• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.598-606
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• 2022

With the advancement of industry, the use of various sustainable energy sources and solutions to problems affecting the environment are being actively requested. From this point of view, it is intended to directly burn unused biogas to use it as energy and to solve environmental problems such as greenhouse gases. In this study, a new type of cavity matrix combustor capable of low-emission complete combustion without complex facilities such as separation or purification of biogas produced in small and medium-sized facilities was proposed, and CFD numerical calculation was performed to understand the performance characteristics of this combustor. The cavity matrix combustor consists of a burner with a rectangular porous microwave receptor at the center inside a 3D cavity that maintains a rectangular parallelepiped shape composed of a porous plate that can store heat in the combustor chamber. As a result of numerical calculation, the biogas supplied to the inlet of the combustor is converted to CO and H₂, which are intermediate products, on the surface of the 3D matrix porous burner. And then the optimal combustion process was achieved through complete combustion into CO₂ and H₂O due to increased combustibility by receiving heat energy from the microwave heating receptor.

• 한국산업보건학회지
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• 제30권2호
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• pp.153-162
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• 2020

Objectives: 3D printing technologies have become widely developed and are increasingly being used for a variety of purposes. Recently, the evaluation of 3D printing operations has been conducted through chamber test studies, and actual workplace studies have yet to be completed. Therefore, the objective of this study was to determine the emission of volatile organic compounds(VOCs), metals, and particles from printing operations at a workplace. This included monitoring conducted at a commercial 3D printing service workplace where the processes involved material extrusion, material jetting, binder jetting, vat photo polymerization, and powder bed fusion. Methods: Area samples were collected with using a Tenax TA tube for VOC emission and MCE filter for metals in the workplace. For particle monitoring, Mini Particle Samplers(MPS) were also placed in the printer, indoor work area, and outdoor area. The objective was to analyze and identify particles' size, morphology, and chemical composition using transmission electron microscopy with energy dispersive spectroscopy(TEM-EDS) in the workplace. Results: The monitoring revealed that the concentration of VOCs and metals generated during the 3D printing process was low. However, it also revealed that within the 3D printing area, the highest concentration of total volatile organic compounds(TVOC) was 4,164 ppb at the vat photopolymerization 3D printing workplace, and the lowest was 148 ppb at the material extrusion 3D printing workplace. For the metals monitoring, chromium, which, is carcinogenic for humans, was detected in the workplace. As a characteristic of the particles, nano-sized particles were also found during the monitoring, but most of them were agglomerated with large and small particles. Conclusions: Based on the monitoring conducted at the commercial 3D printing operation, the results revealed that the concentration of VOCs and metals in the workplace were within Korea's occupational exposure limits. However, due to the emission of nano-sized particles during 3D printing operations, it was recommended that the exposure to VOCs and metals in the workplace should be minimized out of concern for workers' health. It was also shown that the characteristics of particles emitted from 3D printing operations may spread widely within an indoor workplace.

• 분석과학
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• 제23권2호
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• pp.138-146
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• 2010

환경부에서는 오염물질 다량 방출 건축자재의 효율적인 관리를 위해 다중이용시설 등의 실내 공기질 관리법의 시행 규칙 일부를 개정하였다. 특히 액상건축 자재인 실란트의 경우 시험방법과 초과기준이 함께 개정되어 기존 관리 수준과 개정 관리 수준의 직접적인 비교가 불가능하다. 따라서 이 연구에서는 실란트의 개정 시험방법의 각 요소들이 오염물질 방출강도에 미치는 영향과 타당성을 기존 시험방법에 대비하여 검토하였다. 이를 통하여 개정된 오염물질 방출 관리기준을 평가하였다. 특히 실란트는 제품마다 완전경화에 소요되는 시간의 편차가 커서 시험기간 내에 완전히 경화되지 않는 제품들도 다수 있는 것으로 나타났다. 그래서 경화시간이 빠른 제품들만 대상으로 개정된 시험방법을 적용하여 실험하였다. 그 결과 개정된 실란트의 관리기준은 기존의 관리기준에 비해 2.5 배 이상 약화된 것으로 나타났다. 개정된 실란트의 시험방법을 모든 실란트 제품에 적용하기 위해서는 시험기간을 연장하거나 실란트 시험편을 빨리 경화시킬 수 있는 시험방법으로 개선이 필요하다.

• Journal of the Korean Wood Science and Technology
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• 제45권5호
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• pp.580-587
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• 2017

목섬유 단열재는 친환경 고단열성에 기인하여 저에너지 및 쾌적하고 안전한 주거 공간 형성을 위한 핵심 건축재료로 고려된다. 본 연구에서는 서로 다른 접착제로 제조한 단열재용 저밀도섬유판의 폼알데하이드(HCHO) 총휘발성유기화합물(TVOC) 방출 및 화염에 의한 연소 형상을 조사하였다. 멜라민 요소 폼알데하이드(MUF), 페놀 폼알데하이드(PF), emulsified methylene diphenyl diisocyanate (eMDI) 및 라텍스 수지 접착제 등으로 제조한 저밀도섬유판 4종의 HCHO TVOC 방출 특성 및 연소 형상은 각각 챔버법과 화염실험을 통하여 분석하였다. 그 결과 MUF, eMDI, 라텍스 수지 접착제로 제조한 저밀도섬유판들은 Super $E_0$급의 우수한 HCHO 저방출 성능을 나타냈다. 반면 PF 수지로 제조된 저밀도섬유판은 $E_0$급 성능을 나타내었다. TVOC 방출량은 모든 저밀도섬유판이 국내 실내공기질 기준(이하 $400{\mu}g/m^2{\cdot}h$)을 만족하였으며, 기존 석유계 합성원료 기반의 단열재보다 낮은 수치를 나타냈다. 그중에서도 특히 eMDI 수지 접착제로 제조한 경우에서는 HCHO 및 TVOC 방출량이 각각 $0.14mg/{\ell}$, $12{\mu}g/m^2{\cdot}h$로 가장 낮게 측정되었다. 그러나 eMDI로 제조한 저밀도섬유판에서 방출된 VOC의 성분을 조사한 결과, 톨루엔 성분($3{\mu}g/m^2{\cdot}h$)이 소량 검출되었다. 화염에 의한 연소시험에서는 MUF 수지 접착제로 제조한 저밀도섬유판이 다른 경우에 비하여 연소 후 비교적 가장 양호한 형상을 나타내었다. HCHO 및 TVOC 방출 특성, 연소 형상을 고려하였을 때 단열재용 저밀도섬유판은 MUF 수지 접착제가 가장 적합할 것으로 판단된다.

• 한국대기환경학회지
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• 제30권1호
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• pp.77-87
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• 2014

In this study, an experimental approach to measure a suite of low weight hydrocarbons was investigated with an emphasis on ethylene (EL) along with many others (ethane (EA), propane (PA), propylene (PL), n-butane (BA), acetylene (AL), methyl acetylene (ML)). Their concentrations were quantified using GC-FID system equipped with thermal desorption (TD) system. The TD-based analysis was conducted using both Link Tube/Thermal Desorber (LT/TD) method and Modified Injection through a Thermal Desorption (MITD) method. The results of these analyses were evaluated in a number of respects. The system allowed the detection of all compounds except methane with the mean response factor (RF) of 10.28 (EA) to 11.94 (PL). The method detection limits of target compounds were seen in the range of 0.027 (ML) to 0.146 ng (BA). The emission flux of some environmental samples (fruits), when measured using a small flux chamber system, fell in the range of 0.14 (AL: Kiwi) to $181ng{\cdot}g^{-1}{\cdot}hr^{-1}$ (EL: Apple Peel). The results of this study confirm that the experimental approach developed in this study allows to accurately measure emissions of low weight hydrocarbons (LWHC) like ethylene from various natural and man-made source processes.

• 동력기계공학회지
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• 제19권2호
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• pp.49-56
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• 2015

As an alternative fuel that can be used in SI engine, LPG is one of clean fuels with larger H/C ratio compared to gasoline, low $CO_2$ emission, and small amount of pollutants such as sulfur compounds. When LPG is used in spark ignition engine, volumetric efficiency of the engine can be improved and pumping loss can be reduced by performing direct injection into the combustion chamber instead of port fuel injection. LPG-DI engine allows for lean combustion and stratified combustion under low load. In case of stratified combustion, air fuel ratio can be greatly increased compared to theoretic mixture ratio combustion. Improved thermal efficiency of the engine and reduced pumping loss can be expected from stratified combustion. Accordingly in this study, an experimental apparatus for visualization was designed and manufactured to study the combustion process of LPG after injection and ignition, intended to examine ignition probability and combustion characteristics of spark ignition direct injection(SIDI) LPG fuel. Ambient pressure, ambient temperature and fuel injection pressure were found as important variables that affect ignition probability and flame propagation characteristics of LPG-air mixture. Also, it was verified that the injected LPG fuel can be directly ignited by spark plug under appropriate ambient conditions.

• 한국분말재료학회지
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• 제12권3호
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• pp.167-173
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• 2005

Production of weakly agglomerated nanopowders with the characteristic size of about 10 nm and a narrow particle size distribution is still a topical problem especially if the matter is an acceptable output (>50 g/hour), a high purity of the final product, and a low (energy consumption. The available experience and literature data show that the most promising approach to production of such powders is the evaporation-condensation method, which has a set of means for heating of the target. From this viewpoint the use of pulsed electron accelerators for production of nanopowders is preferable since they allow a relatively simple adjustment of the energy, the pulse length, and the pulse repetition rate. The use of a pulsed electron accelerator provides the following opportunities: a high-purity product; only the target and the working gas will interact and their purity can be controlled; evaporation products will be removed from the irradiation zone between pulses; as a result, the electron energy will be used more efficiently; adjustment of the particle size distribution and the characteristic size of particles by changing the pulse energy and the irradiated area. Considering the obtained results, we developed a design and made an installation for production of nanopowders, which is based on a hollow-cathode pulsed gas-filled diode. The use of a hollow-cathode gas-filled diode allows producing and utilizing an electron beam in a single chamber. The emission modulation in the hollow cathode will allow forming an electron beam 5 to 100 ms long. This will ensure an exact selection of the beam energy. By now we have completed the design work, manufactured units, equipped the installation, and began putting the installation into operation. A small amount of nanopowders has been produced.

• 한국대기환경학회지
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• 제26권6호
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• pp.690-696
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• 2010

Abatement of perfluorocompounds (PFCs) used in semiconductor and display industries has received an attention due to the increasingly stricter regulation on their emission. In order to meet this circumstance, we have developed a radio frequency (RF) driven plasma reactor with multiple annular shaped electrodes, characterized by an easy installment between a processing chamber and a vacuum pump. Abatement experiment has been performed with respect to $CF_4$, a representative PFCs widely used in the plasma etching process, by varying the power, $CF_4$ and $O_2$ flow rates, $CF_4$ concentration, and pressure. The influence of these variables on the $CF_4$ abatement was analyzed and discussed in terms of the destruction & removal efficiency (DRE), measured with a Fourier transform infrared (FTIR) spectrometer. The results revealed that DRE was enhanced with the increase in the discharge power and pressure, but dropped with the $CF_4$ flow rate and concentration. The addition of small quantity of $O_2$ lead to the improvement of DRE, which, however, leveled off and then decreased with $O_2$ flow rate.

• 공업화학
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• 제28권5호
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• pp.501-505
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• 2017

급격한 도시화와 인구 증가로 인한 건물의 밀폐성 증가로 심각한 실내 공기 오염을 야기하고 있다. 몇몇 실내 공기오염물질 중 페인트에서 방출되는 휘발성 유기화합물(VOCs)이 주요 관심사이다. 따라서 친환경적인 페인트 제품 개발에 대한 요구가 증가하고 있다. 본 연구에서는 점토광물인 견운모를 사용하여 벽마감용 천연페인트를 제조하였다. 소규모 챔버를 사용하여 벽마감용 천연페인트에 존재하는 독성물질 확인 실험을 하였으며, 2개의 상업용 페인트와 비교 분석하였다. 총 VOC 양은 trace로 권장 실내 공기질 기준보다 낮은 것으로 나타났다. 벽마감용 천연페인트에서 톨루엔은 검출되지 않았으며 포름알데히드가 trace 레벨로 측정되었다. 독성지수 분석결과 2가지 친환경 상업용 페인트와 비교하여 본 연구에서 개발된 천연페인트가 낮은 유해물질 방출을 나타내었다. 건축자재등급 실험에서 벽마감용 천연페인트가 1등급으로 분류되었다. 이상의 연구결과에서 나타난 바와 같이 벽마감용 천연페인트의 주성분으로 견운모를 사용하는 것이 실내 공기질을 관리하는데 유용할 것이라 판단된다.

• 센서학회지
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• 제10권5호
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• pp.292-303
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• 2001

본 연구에서는 수평형 전계 방출 소자를 제작하고 그 특성을 측정하였다. 이를 진공자장 센서에 이용하기 위하여 Lorentz 원리를 응용하여 센서를 설계하고 제작하였다. $POCl_3(10^{20}cm^{-3})$ 도핑된 다결정 실리콘을 전계 방출 소자의 음극 및 양극 재료로 이용하였으며 그 두께는 각각 $2\;{\mu}m$였다. PSG(두께 $2\;{\mu}m$)를 희생층으로 사용하여 최종 단계에서 불산을 이용하여 제거하고 승화건조법을 이용하여 소자의 기판 점착 현상을 방지하였다. 제작된 소자를 유리기판 #1 위에 silver paste로 고정시키고 Cr 전극 패드와 와이어본딩 한 뒤 진공내에서 양극접합공정을 이용하여 소자를 $1.0{\times}10^{-6}\;Torr$에서 진공 실장하였다. 실장 후 게터를 활성화하여 내부진공도를 향상시켰다. 이렇게 패키징된 소자는 두달여 기간 동안 특별한 특성저하 없이 잘 동작되었으며 그 이상의 기간에 대해서는 확인하지 못하였다. 패키징된 자장 센서는 패키징하기 전 진공챔버 내에서 보인 특성치와 별다른 차이 없이 잘 동작되었으며 단지 약간의 전류 감소 현상만이 관찰되었다. 측정된 센서의 감도는 약 3%/T로서 작은 값이었으나 그 가능성을 확인할 수는 있었다.