• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.2
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• pp.157-169
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• 2007

This study aimed to quantify the deterioration of tunnel structural members such as concrete lining and shotcrete lining after a tunnel fire accident by measuring their mechanical properties between $300^{\circ}C$ and $1,000^{\circ}C$. From the experiments, it was revealed that the critical temperature where mechanical properties start to decrease linearly was approximately $300^{\circ}C$. In addition, the other critical temperature where macro-cracks are induced in specimens was around $600^{\circ}C$. From a series of regression analysis, the optimum regression function with correlation coefficients over 0.99 for mechanical properties at different temperature levels was obtained as the Boltzmann function. Finally, a schematic diagram to estimate temperature distribution inside structural members as well as their mechanical properties at corresponding temperature levels quantitatively was newly proposed for RABT and RWS fire scenarios.

• Land and Housing Review
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• v.7 no.1
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• pp.53-63
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• 2016

This paper contains structural analysis and design regarding how three types of green roof load affect roof slab design of LH housing and facilities. Based on the Structural analysis, an appropriate Roof slab rebar guideline and roof slab thickness have been set up for the green roof load which takes effect on structural design of roof slab. Result of structural analysis and design has been made as follows. Roof slabs can arrange the slab rebar(D10) within the 200~250mm disregarding the types of the green roof load and the pattern of green roof load; also, slab thickness can be designed within 150mm. Moreover, even if the concrete design strength of roof slab changes to 24, 27, and 30MPa, D10 rebar can still be arranged within 200~250mm, and 150mm for slab thickness. Two-way slab of commercial building was appeared to be arranged by slab rebar(D10) within 200mm and 150mm for slab thickness disregarding the soil type or the soil thickness of green roof.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.522-526
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• 2007

Structural features and electrochemical performances of cokes pyrolized from oxidized cokes were examined, and compared with KOH-activated coke. Needle cokes ($d_{002}=3.5{\AA} $), having a graphene layer structure, were changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an $NaCLO_3$/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized coke was expanded to $6.9{\AA} $ with increasing oxygen content. After heating at $200^{\circ}C$, the oxidized coke was pyrolized to the graphene layer structure with inter-layer distance of $3.6{\AA} $. However, the change of the inter-layer distance of the needle coke was not observed in the KOH activation process. On the other hand, an intercalation of electrolyte ions into the pyrolized coke, observed at first charge, occurred at 1.0 V, in which the value was lower than that of KOH-activation coke. The cell capacitor using pyrolized coke exhibited a lower internal resistance of $0.57{\Omega}$ in 1 kHz, and a larger capacitance per weight and volume of 30.3 F/g and 26.9 F/ml at the two-electrode system in the potential range 0~2.5 V than those of the cell capacitor using KOH-activation of coke. This better electrochemical performance may be associated with structure defects in the graphene layer derived from the process of the inter-layer expansion and shrinkage.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.405-413
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• 1975

The objective of this study was to examine the effect of testosterone on the spermatogenesis. Testosterone propionate was administered in 20 mg dose to male rat with 10 days interval for 50 days and the treated rat was compared with normal one in their testis weight and histological changes. The results were as follows: 1. The longer treatment gave the more decreased testis weight. Treated rat for more than 20 days was significantly different from the untreated one. 2. Diameter of seminiferous tubule was significantly reduced in 40 and 50 days treatments. 3. The ratio of disrupted spermatogenesis on seminiferous tubles was significantly increased from 20 days treatment. 4. On volumetric proportion of testicular structure, spermatozoa and spermatid were significantly reduced from 20 and 30 days treatments respectively. Other components in testis were not changed. 5. The administration of testosterone in over dose damages spermatozoa and spermatid more than other components in testis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.19-26
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• 1993

In this study rats in fasting or fed protein free restricted diet including only fat showed much lowered level of serum cholesterol and triglyceride accompanied by utmost weight loss and high level of blood urea nitrogen indicated the tissue degradation, especially in liver with signs of damage or necrosis of hepatic parenchymal cell leading to elevated glutamic pyruvate transaminase value and to death. Rats fed only perilla oil in starvation or as fat source in normal diet dropped down the level of serum cholesterol and triglyceride compared to beef tallow fed rat. But with evidence of glutamic pyruvate transaminase values which was significantly elevated long term ingestion of perilla oil is likely to cause the lesion or any damage of hepatic function.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.179-184
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• 2017

The cage of a tapered roller bearing keeps the gap between the rollers, which prevents friction, wear and suppresses heating. The material of the cage is changing from metal to plastic for lightening the weight. If the cage is severely deformed due to resonance, the roller may not be able to roll and even get off the cage. In this paper, the dynamic characteristics of the cage is analyzed according to the cage material. Under the assumption that a train runs at the highest speed, frequency harmonics of that speed is calculated, and the comparative analysis is carried out in order to select the optimum thickness of the cage, which is easy to change among the cage design variables for avoiding the resonance.

• Proceedings of the Korean Society of Community Living Science Conference
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• 2009.09a
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• pp.89-89
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• 2009

순무(Brassica rapa L., Brassica campestris L.)는 십자화과에 속하는 채소로 무의 일종이다. 모양은 팽이와 유사하고 껍질은 적자색을 띄고 있다. 이를 원료로 한 연구로 피클, 젖산발효, 식이섬유소의 함량, 성분분석에 관한 연구 등이 보고되어 있다. 본 연구에서는 순무를 활용한 농가형 음료 및 식품 소재 개발의 일환으로 자당 첨가량과 발효온도를 달리하여 순무 발효액을 제조하고 이화학적 특성을 검토하였다. 순무는 강화군 농가에서 직접 구입하였다. 순무를 $4{\times}5{\times}1cm$의 크기로 세절하고 중량대비 40%, 60%, 80%, 100%의 자당을 첨가한 다음 $24^{\circ}C$에서 15일간 발효하였다. 또한 발효온도에 따른 변화는 60%의 자당을 첨가하여 $18^{\circ}C,\;24^{\circ}C,\;30^{\circ}C$에서 21일간 발효하였다. 시료는 3일 간격으로 채취하여 수율, 당도($^{\circ}Brix$), 산도(acetic acid, %), pH를 조사하였다. 자당 첨가량이 추출 수율에 미치는 영향은 40%, 60%, 80%, 100% 순으로 각각 39.14%, 55.38%, 53.56%, 55.72%로 40%를 첨가한 군을 제외하고 차이가 없었다. 당도와 pH는 자당 첨가량이 높을수록 증가하였고 총 산도는 각각 0.415, 0.446, 0.242, 0.194 (acetic acid, %)로 나왔다. 발효온도에 따른 당도와 pH의 변화는 시간이 경과할수록 감소하였으나 산도는 발효 15일 이후에는 $30^{\circ}C$가 $24^{\circ}C$보다 점차 높아졌다. 총산도의 변화는 $24^{\circ}C$와 $30^{\circ}C$에서 차이가 없었다. 본 실험의 결과에서 볼 때 순무발효액을 추출하기 위한 가공조건은 60~80%의 자당을 첨가하여 $24^{\circ}C$에서 15일간 발효하는 것이 적당한 것으로 사료된다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1059-1068
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• 1990

The minimum weight design for the simply-supported eccentrically stiffened plates subjected to combined loads is studied according to the stiffening configuration. The optimal programming is accomplished by formulating the design requirements in terms of a mathematical programming problem, and by using the gradient projection algorithm. The Huber type equilibrium equation is used as the governing equation for the overall buckling. The overall buckling of stiffened plates and the local buckling of the unstiffened plate between stiffeners and the stiffeners themselves are used as behavior constraints. Results of design examples for the orthogonally stiffening case compared with those of the other study support that the present study is feasible. Design examples for the symmetrically oblique stiffening case are presented and the results indicate that a significant improvement in design efficiency may be achieved through symmetrically oblique stiffening compared to the orthogonal stiffening under the combined loading condition.

• Spatial Information Research
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• v.19 no.1
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• pp.1-11
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• 2011

Recently urban area has suffered from frequent flood event by local heavy rain. This study performed flood tests for the Jungnang river using HEC-RAS model. Based on 1m LiDAR data, river geometry data were produced using HEC-GeoRAS. For 100-year frequency flood, 200-year frequency flood, and PMF, flooding areas were estimated. Ten sub-zones of the entire flooding area were identified based on the nearest refugees and used to analyze evacuation paths to the refugees. The results showed that approximately 70% of flooded area were residential, commercial, and transportation areas so that much loss of life and property could be possible. Path analysis showed that the shortest path distances to refugees were about 1000m average. Evacuation warning given at a proper period could minimize loss of life and property. This study provides the guideline for flood evacuation plan in urban area.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.99-99
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• 2017

국내 콩의 소비량은 계속적으로 증가하고 있다. 재배 면적은 1995년 10,000ha에서 2013년 8,000ha까지 계속적으로 감소하였으며, 수입은 2009년 644.9백만 달러에서 2013년 883.3백만 달러까지 계속적인 증가 추세에 있다. 건조는 품질 손상을 최소화 및 수분을 제거하는 공정이다. 모든 곡물에는 건조 조건에 따라서 품질이 크게 변화하며, 건조 과정을 해석하여 해당 곡물의 적정 건조 조건을 구명하여 품질을 유지하는 위해서는 중요하다(Keum, 등 1977). 얇은 두께의 곡물층을 단층으로 하여 건조속도 및 건조공기의 조건을 나타내는 것을 박층(Thin layer)건조모델이라 한다. 박층건조모델을 계속적으로 쌓은 모델을 후층(Deep layer)모델이라 하며, 건조기 개발 및 건조조건 구명에 가장 기본이 된다(Basunia and Abe, 1998). 그러나 해외에서 만들어진 콩 박층건조 모델은 국내의 검은콩과 물성이 상이하여 건조조건이 다르게 설정 되어야 한다. 따라서, 본 연구목적은 건조온도 2수준, 상대습도 3수준에 대하여 검은 콩의 건조속도 측정하고, 곡물건조방정식으로 많이 이용되고 있는 4개의 건조방정식에 대하여 모델 적합성을 검정하여 검은콩 건조에 적합한 박층건조모델 결정하는데 있다. 공시재료는 2015년 강원도지역에서 생산된 검은콩을 실험에 사용하였으며, 초기 함수율은 14.7%,w.b.였다. 박층 건조공기 조성은 공기조화장치(MTH4100, SANYO, UK)를 사용하여 조성하였으며, 송풍기에 의해 공기충만실을 통과하여 건조 층을 통과하도록 구성하였다. 목표 평형함수율에 도달하면 실험을 종료하였다. 건조 층의 초기중량 및 경시적 변화는 전자저울(GF-4000, AND, Japan)을 이용하여 10분 간격 측정하여 저장하였다. 적정 박층건조모델을 결정하기 위하여 기존의 곡물건조방정식 중 널리 사용되고 있는 4개(Lewis, 1921; Page, 1949; Thompson, 1967; Moisture diffusion, 1975)의 건조모델을 이용하여 비교 검증하였다. 건조 초기 2시간 까지는 급격히 감소하다가 건조속도에 영향을 미치는 반건조시간(MR=0.5) 이후에는 완만하게 건조되는 것으로 나타났고 건조조건으로 건조온도 및 상대습도 모두의 영향이 미치는 것으로 나타났다. 4가지 건조 모델과 비교한 결과 Thompson 모델이 전체 건조 영역에서 비교적 잘 일치하였다.