This study focuses on fabricating silver flake powder by a mechanical milling process and investigating the formation of flake-shaped particles during milling. The silver flake powder is fabricated by varying the mechanical milling parameters such as the amount of powder, ball size, impeller rotation speed, and milling time of the attrition ballmill. The particle size of the silver flake powder decreases with increasing amount of powder; however, it increases with increasing impeller rotation speed. The change in the particle size of the silver flake powder is analyzed based on elastic collision between the balls, taking energy loss of the balls due to the powder into consideration. The change in the particle size of the silver flake powder with mechanical milling parameters is consistent with the change in the diameter of the elastic deformation contact area of the ball, due to the collision between the balls, with milling parameters. The flake-shaped silver particles are formed at the elastic deformation contact area of the ball due to the collision. Keywords: Flake powder, Milling, Ball collision, Elastic deformation

This study is focused on investigating the relation between the particle size of silver flake powder and mechanical milling parameters. Mechanical milling parameters such as ball size, impeller rotation speed and milling time of the attrition ball-mill were controlled to produce silver flake powder. The particle size of the silver flake powder increased with increasing ball size and impeller rotation speed. The change of the particle size of the silver flake powder with mechanical milling parameters was analyzed based on balls motion in the mill container of the attrition ball-mill. The silver flake particles were formed at the elastic deformation area of the ball due to the collision between balls. The change of the particle size of the silver flake powder with mechanical milling parameters well consists with the change of the collision energy of ball with parameters mentioned above.

The antimutagenic effects of 46 kinds of medicinal plants that have been used as traditional folk antitumor agents in Korea were studied by using Ames mutagenicity teat. Most of the methanolic extracts from the plants which were used in this experiment showed strong antimutagenic activity toward atlatoxin B₁(AFB₁) in Salmonella typhimurium TA100 and TA98. However, N-methyl-N'-vitro-N-nitrosoguanidine (MNNG) induced mutagenicity was not blocked by adding the methanolic extracts of the plants except persimmon leaves (Diospyros kaki Thunberg) and Elaeagnus umbellata.

본 연구는 식물자원을 재료로 하여 in vitro 항염증 및 항산화 활성을 분석함으로써 기능성소재로의 활용 가능성이 있는 유망 후보자원을 발굴하고자 수행하였다. 이를 위해 식물추출물 38종을 대상으로 세포증식에 대한 영향, 염증 관련지표(nitric oxide, TNF-α, IL-6, IkBα, iNOS, COX-2) 및 항산화항목(DPPH 라디칼 소거능, LDL 산화저해능) 및 총페놀 함량에 대한 효과를 탐색하고 결과로부터 8종의 시료를 1차로 선발하였다. 선발된 8종의 시료에 대해서는 다시 농도별로 세포증식에 대한 효과, iNOS, COX-2의 발현 및 NF-kB 전사에 대한 영향, peroxynitrite, ROS, nitric oxide 생성에 대한 IC50 값을 분석하여 보다 가능성이 있는 식물을 유망후보자원으로 선발하고자 하였다. 그 결과, 소사나무(가지), 등골나물(잎), 으름(꽃) 및 개모시풀(뿌리)은 항염증 혹은 항산화활성이 우수하나 농도에 따라 세포독성을 나타내었으므로 활용에 주의가 필요해보였으며, 어저귀(잎)은 항염증활성과 항산화활성이 비교적 우수하고 실험된 처리농도에서 세포독성이 없어 향후 in vivo 활성 검정 등 심화연구를 통해 그 활용 가능성을 검토할 필요가 있다고 사료되었다.

Establishment of emission concentrations of PCDDs and PCDFs in emission gases from 85 domestic crematories were measured. The relationship between PCDDs/DFs and several factors such as structure, equipment and operational state of the crematory is discussed. Furthermore, emission of PCDDs/DFs from all crematories in korea is estimated. The following results are obtained: (1) total concentration (2,3,7,8- substituted isomers) of PCDDs/DFs was 0.113 ~ 14.34 ng/ Sm3, whose TEQ concentration was 1.815 ng-TEQ/Sm3; (2) total emission of PCDDs/DFs from crematories in korea was estimated to be 1.815 g-TEQ/yr.

Infectious diseases in domestic animals of carcase were increasing every year. According to the monthly report for infectious disease from Ministry for Food, Agriculture, Forestry and Fisheries, 11,954 heads of cattle, 518,178 heads of pig, 232,850,244 heads of bird were reported in 2011. Infectious diseases of carcase almost spread on a national scale. Dead or emergency preventive carcase are completely treated on bury. Since the treatment of carcase on bury are generating soil, underground water and source water pollution, introduction of new preventive system should be considered. In this study, literature survey and case studies to prevent the spreading of virus for infectious disease and second environmental pollution were investigated. The actual experiments using the existing incineration facilities were also performed to ensure the possibilities of safe treatment of carcase. On the other hand, the moving-type incineration are also being developed and its operation manual will be prepared. Among the investigated incinerators, stoker type incinerator was not suitable for the treatment of carcase, however, other incinerators such as fluidized-bed type incinerator, rotary kiln type incinerator ware shown to be suitable. But even for the stoker type incinerator, if the pre-treatment facilities( grinding, crushing) are installed, it will also be a suitable method. The analytical results for air pollutants(including dioxin) emitted from the final exit were all satisfied to the air pollution emission standards.

In this study, PCDDs/DFs concentrations in flue gases from 58 crematories and in fly ashes and bottom ashes (mainly bone) from several crematories were measured to grasp the present state of PCDDs/DFs emissions from crematories. The effects of several factors were discussed to prevent PCDDs/DFs emissions from crematories. Total concentration of PCDDs/DFs was ranged from 0.113 to 87.461 ng/Sm3 and toxic equivalent concentration was ranged from 0.019 to 15.347 ng-TEQ/Sm3. As the results obtained in this research, the following measures to reduce PCDDs/DFs emission are recommended for existing crematories: (1) keeping the temperature at < 800oC or < 850oC in main/secondary chambers during a whole cremation, (2) lowering the temperature in the dust collector, (3) installing the high efficiency dust collector and reducing dust concentration to less than 0.02 g/Sm3, and (4) installing the sampling point for monitoring of PCDDs/DFs.

Establishment of emission standard of dioxins from crematories has been needed for their efficient management in korea. In this study, we investigate related regulation, guideline and management of crematory at home and abroad. Either dioxin legal basis or management of countries are compared and analyzed respectively. Crematories were distributed 51 place all over the country and total 265 crematories have been operated in 2000. Korea crematories have been operated 3 steps; incineration, cooling in furnace and collection of bone. This process is similar with Japanese process. But European process is different steps; incineration, keeping the temperature of furnace and collection of bone. In case of Korea, the resynthesis of dioxins in the cooling process due to the dioxin emissions higher than European process. This study has suggested three emission standards of dioxins from crematories based on survey of foreign standards and korean measurement data. The 1st suggested standard is 10 ng-TEQ/Sm3 in present facility, 5 ng-TEQ/Sm3 in new facility, the 2nd suggestion is 5 ng-TEQ/Sm3 in present facility, 1 ng-TEQ/Sm3 in new facility and the 3nd suggestion is 0.5 ng-TEQ/Sm3 in present facility, 0.1 ng-TEQ/Sm3 in new facility. When 2nd suggestion apply, at 2020 dioxin emissions(0.779 g-TEQ/yr) is expected to be approximately 71% reduction compared to 2010 year.

As increasing incidents of FMD (Foot and Mouth Disease) in recent years, the country has struggled with huge economic losses and environmental problems. Because of relying only on the burial method according to domestic condition, it needs to consider the alternative measure such as the incineration with being no secondary environmental pollution. In addition, such FMD and AI (Avian Influenza) as classifying in the first-class malignant diseases are very important to be ready with rapidly initial response because of the fact being quickly spreaded with high infection speed. Accordingly, a favorable initial response by the introduction of mobile incinerators has been forced to consider. In this study, it analyzed and compared the existing disposal regulations and methods of carcasses to establish the reasonableness about introducing an incineration technology. In addition, domestic and international disposal status was compared as investigating regulations or disposal law, guidelines of livestock in major developed countries. To introduce the mobile incineration facilities in domestic, it is surveyed international examples and related regulations of using and developing mobile incinerators. The results of study could be used as basic information to design and utilize a mobile incineration process for slaughter animals by deceases.