• The Science & Technology
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• v.11 no.10 s.113
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• pp.10-11
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• 1978

국립천문대 (대장 민영기 박사)는 지난 9월 29일 소백산 연화 제 2봉에 천체 관측설비를 5년만에 준공한 바 있다. 경주 첨성대를 본뜬 첨성관에 20cm 태양망원경, 60cm 반사망원경 돔, 광학험기계들, Mini Computer를 갖춘 각 연구실을 마련한 이 관측소에서 무엇이 이루어 질것인가? 민영기 박사에게 전망을 들어본다.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.368-373
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• 2009

A human tissue mimicking phantom is constructed to assess the performance of a medical ultrasound elasticity imaging system. In a human body, the tumor or cancer is stiffer than its surrounding normal tissue. A technique fur imaging the elasticity of such a tissue is referred to as elastography. Homogeneous elasticity phantoms with differing Young's moduli are constructed using a plastic hardener and softener to simulate the mechanical characteristics of a diseased human tissue. The Young's modulus of the fabricated homogeneous phantom materials were measured from 11.1 to 79.6 kPa depending on the mixing ratio of the amount of the hardener to that of the softener. An ultrasound lesion mimicking phantom was made of these materials, and ultrasound elasticity imaging was performed on it. It is confirmed in this paper that the fabricated plastic-based elasticity phantom is useful in representing the elastic characteristics of a human tissue.

• Elastomers and Composites
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• v.11 no.2
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• pp.122-129
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• 1976

합성(合成)고무는 일반적(一般的)으로 천연(天然)고무에 비(比)하여 roll 가황성(加工性)이나 압출특성(押出特性)이 불량(不良)하다. 그러나 적당(適當)한 배합제(配合劑)의 선택(選擇)이나 가공조작(加工操作), 또는 천연(天然)고무와의 blend 등에 따라 이러한 문제(間題)들은 개선(改善)될 수 있다. 압출특성(押出特性)은 천연(天然)고무나 SBR 공(共)히 Polymer의 소연(素練)의 정도(程度), 보강제(補强劑)나 충전제(充塡劑) 기타(其他) 연화제(軟化劑)의 첨가량(添加量)등에 크게 영향(影響)을 받게 되며 그 영향(影響)은 천연(天然)고무는 소연(素練)의 정도(程度)에 SBR은 보강제(補强劑)의 첨가량(添加量)에 크게 좌우(左右)된다.

• Elastomers and Composites
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• v.42 no.3
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• pp.168-176
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• 2007

When the rubber vulcanizates reinforced with carbon black or silica are subjected to cyclic loading from its virgin state, the stress required on reloading is less than that on the initial loading. This stress softening phenomenon is referred to as the Mullins effect. The strain energy function of rubber vulcanizates was investigated using theory of pseudo-elasticity incorporated damage parameter that Ogden and Roxburgh have proposed to describe the damage-induced stress softening effect in rubber-like solids. The quasi-static cyclic loading test was performed using the NR-SBR vulcanizates reinforced with carbon black, and then the effect of a damage parameter to stress-strain curve in reloading and subsequent reloading paths was studied. The strain energy function of the rubber vulcanizates with a different filler content was also evaluated.

• Journal of Sericultural and Entomological Science
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• v.4
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• pp.63-68
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• 1965

This treatise was carried out to study the hereditary phenomenon of silk lousiness and the interaction of genes related with silk lousiness. It was also studied how to improve the silk lousiness of general raw silk by refining process because the selective process was found as unsatisfactory method. The conclusions reached were as follows. A. Conclusions related with genetic problem. 1. The decreased effects of the lousiness were 11 % in the F$_1$ hybrids. 2. Lousiness was considered to inherit as the incomplete dominance. 3. The effects of the lousiness gene were additive, and the lousiness of raw silk might be influenced by more than two genes. 4. The quantitative characters of cocoons were not genetically correlated with the occurrence of lousiness. 5. Lousiness could not be said to occur more in the heavy-cocoon strains. 6. The microscopic lousiness test of this paper showed the same result of the international exforiation test. B. Conclusions related with lousiness improvement. 1. Raw silk was able to be refined by the employment of 0.2% cationic softener solution for 30 minutes at 95$^{\circ}C$, supressing the occurrence of lousiness. 2. Anionic chemical softener was not available for silk refining process. 3. The above cationic softener refining prosess did not cause any physical defect for the silk fiber. 4. Soap refining process caused silk lousiness easily.

• Elastomers and Composites
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• v.44 no.1
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• pp.69-75
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• 2009

Asphalt sealants for the crack repair of asphalt concrete road were prepared using waste lubricant oil in this work. The waste lubricant oil was compounded with asphalt(AP-5), SBS triblock copolymer, a tackifying agent(petroleum resin), and antioxidants. Cone penetration, softening point, ductility, elongation by tensile adhesion, and resilience of asphalt sealant compounds were measured. Cone penetration of asphalt sealant compounds increased with the increase of waste lubricant oil content while their softening point, ductility, and resilience decreased. By the addition of talc as an extender, softening point and resilience of asphalt sealants increased, but cone penetration, ductility, and elongation by tensile adhesion of those decreased with the proportion of talc content. The most economic asphalt sealant which could pass an ASTM specification could be manufactured by the big decrement of petroleum resin content.

• Explosives and Blasting
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• v.18 no.3
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• pp.7-13
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• 2000

인류의 역사에서 "제2의불"의 발견이라고 하는 것이 화약의 발명이다. 이 화약은 활용성과 기능성 및 안전성에 따라 흑색화약으로부터 에멀젼(Emulsion)폭약에 이르기까지, 그리고 공업 뇌관에서부터 비전기식 뇌관에 이르기까지 부단히 개발 발전되어 왔고, 그 응용범위도 다양해졌다. 또한 "불의 예술"이라고도 하고 "밤하늘의 서사시"라고도 일컬어지는 연화를 사용한 불꽃놀이가 각종 기념행사 때 볼거리로 모든 이를 즐겁게 하여준다. 이에 화약류의 올바른 이해와 사용을 위해 연화를 포함한 화약류의 역사를 살펴보고 화약기술의 발전방향을 전망해 보고자 한다.를 살펴보고 화약기술의 발전방향을 전망해 보고자 한다.

• The tire
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• s.65
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• pp.3-9
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• 1976

가유 고무에 대변형의 반복왜를 외부자극으로서 부여하면 초기에는 대폭의 응력의 변화현상이 보여져 서서히 일정응력치에 접근하여 파단에 이른다. 이 응력의 변화현상과 피로수명(파단하기까지의 회수)이 여하한 기계적 화학적 인자의 영향을 받는가를 천연고무의 순고무 가유물로 검토했다. 그 결과 실온으로 고무에 반복신장피로를 부여하면 가교구조, 망목밀도 및 신장률이 응력변화의 대소, 피로수명의 증감에 영향을 주었다. 고온으로 고무에 반복신장피로를 주면 열산화에 의하여 어느 온도로부터 현저한 응력연화(화학응력연화) 현상이 보였다. 연이나 고무에 열화방지제를 첨가하면 고온에 있어서의 산화반응이 억제되기 때문에 무첨가의 경우와 달라서 파단이나 현저한 응력연화가 일어나지 않았다. 피로수명(F)와 파괴신장(εb),반복신장률(ε)사이에 F=A(εb-ε)n 의 관계가 성립함이 인정되었다. An은 고유의 파라메에터어이며 천연고무의 순고무가유물로서 n은 4.0~4.5의 거의 일정치를 표시했다.

• Elastomers and Composites
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• v.39 no.1
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• pp.61-70
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• 2004

This work is about the development or asphalt sealant using the waste edible oil. Asphalt sealant has been used for crack filler and bridge deck joint sealer Several plasticizers such as aromatic or paraffin process oils, DOP, Bunker C fuel oil, and waste edible oil were compounded with the basic components such as asphalt(AP-5), a thermoplastic elastomer(SBS triblock copolymer), a tackifying agent(petroleum resin), and stabilizers. Penetration, softening point, ductility, and elongation by tensile adhesion of those asphalt sealant compounds were measured. Their properties were changed largely depending on both the type and content of plasticizers. Waste edible oil and DOP were the best plasticizers for the low temperature tensile adhesion characteristics. Penetration and elongation by tensile adhesion of asphalt sealant compounds increased with the increase of waste edible oil content and decreased with the increase of talc content. The manufacture of asphalt sealant with low penetration and excellent low temperature tensile adhesion was possible by the recipe optimization.

• Food Science and Preservation
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• v.14 no.3
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• pp.288-293
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• 2007

Intermediate moisture-apple snail products were prepared by adding glycerol, sorbitol, kiwi, or pineapple(2% or 5% w/w), as tenderizers, and by drying at $4^{\circ}C$ for 24 hr. The effects of the tenderizers on textural and sensory properties of the apple snail products at intermediate moisture levels were investigated. Moisture content and water activity of the products were ranged from 26.25 to 34.48% and from 0.83 to 0.87, respectively. The addition of glycerol significantly lowered water activity of apple snail samples compared to control prepared without tenderizers. On the other hand, significant increases in moisture content and water activity were observed in apple snail samples treated with kiwi or pineapple(p<0.05). All apple snail samples treated with tenderizers showed a lower shear force than did the control. Apple snail samples treated with 5%(v/v) glycerol showed a higher equilibrium moisture content than did the other samples. SDS-PAGE indicated that proteolytic enzymes in kiwi and pineapple clearly changed the structure of the myosin heavy chain and actin filaments of myofibrillar protein in apple snail samples. Intermediate moisture apple snail samples treated with tenderizers showed significantly improved overall sensory characteristics. The highest overall acceptability was obtained from apple snail samples treated with 5% pineapple, while the lowest overall acceptability was noted in the control sample. This study demonstrates that an acceptable apple snail, with intermediate moisture content, may be produced by using tenderizers at appropriate concentrations.