• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2002년도 제3회 최신 분말제품 응용기술 Workshop
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• pp.25-37
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• 2002

The most important industrial application of gamma radiation in characterizing green compacts is the determination of the density. Examples are given where this method is applied in manufacturing technical components in powder metallurgy. The requirements imposed by modern quality management systems and operation by the workforce in industrial production are described. The accuracy of measurement achieved with this method is demonstrated and a comparison is given with other test methods to measure the density. The advantages and limitations of gamma ray densitometry are outlined. The gamma ray densitometer measures the attenuation of gamma radiation penetrating the test parts (Fig. 1). As the capability of compacts to absorb this type of radiation depends on their density, the attenuation of gamma radiation can serve as a measure of the density. The volume of the part being tested is defined by the size of the aperture screeniing out the radiation. It is a channel with the cross section of the aperture whose length is the height of the test part. The intensity of the radiation identified by the detector is the quantity used to determine the material density. Gamma ray densitometry can equally be performed on green compacts as well as on sintered components. Neither special preparation of test parts nor skilled personnel is required to perform the measurement; neither liquids nor other harmful substances are involved. When parts are exhibiting local density variations, which is normally the case in powder compaction, sectional densities can be determined in different parts of the sample without cutting it into pieces. The test is non-destructive, i.e. the parts can still be used after the measurement and do not have to be scrapped. The measurement is controlled by a special PC based software. All results are available for further processing by in-house quality documentation and supervision of measurements. Tool setting for multi-level components can be much improved by using this test method. When a densitometer is installed on the press shop floor, it can be operated by the tool setter himself. Then he can return to the press and immediately implement the corrections. Transfer of sample parts to the lab for density testing can be eliminated and results for the correction of tool settings are more readily available. This helps to reduce the time required for tool setting and clearly improves the productivity of powder presses. The range of materials where this method can be successfully applied covers almost the entire periodic system of the elements. It reaches from the light elements such as graphite via light metals (AI, Mg, Li, Ti) and their alloys, ceramics ($AI_20_3$, SiC, Si_3N_4, $Zr0_2$, ...), magnetic materials (hard and soft ferrites, AlNiCo, Nd-Fe-B, ...), metals including iron and alloy steels, Cu, Ni and Co based alloys to refractory and heavy metals (W, Mo, ...) as well as hardmetals. The gamma radiation required for the measurement is generated by radioactive sources which are produced by nuclear technology. These nuclear materials are safely encapsulated in stainless steel capsules so that no radioactive material can escape from the protective shielding container. The gamma ray densitometer is subject to the strict regulations for the use of radioactive materials. The radiation shield is so effective that there is no elevation of the natural radiation level outside the instrument. Personal dosimetry by the operating personnel is not required. Even in case of malfunction, loss of power and incorrect operation, the escape of gamma radiation from the instrument is positively prevented.

• 한국자기학회지
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• 제24권6호
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• pp.197-201
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• 2014

전세계적으로 희소금속의 중요성이 높아지고 있는 가운데 일본은 2004년부터 원소전략 개념을 도입하고 2007년부터는 원소전략사업을 추진하게 되었다. 일본의 문부과학성의 "원소전략 프로젝트"는 물질과 재료를 구성하고 그 기능과 특성을 결정하는 원소의 역할과 성격을 연구하고, 물질과 재료의 기능과 특성의 발현기구를 명확히 규명함으로써, 희소원소나 유해원소를 사용하지 않는 고기능을 가진 물질과 재료를 개발하는 것을 목적으로 하고 있다. 특히, 2010년 9월 일본명 센카쿠렛도(중국명 댜오위다오)에서 중국어선과 일본순시선이 충돌하는 사건이 일어나서, 중국어선을 나포하여 영토문제, 외교, 경제 갈등으로까지 확산되었다. 일본이 국내법을 적용하여 사법처리 하려하자, 중국이 꺼낸 카드가 희소금속의 일본수출금지였다. 이 때부터 위기감을 느낀 일본은 더욱더 원소전략 프로젝트에 박차를 가하기 시작했다. 일본정부는 풍부하고 무해한 원소에 의한 대체재료의 연구, 전략원소의 유효기능의 고활용, 원소유효이용을 위한 실용재료설계기술 등 3가지 제안으로 연구테마를 2012년 2월에 공모하여, 2012년 6월 "원소전략 프로젝트" 연구영역과 연구거점 4군데를 채택하였다. 1. Dy, Nd 등을 대체할 목적의 자성재료영역. 2. Pt, Rh/Li, Co 등을 대체할 목적의 촉매/전지재료영역. 3. In, Ta 등을 대체할 목적의 전자재료영역. 4. Nb, Mo 등을 대체할 목적의 구조재료영역. 본 논문에서는 원소전략의 4개의 영역 중에서 자성재료영역의 현재까지의 연구동향에 대해서 기술하고자 한다.

• 한국응용과학기술학회지
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• 제34권1호
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• pp.12-24
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• 2017

현재 국내 엔진오일-윤활유가 배출가스에 미치는 영향에 대한 연구가 미비한 실정이며 그 실험 방법 또한 확립되어 있지 않다. 이에 엔진을 이용한 윤활유 성상 변화가 PM(Particulate Matters) 배출에 미치는 영향 평가방법을 수립하여 윤활유의 성상 및 열화가 자동차 성능과 환경성에 미치는 영향을 연구하고자 한다. 윤활유 소모 및 연소로 인한 DPF(Diesel Particulate Filter) 및 후처리 장치에 미치는 영향을 평가하는 것이 중요하며, 특히 DPF의 재생과정에서 생성되는 PM(Particulate Matters)과 Ash가 DPF에 미치는 장기적인 영향과 내부 변형 및 내구성에 대한 평가와 연구가 필요하다. 본 연구에서는 정형화 되지 않은 시험모드를 개발하였으며, 내구시험결과 High SAPs의 경우 Low SAPs(Sulfated Ash, Phosphorus and Sulfuate)보다 DPF내 Ash의 축적량이 많은 것을 확인하였으며, EGR(Exhaust Gas Recycling)의 Fouling 현상 가속화에 영향을 미칠 것으로 확인하였다. 본 연구결과물을 토대로 윤활유의 기유, 첨가제, 열화 등에 따른 엔진 및 차량의 성능과 배출가스 특성을 기술정책 자료로서 활용하도록 방향을 도모하고 시험 방법을 확립하고자 한다.

• 생물정신의학
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• 제24권1호
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• pp.19-25
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• 2017

Previous studies have found that firefighters have a tenfold higher prevalence of Parkinson's disease (PD) compare to the general population. Firefighters are constantly exposed to various occupational hazards including toxic chemicals of fire residue and the toxic chemicals can effects development and progression of PD. Nevertheless, there were no studies about the association between exposure to chemical byproducts of combustion and the development of PD among firefighters. Thus the aim of this study is to look into existing researches regarding the effect of chemical byproducts of combustion on the development of PD. An extensive literature search was conducted to identify harmful chemical components of smoke and fire residue, using the PubMed database during November of 2016. We searched for relevant articles by combining several keywords that contained "Parkinson's disease" and each of the different toxic chemicals, yielding a total of 1401 articles. After applying the selection criteria, 12 articles were chosen. Chemical substances reported to have a harmful effect on PD, in at least one article, were carbon monoxide, toluene, manganese and lead. Carbon monoxide and metal substances including manganese and lead were found to be associated with an increased PD risk in more than two articles. There was a heightened risk of PD in firefighters due to exposure of chemical byproducts of combustion including carbon monoxide, toluene, manganese and lead. However, to the best of our knowledge, to support this result we need more systematic epidemiological studies about these risk factors of PD among firefighters. In addition, further studies for the effects of prolonged exposure to toxic fire residue on the development and progression of PD in firefighters are needed.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.715-722
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• 2019

콘크리트 구조물은 외부로부터 콘크리트 내부로 침투 및 확산하는 유해 이온(CO₃^2-, Cl^-, SO₄^2- 등)에 의하여 철근의 부식 및 콘크리트 열화가 발생하여 내구성이 저하된다. 따라서 콘크리트의 열화를 방지 또는 지연시키기 위하여 콘크리트 표면 보호용 마감 모르타르의 사용은 매우 중요하다고 할 수 있다. 본 연구에서는 실리카 졸과 칼슘 이온으로 개질한 천연 라텍스 성분을 열화 콘크리트의 보수용 모르타르 또는 콘크리트 표면 보호용 마감 모르타르에 사용할 수 있는 시멘트 모르타르에 사용함으로써 콘크리트의 열화 방지 또는 열화 지연의 가능성에 대해 검토하였다. 연구 결과, 개질 라텍스 성분 중에 함유된 칼슘 이온과 실리카 졸의 성분에 의해 미세한 칼슘 실리케이트 수화물이 시멘트 재료의 공극에 생성되어 시멘트 모르타르의 공극 분포를 감소시켜 유해 이온(CO₃^2-, Cl^-, SO₄^2- 등)의 침투 및 확산을 저감 시키고, 라텍스 성분이 시멘트 경화체의 공극 내부에 존재함으로 내알칼리성 및 중성화 저항성이 향상됨을 확인할 수 있었다.

• Applied Biological Chemistry
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• 제20권1호
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• pp.117-122
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• 1977

담배에 질산염을 청가하면 질소화합물이 증가되므로 질산염의 대체물(代替物)을 개발(開發)하기위한 실험을 한 결과 다음과 같은 결론을 얻었다. 여러가지 첨가제 중에서 $0.6{\sim}1%$의 시트르산나트륨을 첨가하는 것이 연소성 및 Tar, Nicotine의 감소효과(減少效果)가 가장 양호했다. 특히 조연제첨가(助燃濟添加)에 따른 연소성(燃燒性)과 유해성분감소효과(有害成分減少效果) 및 열특성(熱特性)에 대(對)한 다음과 같은 결과를 얻었다. 1) 연소성이 좋으면 Tar, Nicotine, Bonzpyrene Phenols, NO, $NO_2E, 등의 유해성분이 감소됐다. 2) 단엽에 첨가(添加)된 질산염과 시트르산염의 시차열분석효과(示差熱分析效果)는 시트르산염 첨가시(時) L치(値)가 가장 적고 H치(値)가 가장 컸다. 3) 순수한 질산염과 시트르산염의 시차열분석(示差熱分析)에서 전자는 발열반응(發熱反應)이 없는데 후자는 발열반응(發熱反應)이 있었다. 4) $0.6{\sim}1%$의 시트르산나트륨 첨가시(時)에 Zone A에서는 Tar생성량이 많았고 Zone B에서는 Tar 생성량이 가장 적었다. 또한 이들 담배의 연기에서는 Tar, Nicotine, Phenols, Nitrogen oxides, Benzpyrene의 함량(含量)이 적었으며 연소성이 향상되었다.

• 생명과학회지
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• 제32권12호
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• pp.997-1004
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• 2022

비지박을 포함하는 먹이원을 급이한 흰점박이꽃무지 유충의 영양학적 우수성과 안전성을 검증하고자 비지박 함유 먹이원과 참나무 발효톱밥만으로 사육한 유충의 영양성분과 유해물질을 비교분석하였다. 조단백질 함량은 비지박 함유 먹이원을 급이한 유충(SCC)에서 50.0%로 참나무 발효톱밥으로 사육한 유충(FOS) 44.7%보다 1.1배 많았다. 다량무기질 중 가장 많은 함량을 나타낸 칼륨은 SCC (3169.6 mg/100 g)에서 FOS(1245.9 mg/100 g)보다 2.5배 더 많았다. 미량무기질 중 아연은 SCC (103.0 mg/100 g)에서 FOS (8.2 mg/100 g)보다 12.6배 높은 함량을 나타냈다. 유해물질 분석 결과, SCC와 FOS에서 납, 카드뮴, 비소 모두 식용곤충 중금속 기준에 적합하였고, 병원성 미생물인 대장균과 살모넬라균은 모두 불검출되었다. 위의 연구 결과에 따르면, 비지박을 급이한 흰점박이꽃무지 유충은 다양한 영양성분을 포함하고 있으며, 안전성 또한 검증되었으므로 식용으로 활용하기에 적합할 것으로 판단된다.

• International journal of advanced smart convergence
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• 제4권1호
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• pp.54-63
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• 2015

Increasing air pollution levels and the global oil crisis has become a major hindrance in the growth of our automobile sector. Traditional Internal Combustion engines running on non-renewable fuels are proving to be the major culprit for the harmful effects on environment. With few modifications and also with assistance of few additional components current small SI engines can be modified into a pneumatic engine (commonly known as Compressed Air Engines) without much technical complications where the working fluid is compressed air. The working principle is very basic as adiabatic expansion of the compressed air takes place inside the cylinder pushing the piston downwards creating enough MEP to run the crank shaft at decent RPM. With the assistance of new research and development on pneumatic engines can explore the potential of pneumatic engines as a viable option over IC engines. The paper deals with analysis on RPM variation with corresponding compressed air injection at different crank angles from TDC keeping constant injection time period. Similarly RPM variation can also be observed at different injection pressures with similar injection angle variation. A setup employing a combination of magnetic switch (reed switch), magnets and solenoid valve is used in order to injection timing control. A conclusive data is obtained after detailed analysis of RPM variation that can be employed in newly modified pneumatic engines in order to enhance the running performance. With a number of benefits offered by pneumatic engine over IC engines such as no emissions, better efficiency, low running cost, light weight accompanied by optimized injection conditions can cause a significant development in pneumatic engines without any major alteration.

• 대한영양사협회학술지
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• 제16권1호
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• pp.1-12
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• 2010

This study was conducted to characterize well-being menus and to examine the service frequency and profitability of those served in the contract-managed workplace foodservice. In-depth interviews were conducted with six persons who were in charge of menu management in the headquarters of six different foodservice management companies during March, 2007. In addition, 122 set menus consisting of 777 menu items, which were on one month menus served during January to April, 2007, were collected from three workplace operations managed by three different foodservice management companies. As a result of the in-depth interviews, four categories of well-being menu items were extracted: 'medicinal functional menu item', 'environmentally-friendly menu item', 'natural food menu item', and 'harmful components-limiting menu item'. Accordingly, a well-being menu item was defined as 'a menu item with increased nutrition value or decreased health risk by changing food material or cooking method'. When the menu items (n=777) were analyzed by applying the definition and categories, approximately 14% of the items were identified as well-being menu items and most of them were either medicinal functional (65%) or natural food menu items (33%). Approximately 59% of the 122 set menus included at least one well-being menu item, and therefore they were named the well-being set menus. These well-being set menus, however, were not significantly different from the rest set menus in terms of profitability as measured by the contribution margin. The results of this study could be useful for foodservice management companies to develop and plan well-being menus targeting workplace foodservice operations.

• Journal of Biosystems Engineering
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• 제34권5호
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• pp.315-324
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• 2009

Various types of vibration are transmitted to operators of agricultural tractors while working in the field. Most harmful vibration to human body is ride vibrations with low frequency ranging from 1 to 10 Hz, caused by rough terrain. These ride vibration has vertical and rotational components. This study was conducted to develop an active seat suspension system with two degrees of freedoms, enabling effectively reduce vibrations in vertical and pitch motions. Therefore, a mechanism for the active seat suspension was developed, and an electro-hydraulic servo system and a controller to drive the active seat suspension system were also developed in this study. A simulation model was developed to evaluate how the active seat suspension system effectively reduce the vibrations transmitted to the base of seat. Active seat suspension was optimized to enhance the performance using the developed simulation model. The performance of the seat suspension system was evaluated according to the test codes described in EEC78/764 in order to investigate the feasibility of application to agricultural tractors. The result showed that the developed active seat suspension system could reduce the magnitude of vertical vibration up to 80% for the input vibrations according to the test codes described in EEC78/764. The system could reduce the rotational displacement of ${\pm}\;2.5$ degrees up to 50% for the pitch vibration on the average in the frequency range of 1 to 2 Hz.