We have investigated a glass-forming region of V2O5- P2O5-ZnO glass and the effects of the addition of modifier oxides (B2O3) to the glass systems as a sealing material to improve the adhesion between the glass frits and a soda lime substrate. Thermal properties and coefficient of thermal expansion were measured using a differential scanning calorimetry, a dilatometer and a hot stage microscopy. Structural changes and interfacial reactions between the glass substrate and the glass frit after sintering (at 400 oC for 1 h) were measured by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. The results showed that the adhesion strength increases as the content of B2O3 at 5 mol% increases because of changes in the structural properties. It seems that the glass structures change with B2O3, and the Si4+ ions from the substrate are diffused to the sealing glass. From these results, we could understand the mechanism of strengthening of the adhesion of soda lime silica substrate by ion-diffusion from the substrate to the glass.

The influence of NiCrAlY bond coating on the adhesion properties of an Fe thermal coating sprayed on an Al substrate was investigated. By applying a bond coat, an adhesion strength of 21MPa was obtained, which was higher than the 15.5MPa strength of the coating without the bond coat. Formation of cracks at the interface of the bond coat and the Al substrate was suppressed by applying the bond coat. Microstructural analysis of the coating interface using EBSD and TEM indicated that the dominant bonding mechanism was mechanical interlocking. Mechanical interlocking without crack defects in the coating interface may improve the adhesion strength of the coating. In conclusion, the use of an NiCrAlY bond coat is an effective method of improving the adhesion properties of thermal sprayed Fe coatings on Al substrates.

To increase the stability of anthocyanin from black rice, β-cyclodextrin (β-CD) formed a complex with anthocyanin, and thermal and UVB stability of the complex was investigated at various pH levels. The formation of β-CD complex with anthocyanin was confirmed by the decreased UV-Vis spectrophotometer absorbance (at 511nm) with increasing the concentration of β-CD at pH 2, 2.5, 3, 4, and 5. ABTS (2, 2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid)assay was conducted to measure radical scavenging capacity (RSC) of the complex at pH 2, 4, 6, and 8, after which the RSCs were recorded over the 24 h heating(95°C) and 24 h UVB irradiating periods. The RSC values of the complexes increased as the β-CD concentration increased (0.1-2%) at pH 6 and 8. Upon thermal treatment, the RSC readings of the complexes tended to decrease to a lesser extent compared to the anthocyanin control (without β-CD) at pH 2. This result suggests that the thermal stability of anthocyanin was more retained in the presence of β-CD at low pH (pH 2). However, in the case of UVB irradiation, the effect of β-CD complex on the anthocyanin RSC was not significant, though the RSC values for both the anthocyanin control and complexes trended downward as the UVB irradiation time increased at all pH ranges except for pH 8 (no downward trend). In short, this study suggests that the effect of β-CD complex on the stability of anthocyanin antioxidant capacity depends on pH and the susceptibility to the degradation process.

Hydrogen sulfide (H2S) emitted from various sources is a major odorous compound, and non-thermal plasma (NP) has emerged as a promising technique to eliminate H2S. This study was conducted to investigate lab-scale and pilot-scale NP reactors using corona discharge for the removal of H2S, and the effects of relative humidity, applied electrical power on reactor performance and ozone generation were determined. A gas stream containing H2S was injected to the lab-scale NP reactor, and the changes in H2S and ozone concentration were monitored. In the pilotscale NP experiment, the inlet concentration and flow rate were modified to determine the effect of relative humidity and applied power on the NP performance. In the lab-scale NP experiments, H2S removal was found to be the 1st-order reaction in the presence of ozone. On the other hand, when plasma reaction and ozone generation were initiated after H2S was introduced, the H2S oxidation followed the 0th-order kinetics. The ratio of indirect oxidation by ozone to the overall H2S removal was evaluated using two different experimental findings, indicating that approximately 70% of the overall H2S elimination was accounted for by the indirect oxidation. The pilotscale NP experiments showed that H2S introduced to the reactor was completely removed at low flow rates, and approximately 90% of H2S was eliminated at the gas flow rate of 15 m3/min. Furthermore, the elimination capacity of the pilot-scale NP was 3.4 g/m3·min for the removal of H2S at various inlet concentrations. Finally, the experimental results obtained from both the lab-scale and the pilot-scale reactor operations indicated that the H2S mass removal was proportional to the applied electrical power, and average H2S masses removed per unit electrical power were calculated to be 358 and 348 mg-H2S/kW in the lab-scale and the pilot-scale reactors, respectively. To optimize energy efficiency and prevent the generation of excessive ozone, an appropriate operating time of the NP reactor must be determined.

The effect of CNT diameters on properties of CNT-polyamide composites was investigated such as electrical conductivity, tensile strength and thermal conductivity. To get different diameter distributions of CNTs, several portions of Mo and Fe in Mo-Fe/MgO catalysts were synthesized by a combustion method at 600℃. And all CNTs growed at 900℃ with 3 SLM methane and 1 SLM hydrogen for 40min. Four kinds of CNTs with different diameter distributions, such as 1~3nm, 3~7nm, 7~13nm, and 10~30nm, were selected to make CNT-polyamide composites. Each composite was manufactured by a solution mixing using bar-type ultra-sonicator in the CNT portions from 1phr to 50phr. And electrical conductivity, tensile strength, and thermal conductivity were measured. Three properties of CNT-polyamide composite, manufactured with 10nm diameter, were more excellent compared to other composites, with electrical conductivity  Ω at 7phr, thermal conductivity 2.4.W/mK at 40phr, tensile strength 60MPa at 30phr. CNTs with a diameter of 10nm were superior to other diameters for the multi-functional composite such as CNT-polyamide composites.

TiO2 nanowires were grown by thermal oxidation of TiO powder in an oxygen and nitrogen gas environment at 1000 oC. The ratio of O2 to N2 in an ambient gas was changed to investigate the effect of the gas ratio on the growth of TiO2 nanowires. The oxidation process was carried out at different O2/N2 ratios of 0/100, 25/75, 50/50 and 100/0. No nanowires were formed at O2/N2 ratios of less than 25/75. When the O2/N2 ratio was 50/50, nanowires started to form. As the gas ratio increased to 100/0, the diameter and length of the nanowires increased. The X-ray diffraction pattern showed that the nanowires were TiO2 with a rutile crystallographic structure. In the XRD pattern, no peaks from the anatase and brookite structures of TiO2 were observed. The diameter of the nanowires decreased along the growth direction, and no catalytic particles were detected at the tips of the nanowires which suggests that the nanowires were grown with a vapor-solid growth mechanism.

ZnO micro/nanocrystals at large scale were synthesized through the thermal evaporation of Al-Zn mixtures under air atmosphere. The effect of synthetic temperature and time on the morphology of the micro/nanocrystals was examined. It was found that the temperature and time affected the morphology of the ZnO crystals. At temperatures below 900 oC, no crystals were synthesized. At a temperature of 1000 oC, ZnO crystals with a rod shape were synthesized. With an increase in temperature from 1000 oC to 1100 oC, the morphology of the crystals changed from rod shape to wire and granular shapes. As the time increased from 2 h to 3 h at 1000 oC, tetrapod-shaped ZnO crystals started to form. XRD patterns showed that the ZnO crystals had a hexagonal wurtzite structure. EDX analysis revealed that the ZnO crystals had high purity. It is believed that the ZnO nanowires were grown via a vapor-solid mechanism because no catalyst particles were observed at the tips of the micro/nanocrystals in the SEM images.

This study investigates the microstructure and thermal shock properties of polycrystalline diamond compact (PDC) produced by the high-temperature, high-pressure (HPHT) process. The diamond used for the investigation features a 12~22 μm- and 8~16 μm-sized main particles, and 1~2 μm-sized filler particles. The filler particle ratio is adjusted up to 5~31% to produce a mixed particle, and then the tap density is measured. The measurement finds that as the filler particle ratio increases, the tap density value continuously increases, but at 23% or greater, it reduces by a small margin. The mixed particle described above undergoes an HPHT sintering process. Observation of PDC microstructures reveals that the filler particle ratio with high tap density value increases direct bonding among diamond particles, Co distribution becomes even, and the Co and W fraction also decreases. The produced PDC undergoes thermal shock tests with two temperature conditions of 820 and 830, and the results reveals that PDC with smaller filler particle ratio and low tap density value easily produces cracks, while PDC with high tap density value that contributes in increased direct bonding along with the higher diamond content results in improved thermal shock properties.

In this study, in order to improve the thermal and electrical properties of epoxy/graphene nanoplatelets (GNPs), surface modifications of GNPs are conducted using silane coupling agents. Three silane coupling agents, i.e. 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (ETMOS), 3-glycidoxypropyltriethoxysilane (GPTS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), were used. Among theses, GPTMS exhibits the best modification performance for fabricating GNP-incorporated epoxy composites. The effect of the silanization is evaluated using transmission electron microscopy (TEM), scanning electron microscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The electrical and thermal conductivities are characterized. The epoxy/silanized GNPs exhibits higher thermal and electrical properties than the epoxy/raw GNPs due to the improved dispersion state of the GNPs in the epoxy matrix. The TEM microphotographs and Turbiscan data demonstrate that the silane molecules grafted onto the GNP surface improve the GNP dispersion in the epoxy.

본 연구는 공기열원 히트펌프 온실에서 환기에 의해 배출되는 에너지 즉 잉여 태양에너지 및 태양열 집열기를 이용하여 축열량 및 이들 에너지를 이용한 온실의 난방효과를 실험적으로 검토하였다. 태양열 집열기의 경우, 실험기간동안 누계 수평면 일사량의 최대, 평균 및 최솟값은 각각 52.2, 22.9 및 3.2 MJ․m-2이었고, 총 일사량은 869.8 MJ․m-2 정도였다. 그리고 집열량의 최대, 평균 및 최솟값은 각각 38,118.2, 22,545.9 및 2,622.1 kcal 정도였고, 총 집열량은 856,742.6 kcal 정도인 것으로 나타났다. 잉여 태양에너지의 경우, 여러 가지 요인에 의해서 온실로부터 회수되는 열량은 다르지만, 온실로부터 회수된 총 잉여 태양에너지는 375,946.7 kcal 정도인 것으로 나타났다. 히트펌프의 경우, 설정온도를 고려하지 않고 축열된 총 축열량은 17,519,085.3 kcal이고, 이 때 소비된 소비전력량은 7,169.6 kWh정도이었고, 시스템의 성능계수는 2.84정도이었다. 그리고 온실로 공급된 난방에너지는 최저 외기온과 유사한 경향을 보이는 것으로 나타났으며, 실험기간동안 총 난방에너지는 9,554,541.9 kcal로서 시간당으로 환산하면 평균 6,653.1 kcal․h-1정도인 것으로 나타났다. 특히 실제 히트펌프에 의해 축열된 량의 54.5%정도만 이용하는 것으로 나타나 난방시스템의 개선이 필요할 것으로 판단되었다. 실험기간동안 태양열 집열기, 잉여 태양에너지 및 히트펌프에 의한 축열량을 난방에너지로 100.0% 이용할 경우, 탄소배출량은 각각 259.7, 116.9 및 5,403.5 kgCO2정도 절감시킬 수 있을 것으로 나타났다.

RBSC (reaction-bonded silicon carbide) represents a family of composite ceramics processed by infiltrating with molten silicon into a skeleton of SiC particles and carbon in order to fabricate a fully dense body of silicon carbide. RBSC has been commercially used and widely studied for many years, because of its advantages, such as relatively low temperature for fabrication and easier to form components with near-net-shape and high relative density, compared with other sintering methods. In this study, RBSC was fabricated with different size of SiC in the raw material. Microstructure, thermal and mechanical properties were characterized with the reaction-sintered samples in order to examine the effect of SiC size on the thermal and mechanical properties of RBSC ceramics. Especially, phase volume fraction of each component phase, such as Si, SiC, and C, was evaluated by using an image analyzer. The relationship between microstructures and physical properties was also discussed.

The aim of this paper is to consider the effect of annealing on the coefficient of thermal expansion (CTE) of electroplated Invar Fe-Ni alloy. The CTE of the as-electroplated alloy is lower than those of alloys annealed at 400˚C and 800˚C. XRD peaks become sharper as the as-electroplated alloy is annealed, which means the grain growth. The average grain sizes of as-electroplated and as-annealed alloys at 400˚C and 800˚C are 10 nm, 70 nm, and 2μm, respectively, as determined by TEM and EBSD analyses. The CTE variation for the various grain sizes after annealing may come from the magnetostriction effect, which generates strain due to changes in the magnetization state of the alloys. The thermal expansion coefficient is considered to be affected by nano grain size in electroplated Fe-Ni Invar alloys. As grain size decreases, ferromagnetic forces might change to paramagnetic forces. The effect of lattice vibration damping of nano grain boundaries could lead to the decrease of CTE.

본 연구에서는 다양한 실내 온열환경 및 조도에서 재실자가 느끼는 조명에 대한 감성의 변화와 작업의 종류에 따라 생체신호를 분석하여 업무에 미치는 영향에 대해 살펴보고자 하였다. 이를 위해 실내 온열환경은 PMV(predicted mean vote) 지표 값을 기반으로 환경을 구성하였고, 조명환경은 LED광원을 이용한 스탠드를 통해 조명의 밝기에 변화를 주어 다양한 실내 환경을 구성하고 실험을 진행하였다. 주어진 환경에서 설문지를 통해 조명에 대한 감성을 평가하고 종류가 다른 오류검색수정 작업을 진행하면서 뇌파와 심전도를 측정하여 변화를 분석하였다. 그 결과, 작업의 종류에 대한 모든 생체신호는 온열환경의 변화와 유의적인 차이를 보였으며, PMV 지표 값이 0.8(온도: 25 ℃, 습도: 50 %)일 경우 집중력 및 주의력이 가장 활성화 되었다. 하지만, 조도의 변화에 는 대체적으로 유의적인 차이는 보이지 않았다. 따라서 재실자의 업무 능력에 미치는 집중력은 온열환경과 밀접 함을 확인할 수 있다. 또한, 조명에 대한 주관적인 감성은 조도가 낮을수록 편안함을 느꼈으며, 조도가 높을수록 불편함을 느꼈다. 하지만 온열환경의 변화에는 유의적인 차이가 없었다.

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when the electrical current is transmitted into. Prior to the study, we have researched the potato starch’s thermal property changes during ohmic heating. Comparing with conventional heating, the gelatinization temperature and the range of potato starch treated by ohmic heating are increased and narrowed respectively. Herein, we have studied thermal property changes of wheat, corn, potato and sweet potato starch by ohmic heating as well as conventional heating. And then we measure the water holding capacity of starches. Annealing of starch is a heat treatment method heated at 3~4% below the gelatinization point. This treatment changes the starch’s thermal property. In the DSC analysis of this study, the To, Tp, Tc of all starch levels have increased, and the Tc－To narrowed. In the ohmic heating, the treatment sample is extensively changed but not with the conventional heating. From the ohmic treatment, increases from gelatinization temperature are potato (8.3℃) > wheat (5.3℃) > corn (4.9℃) > sweet potato (4.5℃), and gelatinization ranges are potato (7.9℃), wheat (7.5℃), corn (6.1℃) and sweet potato (6.8℃). In the case of conventional treatment, water holding capacity is not changed with increasing temperature but the ohmic heating is increased. Water holding capacity is related to the degree of gelatinization for starch. This result show that when treated with below gelatinization temperature, the starches are partly gelatined by ohmic treatment. When viewing the results of the above, ohmic treatment is enhanced by heating and generating electric currents to the starch structure.

집중되는 행정기관, 기업, 편의시설 등에 기인한 인구 증 가로 서울은 1㎢당 1만 6천여명의 인구가 밀집하여 살고 있다. 늘어나는 인구수용을 위해 단일면적당 층수가 높은 건물의 건설, 토지피복재료의 변화 등으로 서울도심의 열환 경은 변화해 왔으며 변화된 열환경으로 인해 발생되는 도시 열섬현상, 열대야, 대기순환 정체 등에 서울시민들은 금전 적, 신체적, 정신적 피해를 받고 있다. 특히, 더워지는 여름 철 도시기후에 의해 에어콘 사용으로 지속적인 인공열이 방출되고, 그에 따른 온도 상승에 의한 악순환이 발생하였 다. 악화되는 열환경을 개선하기 위하여 수공간 및 공원을 조성해 영향을 상쇄시키고자 하고있다. 이에 본 연구는 면 적 녹지로 인한 주변 열환경에 미치는 영향과 범위를 파악 하여, 도심 열환경 균형을 위한 기초자료를 구축하고 향후 도시개발시 녹지의 필요량을 정량적으로 밝히고자 한다. 연구대상지인 선정릉은 서울시 강남구에 위치하며, 유네 스코 세계문화유산으로 지정된 곳으로 토지이용 밀도가 높 은 도시지역에서 냉섬역할을 수행하고 있는 지역이었다. 선 정릉 인근 지역은 유사한 토지이용으로 열환경에 영향을 미치는 요인이 적어 면적 녹지에 의한 주변 열환경 조사․분 석의 조건이 양호하였다. 선정릉의 면적은 24.06ha이었으 며, 내부의 현존식생은 잔존산림의 소나무림(27.3%), 잣나 무림(2.6%)과 참나무류림(33.9%), 계곡부 오리나무림 (4.9%), 왕릉을 중심으로 한 잔디식재지(14.0%)와 조경수 목식재지(13.8%), 시설지(1.0%) 등 이었다. 선정릉이 주변 열환경에 미치는 영향거리를 산정하기 위 하여 기존 논문을 고찰한 결과, 면적이 18.53ha인 공원이 최대 370m의 주변 기온 완화에 영향을 미친다는 결과를 반영하여, 면적이 24.06ha인 선정릉의 영향범위를 최대 500m에 이를 것으로 가설설정을 하였다. 측정기간은 3∼7 월간 매월 하순 중 날씨가 맑은 날에 실시하였고, 측정시간 은 12:00∼22:00까지 1시간씩 구분하여 5회 측정하였다. 측정지점은 선정릉을 중심으로 4개의 방향을 나누었으며, 각 방향은 선정릉과 연접한 지역에서부터 50m마다 휴대용 열선식 온도 측정기(TES-1341)를 사용하여 8∼10곳(0∼ 500m)의 기온을 측정하였다. 각 지역별 기온 측정시 대조 구로서 노선의 진행방향에서 반대방향인 선정릉쪽으로 50m 내부로 들어가 기온을 측정하여 비교하였다. 조사구 가 지역은 선정릉의 북측으로 총 11개소의 측점 을 선정하여 기온을 측정하였다. 1∼5번 지점은 평지이며, 그 중 3번과 4번 조사구 사이는 봉은사로가 위치하였다. 6∼8번 지점은 평지에 가까운 사면지역으로 특히 8번 지점 은 경사가 높은 사면 아래이었으며, 9∼10번은 경사가 급한 사면에 위치하였다. 조사구 나 지역은 선정릉의 동측으로 총 10개소의 측점이며 모두 평지지형이었고, 조사구 4번과 5번 사이에 삼성로가 위치하였다. 조사구 다 지역은 선정릉 의 남동측 방향으로 총 11개의 측점을 선정하여 기온을 측 정하였다. 1∼4번은 평지이며 3번과 4번 사이는 테헤란로 가 있으며, 5번 지점은 경사가 급한 사면이며, 6번과 7번은 인근 지형에서 가장 높은 지역이었고, 8∼10번은 사면 아래 평지였다. 조사구 라 지역은 총 11개의 측점으로 1∼3번, 5∼7번 지점은 사면이며, 4번 지점은 인근 지형에서 최고점 이었으며, 8∼10번 지점은 평지지형이었다. 조사구는 선정릉의 내부 열환경 변화와 주변 열환경과의 관계를 분석하고자 계곡부 4개소, 사면부 6개소, 능선부 7 개소로 구분하였으며, 계곡부에 AWS(Automatic Whether System)를 설치하여 선정릉 내부의 미기상(기온, 습도, 풍 향, 풍속)을 측정하였다. SPSS 17.0 프로그램을 활용하여 선정릉으로부터의 거리 와 기온과의 관계를 밝히기 위해 매월 조사지역별 측정 자 료로 상관분석을 실시한 결과, 6월 라 지역에서 0.05 수준의 양의 상관관계가 유의성이 인정되었고, 6월 다 지역과, 7월 가, 나, 라 지역이 0.01 수준의 양의 상관관계가 인정되었다. 그 외 지역은 거리에 따른 기온의 상관관계가 유의미한 통 계적 수치를 얻어내지 못 하였지만, 각각의 거리에 따른 기 온변화 그래프를 비교한 결과, 각 조사지역의 영향범위를 추정할 수 있었다. 가 지역은 최대 350m까지 영향을 미쳤으 며, 평균 250m까지 영향을 미치고 있었다. 나 지역은 최대 250m, 평균 200m에 영향을 미쳤으며, 다 지역은 최대 400m, 평균 250m로 가장 영향권이 넓었다. 라 지역은 최대 350m, 평균 250m까지 영향을 미치고 있었다. 선정릉 내부지역의 지형별 기온분포를 살펴본 결과, 2가 지의 유의미한 결과가 분석되었다. 계곡부의 기온 측정이 경사가 낮은 지역으로 갈수록 기온이 더 낮게 측정되었다. 또한, 능선-사면-계곡-사면-능선 지점의 측정 기온은 해가 떠 있을 시는 유의미한 차이가 보이지 않았으나, 일몰 후인 20시경의 측정 기온을 살펴보면, 凹형의 기온분포를 보여 주고 있어, 찬공기 생성시 사면방향을 기준으로 찬공기가 내려와 도심으로 흘러들어가는 것을 추정하였다. 선정릉 내 부측정을 토대로 다 지역의 기온저감 효과가 가장 멀리까지 영향이 있었던 것은 내부에서 생성된 찬공기가 지형을 타고 다 지역으로 이동한 것에 기인한다고 분석하였다. 도시지역에서 면적 24.06ha의 면적녹지의 온도저감 효과 는 평균 200∼250m이며, 평지지형의 녹지보다는 산림지형 에서 찬공기가 생성되고 사면방향으로 내려와 도심으로 유입되기 용이하였다. 이를 통해 녹지지역과 인접한 도시지 역에 층고가 높은 건물의 조성을 지양하는 것이 도시 열환 경 문제완화에 효과적일 것으로 판단하였다. 향후 지속가능한 도시 열환경의 균형을 위해서는 녹지를 통한 완화에 앞서 현재 발생하는 열에너지의 원천적인 감소 를 지향하여야 하며, 찬공기를 생성하는 면적 24.06ha 면적 녹지의 배치는 200∼250m거리를 유지하며 조성하고, 지형 의 높낮이를 형성하고 있는 도시내부의 잔존산림과 같은 면적녹지는 보전하는 것이 인근 도시지역의 온도 저감과 에너지사용량 감소를 통해 도시민의 쾌적성 향상과 경제적 인 효과까지 가져올 수 있을 것이다.

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside of food when electrical current is flown into. In other study, we researched about soybean protein’s characteristic changes by ohmic heating. Nevertheless treated same temperature, denaturation of soybean protein were accelerated by ohmic heating than conventional heating. In this time, we studied thermal property change of potato starch by ohmic heating besides conventional heating. For this purpose, potato starch was heated at same subgelatinization temperature by ohmic and conventional heating. And thermal properties were tested using DSC. Annealing of starch is heat treatment method that heated at 3～4% below the gelatinization point. DSC analysis results of this study, the T_o, T_p, T_c of potato starch levels were increased, whereas T_c～T_o was narrowed. This thermal property changes appear similar to annealing’s result. It is thought the results shown in this study, because the heating from below the gelatinization point. 6, 12, 24, 72, and 120 hours heating at 55℃ for potato starch, T_o, T_p, T_c values continue to increased with heating time increase. The gelatinization temperature of raw potato starch was 65.9℃ and the treated starch by conventional heating at 55℃ for 120 hr was 72℃, ohmic was 76℃. The gelatinization range of conventional (72 hr) was 10℃, ohmic was 8℃. In case of 24 hours heating at 45, 50, 55, 60, 65℃ for potato starch, the result was similar to before. T_o, T_p, T_c values continue to increased and gelatinization range narrowed with heating temperature increase. In case of conventional heating at 60℃, the results of gelatinization temperature and range were 70.1℃ and 9.1℃. And ohmic were 74.4℃ and 7.5℃. When viewed through the results of the above, the internal structure of starch heated by ohmic heating was found that the shift to a more stable form and to increase the homology of the starch internal structure.

This paper reports the microstructures and thermal conductivities of -SiC composite ceramics with size and amount of SiC. We fabricated sintered bodies of -x vol.% SiC (x=10, 20, 30) with submicron and nanosized SiC densified by spark plasma sintering. Microstructure retained the initial powder size of especially SiC, except the agglomeration of nanosized SiC. For sintered bodies, thermal conductivities were examined. The observed thermal conductivity values are 40~60 W/mK, which is slightly lower than the reported values. The relation between microstructural parameter and thermal conductivity was also discussed.

High power and high efficiency has been required in internal combustion engine. Accordingly, the thermal load deformation, thermal stress and temperature on piston become higher at newly developed engines. To investigate the cooling effect of piston, a few types of piston design is presented and finite element method is carried out to analysis the heat transfer and the thermal stress. The piston which has upwards shifted cooling gallery is also analyzed to investigate the thermal load effect of oil jet cooling.

Kenaf fibers, cellulose-based natural fibers, were used as precursor for preparing kenafbased carbon fibers. The effects of carbonization temperature (700℃ to 1100℃) and chemical pre-treatment (NaOH and NH4Cl) at various concentrations on the thermal change, chemical composition and fiber morphology of kenaf-based carbon fibers were investigated. Remarkable weight loss and longitudinal shrinkage were found to occur during the thermal conversion from kenaf precursor to kenaf-based carbon fiber, depending on the carbonization temperature. It was noted that the alkali pre-treatment of kenaf with NaOH played a role in reducing the weight loss and the longitudinal shrinkage and also in increasing the carbon content of kenaf-based carbon fibers. The number and size of the cells and the fiber diameter were reduced with increasing carbonization temperature. Morphological observations implied that the micrometer-sized cells were combined or fused and then re-organized with the neighboring cells during the carbonization process. By the pre-treatment of kenaf with 10 and 15 wt% NaOH solutions and the subsequent carbonization process, the inner cells completely disappeared through the transverse direction of the kenaf fiber, resulting in the fiber densification. It was noticeable that the alkali pre-treatment of the kenaf fibers prior to carbonization contributed to the forming of kenaf-based carbon fibers.

Mono- and few-layer graphenes were grown on Ni thin films by rapid-thermal pulse chemical vapor deposition technique. In the growth steps, the exposure step for 60 s in H2 (a flow rate of 10 sccm (standard cubic centimeters per minute)) atmosphere after graphene growth was specially established to improve the quality of the graphenes. The graphene films grown by exposure alone without H2 showed an intensity ratio of IG/I2D = 0.47, compared with a value of 0.38 in the films grown by exposure in H2 ambient. The quality of the graphenes can be improved by exposure for 60 s in H2 ambient after the growth of the graphene films. The physical properties of the graphene films were investigated for the graphene films grown on various Ni film thicknesses and on 260-nm thick Ni films annealed at 500 and 700˚C. The graphene films grown on 260-nm thick Ni films at 900˚C showed the lowest IG/I2D ratio, resulting in the fewest layers. The graphene films grown on Ni films annealed at 700˚C for 2 h showed a decrease of the number of layers. The graphene films were dependent on the thickness and the grain size of the Ni films.