• Applied Chemistry for Engineering
• /
• v.10 no.7
• /
• pp.990-995
• /
• 1999

To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with ethylene diamine(EDA) and hexamethylene diamine(HMDA) in a stoichiometrically equivalent ratio. From this work, the effect of linear amine curing agents on the thermal and mechanical properties is significantly influenced by the chemical structure or chain length of curing agents. In contrast, the results show that the DGEBA/EDA system having the two carbons had higher values in the thermal stability, maximum conversion of epoxide, density, glass transition temperature, tensile modulus, flexural strength, and flexural modulus than the DGEBA/HMDA system having the six carbons, whereas the DGEBA/EDA cure system had relatively low values in the shrinkage(%), thermal expansion coefficient, tensile strength, and had similar values in the maximum exothermic temperature, and conversion of epoxide compared to the DGEBA/HMDA cure system. This findings indicate that packing ability in the HMDA structure affects the thermal and mechanical properties.

• Journal of Korea Soil Environment Society
• /
• v.4 no.3
• /
• pp.57-65
• /
• 1999

Generation of gaseous ammonia has been a major problem in composting facilities. Microbial inocula. KMT-199(brand name: CompoBac$^{TM}$). was developed in INBI0NET CORPORATION and tested in the field for its ammonia reducing capability. When KMT-199 was applied. a ten-fold increase of mesophilic and thermophilic microorganisms was observed during the early stage of composting process. Also. the temperature and pH of early stage compost increased at a higher rate when compared to control. KMT-199 treated compost reached highest temperature of $75^{\circ}C$at day 9, indicating treatment could shift the maximum composting temperature to 3 days earlier The highest temperature also reached $3^{\circ}C$ higher than the control. The pH of compost gradually increased during composting. KMT-199 treated compost reached a plateau of pH 9.32 at day 15 after treatment, and then slowly decreased thereafter. On the other hand. pH of the control steadily increased until day 38 of composting. 29% reduction of gaseous ammonia generation during composting was observed compared to that of the control. KMT-199 amended compost resulted in a higher germination rate of radish seeds than the control. These results indicate that application of microbial inocula facilitates degradation of organic materials, including ammonia during the composting process.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.12
• /
• pp.1013-1019
• /
• 2014

Solid-liquid Phase Change Material(PCM) as a thermal control hardware for the electro-optical payload of low earth orbit satellite is numerically studied which can be substituted with Thermal Buffer Mass(TBM). The electro-optical module in LEO satellite is periodically work and high heat is dissipated during the imaging period, however, the design temperature range is very tight and sensitive. In order to handle this problem TBM is added and as a result the time constant of the module temperature increases. TBM is made of Al6010 and its mass directly affects the system design. To save the mass PCM is suggested in this study. The latent heat of melting or solidification is very high and small amount of PCM can play a role instead of TBM. The result shows that only 12% of TBM mass is enough to control the module temperature using PCM.

• Journal of the Korean Chemical Society
• /
• v.33 no.6
• /
• pp.588-595
• /
• 1989

Log K, ${\Delta}$H and ${\Delta}$S for the complexation of $La^{3+},\;Ce^{3+}$ and $Eu^{3+}$with various multidentate ligand containing crown ether, diaza crown ether and diamine ether have been determined in methanol and acetonitril solutions at $25^{\circ}C$ by solution calorimetric titration method. The greater stability constant of $La^{3+}$-15C5 than those of 18C6 diaza [2.2] in methanol are discussed in terms of the size of metal ion and the ligand cavity and of metal ion solvation. The stabilities of $Ce^{3+}$ and $La^{3+}$ ion complexes with a various multidentate ligand in acetonitril are in the order of (diamine ether)<18C6<15C5$Ce^{3+}$, $La^{3+}$ and $Eu^{3+}$-diaza [2.2] complexes in acetonitril are increased with the following order: $Eu^{3+}$ < $La^{3+}$ < $Ce^{3+}$, that is increasing order of the optimum size and of the charge density of metal ion.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.4
• /
• pp.195-200
• /
• 2020

With the growing interest in fossil fuel depletion and environmental pollution, railroad cars operating in Korea are in progress as the conversion from diesel to electric vehicles expands. The photovoltaic system, which is applied as an example of the conversion of electric vehicles, is infinite and pollution-free, and can produce energy without generating hazards such as air pollution, noise, heat, and vibration, and maintain fuel transportation and power generation facilities. There is an advantage that is rarely needed. However, the amount of electricity produced depends on the amount of solar radiation by region, and the energy density is low due to the power generation of about 25㎡/ kWp, so a large installation area is required and the installation place has limited problems. In view of these problems, many studies have been applied to fuel cells in the railway field. In particular, the plan to link the fuel cell power generation system railroad power supply system must be linked to the power supply system that supplies power to the railroad, unlike solar and wind power. Therefore, it has a close relationship with railroad cars and the linkage method can vary greatly depending on the system topology. Therefore, in this paper, we study the validity through simulation modeling related to linkage analysis according to system topology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.20-20
• /
• 2008

최근 LEDs가 동일 효율의 전구에 비해 에너지 절감 효과 크며 신뢰성이 뛰어나다기 때문에 기존 광원을 빠르게 대체해 나가고 있다. 특히 자외선 파장을 가지는 LEDs는 발열이 낮아 냉각장치가 필요 없으며, 수명이 길어 기존 UV lamp에 비해 많은 장점을 가지고 있기 때문에 많은 관심을 밭고 있다. 그럼에도 불구하고 자외선 LEDs는 제조 단가가 높고 power가 낮아 소요량이 많은 등 아직 해결해야 할 부분이 많기 때문에 이를 해결하기 위해 여러가지 재료와 다양한 구조가 고려되고 있다. 그 중 ZnO는 II-VI족 화합물 반도체로써 UV영역의 넓은 밴드갭(3.37eV)을 가지는 투명한 재료이다. 특히 ZnO는 60meV의 큰 엑시톤 결합에너지를 가지며, 가시광 영역에서 높은 투과율을 가지고, 상온에서 물리적, 화학적으로 안정하기 때문에 UV sensor, UV laser, UV converter, UV LEDs 등 광소자 분야에서 연구가 활발히 진행되고 있다. ZnO가 광소자의 발광재료로써 높은 효율을 얻기 위해서는 결정성을 높여 내부 결함을 감소시키며, 발광 면적을 높일 수 있는 구조가 요구된다. 특히 MOCVD 법으로 성장한 나노막대는 에피성장되어 높은 결정성을 기대할 수 있으며, 성장 조건을 조절함으로써 나노막대의 aspect ratio와 밀도 제어할 수 있기 때문에 표면적을 효과적으로 넓혀 높은 발광효율을 얻을 수 있다. 본 실험에서는 MOCVD 법으로 실리콘과 사파이어 기판 위에 다양한 성장 온도를 가진 나노구조를 성장 시키고 온도에 따른 형상 변화와 특성을 평가하였다. ZnO 의 성장온도가 약 $360^{\circ}C$ 일 때, 밀도가 조밀하고 기판에 수직 배열한 균일한 나노막대가 성장되었으며 우수한 결정성, 광학적 특성이 나타남을 SEM, TEM, PL, XRD를 사용하여 확인하였다.

• Advanced Industrial SCIence
• /
• v.2 no.2
• /
• pp.9-15
• /
• 2023

Since silicone rubber heaters are flexible, they can be directly attached or installed in objects to be heated even in flat, curved or three-dimensional shapes. Since the current heating method heats the entire object to be heated and raises it to a required temperature, ignoring areas or positions where heat is not required, partial intensive heating cannot be performed. When using multi-heating zones, rather than heating the entire object to be heated, only the parts that need heat are intensively heated according to the process, so it is possible to heat quickly by local location by applying different amounts of heat with a small amount of electric capacity to each place that needs heat, and heat energy can reduce. In this study, the temperature and heating time of the partially concentrated region in the multi-heating region structure are measured so that a uniform temperature or temperature difference occurs in the region requiring thermal fusion. In order to determine the optimal power density range and reduce capacitance, the safety of a silicon rubber heater manufactured with a multi-heating zone structure is investigated. If the silicon rubber heater is manufactured in a multi-heating method, the multi-intensive heating technology can be ideally applied to all heating processes.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.1
• /
• pp.48-59
• /
• 2018

This study was conducted to suggest the effective management and recycling processes of coffee waste, which can be easily obtained from coffee shops and coffee-related products industries. Prior to the fabrication of pellets, the potential of coffee waste as a raw material of pellet was investigated through the examination of its chemical compositions and fuel characteristics. Major gradient included in coffee waste was holocellulose, followed by fat/oil and protein. Coffee waste contained a small quantity of ash (0.7%), such as calcium, sodium, potassium and magnesium. Interestingly, coffee waste was easily dried probably due to its porous structure. Pellets fabricated with coffee waste and larch sawdust showed good fuel characteristics, such as moisture content, ash content, density and durability. The pellets exceed greatly the minimum requirements of $1^{st}$-grade wood pellet standard designated by National Institute of Forest Science (NIFOS). Particularly, the high calorific value of coffee waste showed the potential as a raw material of pellet. However, owing to high nitrogen and sulfur contents, coffee waste is like to be used as a raw material of wood pellet for combined heat and power plants equipped with a reduction system of $NO_x$ and $SO_x$ gases. On the other hand, 91 wt% larch sawdust and 9 wt% coffee waste are required to fabricate the $1^{st}$-grade wood pellets designated by NIFOS. Pellets fabricated with the conditions are estimated to have nitrogen content of 0.298% and sulfur content of 0.03%. Lastly, if amounts of coffee waste and sawdust in the production of wood pellets are adequately adjusted according to its purchasing price, the manufacturing cost of pellet can effectively be reduced. In addition, it is expected tp prepare the effective recycling process of waste and to relieve the environmental burden with the reduction of waste from the commercialization of coffee waste/larch pellets.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.6
• /
• pp.1572-1578
• /
• 2007

The specified wastes consist of waste acid, waste alkali, waste oil, waste organic solvent, waste resin, dust, sludge, infectious waste, and others. Among these specified wastes, a great portion is liquid phase wastes. The purpose of this study is to develop the high temperature and high pressure (HTHP) treatment system for decomposition of the liquid phase specified waste (LPSW). For this, we analyzed the physical and chemical properties of the LPSW such as density, proximate analysis, ultimate analysis, heating values, and designed 0.3 ton/day HTHP treatment system. The LPSW tested in this experiment were prepared by adding TCE(trichloroethylene) and toluene to liquid phase waste which was brought into the commercial waste treatment company. The average density of waste oil (25 samples), waste resin (5 samples), and waste solvent (12 samples) was 0.99 g/mL, 0.91 g/mL, and 0.93 g/mL, respectively. And the average lower heating value of waste oil, waste resin, and waste solvent was 8,294 kcal/kg, 5,809 kcal/kg, and 7,462 kcal/kg, respectively. The DRE (Destruction & Removal Efficiency) of TCE and toluene were 99.95% and 99.73% at atmospheric pressure conditions and that were 99.99% and 99.82% at pressurized conditions, respectively. These results showed that TCE/toluene mixtures were properly decomposed over about 99.73% of DRE by the HTHP treatment system and pressurized conditions were more effective to destroy those pollutants than atmospheric pressure conditions. Also these systems could be directly applied to industries which try to treat the liquid phase specified waste within the regulation limit.