• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권5호
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• pp.380-390
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• 2004

Bone healing plays an important role in orthognathic and craniofacial surgery. Bone tissue repair and regeneration are regulated by an array of growth and morphogenetic factors. Bone formation and remodeling require continuous generation of osteoprogenitor cells from bone marrow stromal cells, which generate and respond to a variety of growth factors with putative roles in hematopoiesis and mesenchymal differentiation. In this study, the efficacy of a single application of hepatocyte growth factor to promote bone regeneration in 5-mm experimental calvarial defects of adult male rats was assessed histologically and immunohistochemically. The result of the experimental site were compared with those of the contralateral contral side. None of the control and experimental bone defects demonstrated complete bone closure. Bone regeneration was found close th the margine and central part of the defects. At 1, 2 weeks, there were found much significant cellural mitotic activity and many inflammatory cells and osteoblasts on the experimental site than control site. At 4, 6 weeks, new bone apposition was founded in both site but, more apposition was seen at experimental site. At 8, 12 weeks, also, some differences was found that more apposition of new bone and collagen fiber was seen on experimental site. Our results have some possibility that HGF do a early positive role to repair the bone defect. More study will be needed.

• 한국자원식물학회지
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• 제22권4호
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• pp.293-298
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• 2009

종자 수확 후 버려지는 산업용 대마를 이용한 목질 펠릿제조 가능성과 제조된 펠릿의 특성을 살펴보았다. 산업용 대마의 성분 분석 결과 활엽수와 비슷한 리그닌 함량과 당구성을 보였으며, 회분 분석 결과 무기물 함량이 0.5% 정도이어서 연료로 사용할 경우 재의 생산량은 크지 않을 것이다. 원소 분석 결과 대기 오염을 유발할 수 있는 질소와 황 함량을 분석한 결과, 황 성분은 전혀 포함하지 않고 있으며, 약간의 질소 성분을 포함하고 있는데 이는 현사시나무와 비슷한 수준이었다. 고위발열량 측정 결과 대마 목부는 현사시나무보다 다소 낮은 값을 나타내었다. 바이오매스 생산량이 큰 대마 목부를 이용하여 제조한 펠릿은 활엽수로 제조한 펠릿과 비슷한 화학적 성질과 발열 특성을 가질 것으로 기대되어 고체연료로서의 이용이 가능할 것으로 사료되었다.

• 대한의생명과학회지
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• 제12권1호
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• pp.9-16
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• 2006

We investigated the effects of 835-MHz electromagnetic field (EMF), one of the most popular communication frequency band in Korean code-division multiple-access (CDMA) mobile phone system, on cellular signal transduction. For this, we examined the change of intracellular calcium $([Ca^{2+}]_i)$, reactive oxygen species (ROS) and F-actin polymerization after exposure to 835-MHz EMF followed by the treatment of agonists in Rat-2 fibroblast cells. Culture cells were pretreated with serum-tree medium and concomitantly exposed to 835-MHz at specific absorption rate (SAR) of 4.0 W/kg for 24 hr in a specialized designed apparatus based on Transverse Electro Magnetics (TEM) wave theory. Intracellular $Ca^{2+}$ responses to lysophosphatidic acid (LPA) and epidermal growth factor (EGF) in Rat-2 fibroblast after exposure to 835-MHz EMF were shown to be similar pattern as observed in normal cultured cells. However, the LPA-induced calcium spiking was slightly delayed to 7 sec and sustained thereafter to a little higher ground level under 835-MHz EMF radiation compared to unexposed cells. ROS production level by LPA in the exposed cells was not different from that in control. Furthermore, LPA induced the production of stress fibers with no significant difference in the exposed and unexposed cells. These results suggest that mobile phone radiation (835-MHz, SAR 4.0 W/kg) may not be directly related to signal transduction in Rat-2 fibroblasts except the slight effect of calcium spiking in LPA-induced cells but remain to be further elucidated for possible indirect intervention.

• 한국식품과학회지
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• 제32권4호
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• pp.908-913
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• 2000

사과쥬스 제조 후 대부분 폐기 처분되고 있는 사과박의 이용성을 증대하기 위해 사과박의 유용성분을 분석하고 사과박 추출물의 항산화 활성을 조사하였다. 사과박의 총플라보노이드 함량은 458 mg%, 총페놀 함량은 1048 mg%, 비타민 C함량은 19.8 mg%로 나타났으며 사과박의 식이섬유 함량은 총식이섬유 55.56%, 수용성 식이섬유 14.20%, 불용성 식이섬유41.36%로 나타났다. 사과박의 phenolic acid는 protocatechuic acid가 3.51 mg%로 가장 높은 함량을 나타내었으며 사과박의 flavonoid를 HPLC로 분석하였을때 phloridzin과 quercetin-3-glucoside가 확인되었으며 각각의 함량은 48.87 mg%, 16.22 mg%로 나타났다. 사과박의 각 분획별 항산화능 시험에서 지용성 모델계에서 BHA와 ${\alpha}-tocopherol$보다는 낮지만 ethyl acetate 획분이 높은 항산화능을 나타내었을 뿐만 아니라 쥐 간조직을 기질로한 과산화지질 생성억제 시험에서도 ethyl acetate 획분이 가장 낮은 값을 나타내었다.

• 폴리머
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• 제25권6호
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• pp.866-875
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• 2001

본 연구에서는 고온 산화분위기 하에서 탄소/탄소 복합재료의 열적 향상을 위해 사용된 tetraethylorthosilicate(TEOS)의 첨가량에 따른 복합재료의 kinetic parameter에 기초한 열분해 메카니즘 및 열안정성을 열중량분석기(TGA)를 사용하여 고찰하였다 TEOS를 함유한 탄소/탄소 복합재료의 kinetic parameter, 즉 열분해 활성화 에너지 ($E_d$), 반응차수(n), 지수앞 인자 (A)는 각각 136 kJ/mol, 0차, 및 2.3$\times$$10^9s^{-1}$을 나타내었으며, 특히 IPDT 및 $E_d$로부터 살펴본 복합재료의 열안정성은 탄소/탄소 복합재료에 TEOS가 첨가되면 크게 향상되었는데, 이는 산소에 대한 산화방지막, 즉 $SiO_2$의 형성으로 인한 복합재료 표면에서의 카본 활성종에 산소의 침투를 방해하여 TEOS를 함유한 복합재료가 이를 함유하지 않은 것에 비하여 표면 산화 속도가 감소되어 열안정성이 증가하였다고 사료된다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.561-569
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• 2002

Laser has been called a "Quantum Machine" because of its mechanism of generation since the development on July 7,1960.by T.H.Maiman. We can now use this machine as a tool for manufacturing in industries. At present, 45kW CO2 laser, 10kW Nd:YAG laser, 6kW LD pumped YAG laser and 4kW direct diode laser facilities are available for welding a heavy steel plate of 40mm in thickness and for cutting metals at high speed of 140m/min. Laser Materials Processing is no longer a scientific curiosity but a modern tool in industries. Lasers in manufacturing sector are currently used in welding, cutting, drilling, cladding, marking, cleaning, micro-machining and forming. Recently, high power laser diode, 10kW LD pumped YAG laser, 700W fiber laser and excimer laser have been developed in the industrialized countries. As a result of large numbers of research and developments, the modem laser materials processing has been realized and used in all kinds of industries now. In the present paper, metallurgical studies on laser materials processing such as porosity formation, hot cracking and the joint performances of steels and aluminum alloys and dissimilar joint are discussed after the introduction of laser facilities and laser applications in industries such as automotive industry, electronics industry, and steel making industry. The wave towards the use of laser materials processing and its penetration into many industries has started in many countries now. Especially, development of high power/quality diode laser will be accelerate the introduction of this magnificent tool, because of the high efficiency of about 50%, long life time and compact.

• 마이크로전자및패키징학회지
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• 제6권3호
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• pp.65-71
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• 1999

광 패키징에서 광섬유와 광전자소자를 정확히 정렬하기 위한 V-groove의 치수 정밀도에 미치는 마스크 재료와 에칭용액의 영향을 연구하였다. PECVD nitride, LPCVD nitride, thermal oxide($SiO_2$)를 마스크재료로 사용하였고 실리콘을 이방성에칭하는 용액으로 KOH(40wt%)용액과 KOH(40wt%)용액에 IPA를 첨가한 용액을 이용하였다. 마스크재료로는 LPCVD nitride가 가장 좋은 선택적에칭특성을 나타내었으며 사용된 마스크재료 중 thermal oxide가 가장 빠른 속도로 에칭되었다. V-groove의 크기 증가는 마스크충 아래로의 undercutting에 의해 생겼는데 이는 주로 (111)면으로의 에칭 때문이었다. KOH(40wt%)용액에서 (111)면의 에칭속도는 0.034 - 0.037 $\mu\textrm{m}$/min로 마스크재료에 관계없이 거의 일정하였다. IPA를 KOH(40wt%)용액에 첨가하면 (100)면과 (111)면의 에칭속도는 모두 감소하지만 (111)면에 대한 (100)면의 에칭속도비는 증가하였다. 그러므로 이런 용액에서 (111)면으로의 에칭에 의한 undercutting현상은 줄어들었으며 V-groove의 크기를 더 정확하게 조절할 수 있었다.

• Composites Research
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• 제29권5호
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• pp.262-268
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• 2016

본 연구에서는 피치계 탄소섬유기반 탄소종이에 바인더 피치와 PAN계 미분쇄 탄소섬유를 첨가하여 저온탄화를 통해 재함침된 탄소종이를 제작하였으며, 미분쇄 탄소섬유의 첨가가 탄소종이의 기계적 및 전기적 특성과 열전도도에 미치는 영향을 알아보았다. 실험 결과, 인장강도는 미분쇄 탄소섬유 함량 10 wt.%부터 20 wt.%까지 첨가하였을 때 크게 증가하였다. 또한, 미분쇄 탄소섬유 함량이 증가함에 따라 계면접촉저항은 감소하였으며, 전기전도도 및 열전도도는 증가하였다. 이러한 결과는 미분쇄된 탄소섬유의 첨가가 탄소종이의 밀도를 증가시킴에 따라 전기적 및 열적 전달 경로가 형성되었기 때문이라고 판단된다.

• 한국식품조리과학회지
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• 제22권4호통권94호
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• pp.477-487
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• 2006

The quality characteristics of dough and French breads containing dietary fibers, which were resistant starches (RS3 and RS4 types) and commercial non-starch polysaccharides (cellulose, pectin and chitosan), were investigated. The pH of the dough containing all dietary fiber except pectin was greater than that of control and was increased with increasing addition level. There was no correlation between pH and the expansion ratio of dough. As the level of added dietary fibers became high, the bread baking loss decreased, and the order of specific bread volume was 5% cellulose < 5% pectin < control bread, with no significant difference in specific volume. When a high level of dietary fibers was added to wheat flour, a complex phase appeared due to the formation between the network structure of additives and wheat gluten, and starch granules were heavily masted by the increased development of gluten-network matrix after the first fermentation like a wide spread net. Comparing the colorimetric changes of breads with the same added ratio (10%) of dietary fibers, the cellulose and RS4 addition breads had lower levels and the pectin-added bread had the highest value in the redness, while the chitosan-added bread had the highest value in the yellowness. Breads with a high level of dietary fibers showed increased hardness, gumminess, and brittleness and decreased springiness and cohesiveness. By sensory data, breads with 5% NSP and 10% RS addition showed high overall acceptability, with higher sensory RS score, compared to NSP addition. In conclusion, it was suggested that bread with lower than 10% RS or 5% NSP addition based on the amount of wheat flour, was acceptable with no considerable change in preference/overall quality and processing in bread-making.

• 한국광학회지
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• 제5권1호
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• pp.113-119
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• 1994

발진파장이 $1.3\mu\textrm{m}$인 Ridge Waveguide Distributed Feedback Laser Diode(RWG-DFB-LD)를 제작하고 특성을 평가하였다. 회절격자 형성은 광간섭무늬 노광법을 이용하였고 결정성장은 LPE로 수행하였다. 제작된 RWG-DFB-LD의 발진 임계전류는 67 mA이었고, 1296.5 nm 파장에서 측모우드 억제율 30 dB 이상으로 단일 종모우드 발진하였다. 금지대역폭 측정에 의한 회절격자 결합계수(k)는 $40cm^{-1}$로 평가되었다. 소신호 변조특성평가 펼과 제작한 RWG-DFB-LD는 1.2Ith에서 1.99GHz의 변조대역폭$(f_{-3dB})$ 특성을 보였다.