4VP) depending on the relative selectivity of the solvent for the two blocks, and the titanium tetraisopropoxide ($Ti{OCH (CH_3)_2}_4$, TTIP) is coordinated with nitrogen in P4VP block. Addition of a third component 3-pentadecylphenol into the BCP/sol-gel mixture solution induces morphology change as a result of the change of relative volume fraction of the BCP. We confirmed that the efficiency of $TiO_2$ fluorescence changes for films depending on morphologies.

• Food Science and Preservation
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• v.14 no.2
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• pp.154-159
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• 2007

In efforts to use pine needle extract as a substitute for sugar, fermented pine needle extract syrup was added to the wheat flour nea in the manufacture of white bread The extract was added to levels of 8.3%, 11% and 18% of total weight based on the Brix degree of the dough The cohesion of each dough was checked, and the physical properties and storage stabilities of the baked breads were analyzed during storage at mom temperature. Analysis of the cohesion of each dough by farinogram showed that dough with pine needle extract was better than dough with sugar, in terms of both stability and durability of mixing. The pH of dough with syrup was steady during storage at pH 5.4 5.8, which is favorable for yeast activity. The dough with syrup also showed low firmness and good extensibility, both of which would favorably affect gas retention on fermentation. Increases in syrup addition resulted in higher product volumes. Bread with syrup was slow to increase in hardness during storage, suggesting that higher syrup concentrations inhibited development of staleness. The addition of syrup also inhibited the growth of aerobic bacteria and mold on the bread surface. The addition of syn did not cause any negative effect. The use of pine none extract syrup may thus contribute to improvements the physical properties, the storage stability, and the hygienic quality of bread.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.33-42
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• 2021

Modern aircraft fighters improve the maneuverability and performance with the RSS (Relaxed Static Stability) concept and therefore these aircrafts are susceptible to abrupt pitch-up in the transonic and moderate Angle-of-Attack (AoA) flight region where the shock wave is formed and the mean aerodynamic center is moved forward during deceleration. Also, the modeling of the aircraft flying in this flight region is very difficult due to complex flow filed and unpredictable dynamic characteristics and the model-based control design technique does not fully cover this problem. In this paper, we analyzed the performance of the TPMC (Transonic Pitching Moment Compensation) control based on the model-based IDI (Incremental Dynamic Inversion) and the Hybrid IDI based on the model and sensor based IDI during the SDT (Slow Down Turn) in transonic region. As the result, the Hybrid IDI had quicker response and the same maximum g suppression performance and provided the predictable flying qualities compared to the TPMC control. The Hybrid IDI improved the performance of the Over-G protection controller in the transonic and moderate AoA region

• Composites Research
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• v.32 no.2
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• pp.90-95
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• 2019

Sloshing impact loads on liquefied natural gas (LNG) carr iers are the main issue of damage to the insulation system in LNG cargo containment system (LNG CCS). The damage to the insulation system would be fatal in maintaining a temperature-savings environment in LNG CCS. The typical method is to enhance the insulation materials that can maintain a constant cryogenic temperature. Insulation materials consist of polyurethane foam and plywood, an adhesive for bonding these two materials. This study intends to improve the absorption energy of the material when the impact load is applied by creating a glass bubble/epoxy composite resin as part of the insulation. The experimental scenarios consider the effect of temperature ($20^{\circ}C$, $-163^{\circ}C$), glass bubble weight fraction in epoxy resin through free fall experiments. Experiments have shown that if the glass bubble additive reaches 20 wt.%, the cryogenic absorption energy is a maximum performance and that 0 wt.% has a maximum ambient absorption energy. However, the agglomeration has been occurred due to deterioration of the stirring performance if weight fraction was 20 wt.% and the result of 0 wt.% have been revealed that ambient absorption energy is significantly lower.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.252-258
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• 2018

A larger energy consumption and concentration of population induced green house gas glowing and heat island effect in the urban space. Roof green system was a effect method to reduce green house gas and heat concentration in the city. Therefore, construction of this system was increasing. Most of lightweight soil used in roof green system was perlite, but this caused dust and skin disease. So it needed to develop another new lightweight soli for roof green system. Meanwhile, a thermoelectric power plant generated bottom ash as a by-product. According to previous research, bottom ash could be used for artificial lightweight soil with 60 wt% of mixing rate. But this study was proceed to develop a artificial lightweight soil using bottom ash with higher mixing rate by 65 wt% and different organic ingredients. First, physical and chemical properties of bottom ash was investigated. Then test according to landscaping design standard was proceeded for various artificial lightweight soil mix types using bottom ash, bark, compost and coco peat. As a result, the artificial lightweight soil with 65% of bottom ash, 30% of bark and 5% of compost was suitable for low and middle range of soil standard.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.91-91
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• 2019

전북 완주군 농가에서 2017년 12월에 재배한 '시베리아'와 '메두사' 품종을 1시간 이내에 국립원예특작과학원 실험실로 이동하였다. 알약(SmartFreshTM, AgroFresh Inc., USA)형태의 1-MCP를 1.875g/3.55m3 기준으로 정량하여 Activator Kit(SmartFreshTM, AgroFresh Inc., USA)에 넣어 마개를 닫고 몇 번 흔들어주어 녹인 후 1.5 ppm이 되도록 처리하였으며 3시간 훈증 후 30분 환기하였다. 훈증처리 후 절화 백합은 유공 필름 슬리브를 이용하여 포장한 후 골판지상자에 넣어 모의 수출환경에서 수송방식은 건식(건조처리)상태로 $4^{\circ}C$ 저장고에 암상태로 저장하면서 무처리를 대조로 에틸렌 노출 조건 조성을 위하여 후레쉬라이프(탑프레쉬) 5g 봉지를 상자내부 5개, 상자외부 저장고 내에 10개로 총 15개의 에틸렌 발생제 처리를 하였다. 백합 절화 신선도 유지기간 연장을 위한 선도유지제 전처리 효과는 1.5 ppm 1-MCP 3시간 훈증처리에 의해 잎의 황화현상을 지연시키는 효과가 있었다. 전체적으로 판정한 절화수명은 '시베리아'는 무처리 9.0일, 1-MCP 훈증 9.0일, 에틸렌 발생제 8.3일, 1-MCP 훈증+에틸렌 발생제 9.5일이었으며 '메두사'는 무처리 6.5일, 1-MCP 훈증 7.5일, 에틸렌 발생제 5.7일, 1-MCP 훈증+에틸렌 발생제 8.5일로 나타났다. 에틸렌에 노출은 꽃의 빠른 노화를 야기하여 절화수명을 단축 시켰으며 이상개화를 보이는 꽃도 있어 상품성이 크게 떨어졌다. 1-MCP에 의해 잎의 황화 억제에 효과적이었으며 저장 중 에틸렌 발생제를 동시에 처리하였을 때 품질유지 효과가 더 크게 나타났으며 '메두사' 품종에서는 만개시 화색도 더 진하게 나타났다. 따라서, 저온저장이나 선적시 에틸렌 발생이 많은 품목과 혼합하게 될 것이 예상될 경우에 품질유지를 위해 1-MCP 훈증처리를 하면 효과적일 것으로 사료된다.