• 한국농공학회논문집
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• 제65권1호
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• pp.51-59
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• 2023

The study is to evaluate the effect of bank protection concrete block products to streams and soils. The effect on three types of bank protection concrete blocks was evaluated.. The first type was manufactured using fly ash, and the second and third type products used fine blast furnace slag powder. The laboratory and field Experiments test results showed the pHs of 9 or less. Also, any heavy metals were not detected in the heavy metal leaching tests. Although some iron (Fe) was partially detected, it still met the water quality standards. In addition, heavy metal was detected from all blocks by the US drinking water evaluation standards method. An on-site water quality and soil contamination tests were performed at the places that the blocks were implemented in practice. The test results showed that the application of the bank protection concrete block product did not lead to the water and soil quality degradation. Therefore, it was found that the hardened bank protection concrete block product did not elute harmful substances such as heavy metals that affect water and soil quality degradation.

• 상하수도학회지
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• 제28권4호
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• pp.441-451
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• 2014

The flushing is important to maintain good water quality in water main. It is a technique of using water velocity to remove sediments in water distribution system. The variety of water quality problems can occur in a distribution system, so too can a variety of benefits be gained by system flushing. In order to effectively perform the flushing, the contaminants to be removed to set up and it can be solved, it is necessary to ensure the proper flow rate. In this study, the removal of contaminants present in the inner water pipe attached loose deposits such as fine particles of granular activated carbon, sand and iron corrosion product sought to derive flow rates. Thus, the constant observation of using pilot plant scale water distribution plant for the movement of floating characteristics of particles were assessed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.514-519
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• 2001

Converter has been slag produced 10 million tons per year in Japan. It is a steel making by product produced in the same way as the blast-furnace slag. Though blast-furnace slag is being used effectively as a concrete admixture, the converter stag has never been used effectively because of the expansion action of contained free lime and iron oxide. This is an important environmental problem in the steel industry. Beta-2CaOSiO$_2$(beta-C$_2$S) is contained 40 percent in converter slag, therefore it is very promising as a concrete admixture. We proposed an accelerated aging processes capable of stabilizing the converter slag in a short time. The converter slag is dipped into alkali aqueous solution after heating at low temperature. It was subsequently ground to a grain size of 75 ${\mu}{\textrm}{m}$ , inner 30 percent of OPC. The properties of mortar and concrete using the blended cement were determined. As a result, it has become apparent that the expansion was reduced and long term compressive strength was increased while that at early ages was not so remarkable. The hydration exotherm rate was lower than that of the OPC.

• 대한전기학회논문지
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• 제39권11호
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• pp.1174-1182
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• 1990

A hgih efficiency and good dynamic performance drive system of an induction motor is presented in this paper using vector control technique. If the induction motor is driven under light loads with rated flux, the iron loss is excessively large compared with the copper loss, resulting in poor motor efficiency. High efficiency drive of an induction motor can be achieved by adjusting the flux level which leads the total motor loss to be a minimum value. Generally reducing the flux degrades the dynamic performance, but the dynamic performance of the proposed system is also maintained high. If the d-axis is coincident with rotor flux phasor in synchronous rotating reference frame, the stator current can be decoupled as flux component and torque component. At steady state, the developed motor torque is proportional to the product of the flux and torque component. The combination of the two components minimizing the motor loss could be found with numerical method. As the procedure to obtain the optimal combination is too hard, it is found experimentally. The system block diagram is suggested for maximum efficiency control. The proposed system is studied through digital simulation and verified with experiment. The experimental results show the possiblity of a high efficiency drive with good dynamic performance of maximum efficiency control.

• 한국분말재료학회지
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• 제23권6호
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• pp.447-452
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• 2016

Neodymium-iron-boron (Nd-Fe-B) sintered magnets have excellent magnetic properties such as the remanence, coercive force, and the maximum energy product compared to other hard magnetic materials. The coercive force of Nd-Fe-B sintered magnets is improved by the addition of heavy rare earth elements such as dysprosium and terbium instead of neodymium. Then, the magnetocrystalline anisotropy of Nd-Fe-B sintered magnets increases. However, additional elements have increased the production cost of Nd-Fe-B sintered magnets. Hence, a study on the control of the microstructure of Nd-Fe-B magnets is being conducted. As the coercive force of magnets improves, the grain size of the $Nd_2Fe_{14}B$ grain is close to 300 nm because they are nucleation-type magnets. In this study, fine particles of Nd-Fe-B are prepared with various grinding energies in the pulverization process used for preparing sintered magnets, and the microstructure and magnetic properties of the magnets are investigated.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권2호
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• pp.94-99
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• 2008

The replica of silicone mold which can produce the test samples and the market-displayable products without making expensive metallic patterns is advantageous because it incurs less cost than the ordinary method that manufactures the products from the metallic patterns. However, the production of the products using silicone mold should require a technician with professional knowledge about the metallic patterns every time. Thus we tried to judge whether a forming analysis software for iron molding can be applied to silicon molding in this paper. In other words, this paper suggests a method to use a computer simulator from the designing step of the silicone mold, which is the most important part in making replica using simple silicone molds to the step of pouring the cast. The paper shows that if the know-how of a professional worker is provided in advance, an amateur worker can easily produce silicone molds of the best quality, the defective rate of the products will be decreased, and the replica will have a more complete status. By doing so, we suggested a possibility for reducing the delivery time at the production sites and for improving the product quality.

• 방사성폐기물학회지
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• 제19권2호
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• pp.233-241
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• 2021

A series of three bench-scale experiments was performed to investigate the conversion of sodium metal to sodium chloride via reactions with non-metal and metal chlorides. Specifically, batches of molten sodium metal were separately contacted with ammonium chloride and ferrous chloride to form sodium chloride in both cases along with iron in the latter case. Additional ferrous chloride was added to two of the three batches to form low melting point consolidated mixtures of sodium chloride and ferrous chloride, whereas consolidation of a sodium-chloride product was performed in a separate batch. Samples of the products were characterized via X-ray diffraction to identify attendant compounds. The reaction of sodium metal with metered ammonium chloride particulate feeds proceeded without reaction excursions and produced pure colorless sodium chloride. The reaction of sodium metal with ferrous chloride yielded occasional reaction excursions as evidenced by temperature spikes and fuming ferrous chloride, producing a dark salt-metal mixture. This investigation into a method for controlled conversion of sodium metal to sodium chloride is particularly applicable to sodium containing elevated levels of radioactivity-including bond sodium from nuclear fuels-in remote-handled inert-atmosphere environments.

• Animal Bioscience
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• 제35권8호
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• pp.1279-1288
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• 2022

Objective: The aim of this study was to investigate antioxidant activities of cinnamon (Cinnamomum cassia) extracts (extracted with different solvents) at various concentrations and to determine product quality of raw chicken patties added with different levels of cinnamon powder (CP) and oyster mushroon powder (OMP) during storage. Methods: After cinnamon was made into oven dried CP and extracted with water and different levels (50%, 80%, and 100%) of ethanol, antioxidant activities of these extracts were determined. CP and OMP were combined at different levels and added to raw chicken patties. Physicochemical properties and microbial counts were measured during refrigerated storage. Results: Cinnamon ethanol (80%) extract showed the highest (p<0.05) by 2,2-diphenyl-1picrylhydrazyl-radical scavenging activity and reducing power. Cinnamon water extract (CWE) had the highest iron chelating ability (p<0.05), while CP 100% ethanol extract had the highest content of total phenolic compound. Then, CP and OMP were applied to chicken patties at different levels (0.1% to 0.2%). After the addition of CPs, pH, L* (lightness), 2-thiobarbituric acid reactive substance, and volatile basic nitrogen values were decreased, whereas a* (redness) and b* (yellowness) values were increased. Microbial counts of total bacteria and Enterobacteriaceace were decreased with the addition of CP 0.2% regardless of the OMP level. Conclusion: The addition of CP in combination with OMP can increase the shelf-life of chicken patties during storage.

• Design & Manufacturing
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• 제16권3호
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• pp.16-21
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• 2022

In order to reduce the weight of parts and materials for the development of high-efficiency engines in accordance with the strengthening of automobile fuel efficiency regulations, the existing casting material is changed to a iron plate material, and plastic processing and turning operations are performed to lighten the weight and reduce the manufacturing cost. Among the pulley components applied to the damper pulley, the HUB product was manufactured by plastic machining instead of the existing casting process, and the inspection standardized for automating the inner diameter and parallelism measurement of the turning result of the new hub part with improved quality, and the inspection system for this Development of design and operation software to automate the inspection of the inner diameter and parallelism of the hub was described. The representative specifications of the development equipment are a hub inner diameter 22mm inspection system, a three-point inspection system with a parallelism of 0.15mm on the top.

• 대한화학회지
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• 제37권2호
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• pp.228-236
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• 1993

Grignard 시약,CH_3$MgI와 브로모벤질과의 반응은 전자전달과정(SET)과 라디칼 이온쌍 중간체를 거쳐 생성되는 동종짝지음 생성물 bibenzyl을 주생성물로 이온성 공격에 의해 생성되는 교차짝지음 생성물, 에틸벤젠을 부생성물로 생성시키며 전이금속 불순물이 거의 제거된 순수 금속 Mg으로 CH_3$MgI을 제조하였을 때 그 비는 78:22이었다. 그러나 실험실용 금속 Mg을 사용하였을 때 그 비는 감소하여 67:33이었으며 이 비는 촉매량으로 첨가시킨 $FeCl_3$ 양의 증가로 더욱 감소되어 최고 20:80 비로 Fe 이온은 이온성 교차생성물, 에틸벤젠을 주생성물로 유도하였으며 이러한 반응결과는 좋은 수소원자주게로 디이소프로필 에테르를 디에틸 에테르 대신 용매를 사용하였을 때에도 큰 변화가 관찰되지 않았다. 이러한 관찰은 Grignard 시약과 유기할로겐 화합물이나 카르보닐 화합물과의 반응에서 촉매 양의 전이금속염이 전자전달과정 속도를 증가시켜 동종짝지음 이합체 생성물의 증가를 일으키는 보고와 반대의 경향을 보인다. 이러한 촉매량의 $FeCl_3$ 첨가가 CH_3$MgI의 이온성 공격의 증가와 그에 따른 교차짝지음 생성물의 증가로 유도하는 것은 브로모벤질과 반응 중 생성된 Fe 종과의 착화합물 형성에 의해 벤질탄소-브롬 결합이 CH_3$MgI의 탄소음이온 공격에 대해 반응성이 증가되는 것으로 설명하였다. 이러한 설명은 2-페닐-1-브로모에탄의 CH_3$MgI와의 반응연구에서 관찰된 반응성 결여가 뒷받침하고 있다.