• Journal of the Korean GEO-environmental Society
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• v.13 no.5
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• pp.51-57
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• 2012

The purpose of study is to understand the possibility of biogrout of soil induced by bacteria. Microbial Calcium Carbonate Precipitation(MCP) has been analysed using the microorganism Bacillus Pasteurii. In order to understand the biogrout of soft ground treated with microbial calcium carbonate precipitation, four types of specimens(sterilization soil, non-sterilization soil, reaction solution and microorganism solution with pre-treatment mix and reaction solution and microorganism solution with post-treatment mix) were made. Scanning Electron Microscope(SEM), EDX and X-ray diffraction(XRD) analyses were performed on the soft ground specimens. On the basis of the preliminary results, it appears that microbial treatment methods using calcium carbonate precipitation may be possible to improve property of biogrout.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.429-436
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• 2003

This paper presents a new approach for evaluating the transmission marginal loss factors (MLFs) considering the reactive power. Generally, MLFs are represented as the sensitivity of transmission losses, which is computed from the change of the generation at reference bus by the change of the load at the arbitrary bus-i. The conventional evaluation method for MLFs uses the only H matrix, which is a part of jacobian matrix. Therefore, the MLFs computed by the existing method, don't consider the effect of the reactive power, although the transmission losses are a function of the reactive power as well as the active power. To compensate the limits of the existing method for evaluating MLFs, the power factor at the bus-i is introduced for reflecting the effect of the reactive power in the evaluation method of the MLFs. Also, MLFs calculated by the developed method are applied to energy spot markets to reflect the impacts of reactive power. This method is tested with the sample system with 5-bus, and analyzed how much MLFs have an effect on the bidding/offer price, market clearing price(MCP), and settlement in the competitive energy spot market. This paper compared the results of MLFs calculated by the existing and proposed method for the IEEE 14-bus system, and the KEPCO system.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.116-125
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• 1998

Most of modern mobile communication systems require low distortion in addition to high power and high efficiency characteristics for power amplifiers. The power amplifiers cause adjacent channel interference by intermodulation and spectral regrowth. In order to analyze the effects of the power amplifier on communication system, a 22Mcps spreaded digital modulated signal source and a ISM band power amplifier have been constructed, ACPR characteristics are simulated and measured for the RZ and NRZ encoded signals.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.1-8
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• 2007

The ultra-fine tungsten carbide(WC) powders have been actively used in the cemented carbides industry, because they have excellent mechanical properties such as high hardness, strength, and toughness. In this study, ultra-fine WC-Co alloys powders have been fabricated by thermochemical and thermomechanical process such as spray conversion process or high energy ball milling. The non-coated end-mill which is made of ultra-fine tungsten carbide is investigated by measuring cutting force, tool wear, tool life, and surface roughness profile according to cutting length. The machining test was conducted with high hardened workpiece and their performances are investigated in high speed cutting conditions. Also, the relationship between the machining characteristics and the Co contents are investigated under various high speed cutting conditions.

• The Korean Journal of Ecology
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• v.28 no.6
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• pp.395-404
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• 2005

A project has recently begun to reintroduce endangered Asiatic black bears to the Jirisan National Park. However, information on home range that is necessary to maintain the Minimum Viable Population (MVP) of those bears does not exist. Based on point data of two bears that were released for trial in Jirisan in 2001, we identified the movement pattern of bears and estimated their home ranges with two different methods Finally, the possibility of conserving the MVP of bears was evaluated by comparing the location and size of the home range with habitats which have been found to be suitable for bears. The frequency of bears' appearance reduced drastically as road densities of both paved roads and legal trails increased. The midpoint of home ranges of the two bears was 376.85 $km^2$ and 50.76 $km^2$ based on 100% MCP (Minimum Convex Polygon) and 95% AK (Adaptive Kernel Home Range Method), respectively, with an overlapped area of 126.0 $km^2$ and 3.99 $km^2$ each. The core areas of their home ranges are located not in the no-entry zone, where major trails were open to the public - despite being designated as no -entry zone - but in areas where most trails were closed to the public. A discrepancy between core areas of home ranges and potentially suitable habitats suggests the effects of vehicles and tracking people through roads within the park. Thus, for the success of in situ conservation of endangered bears, well-planned management of habitats is needed to protect bears and to ensure the home ranges to support the MVP.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.11a
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• pp.36-36
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• 2002

최근 한국기계연구원에서 개발된 Mechanochemical process (MCP)는 Spray conversion 법에 의하여 나노크기의 W/Cu 복합 분말을 제조하는 방법으로서, 현재 (주)나노테크에서 산업화를 위한 시험/개발이 진행 중이다. 이 방법에 의하여 W /1 0 ~ 40wt. %Cu 조성의 초미렵 W/Cu 복합 분말의 양산화가 가능하게 됨으로써, 나노복합분말을 사용한 초미립 W/Cu 합금의 소결 제조 연구 역시 나 노태크에서 분말사업화와 동시에 수행되고 있다. 현재 Spray conversion 법으로 제조되고 있는 W/Cu 나노복합분말 및 그 소결체는 Cu의 조성범 위에 따라 민수용 및 군수용 제품으로의 적용이 시도되고 있으며, 각기 특성향상을 목표로 각 적용 분야에서 요구되는 제반 성능에 대한 검토가 이루어지고 있다. 특히 군수용의 목적으로 사용될 경우, 정적 및 동적부하상태에서 재료의 균일한 변형이 가장 중요한 특성이다. 현 개발품의 경우, 일반 W 빛 Cu 원료에 비하여 상대적으로 높은 순도의 원료를 사용하였기 때문에 분말 및 소재상태 에서의 순도가 높아서, 연성을 저하시키는 것으로 알려진 기지상내 합금원소 또는 interface 게재물 이 존재할 가능성이 매우 낮다. 또한 초미립 W 입자들과 Cu 상의 혼합도가 극대화된 상태이기 때문에 상대적으로 저옹에서도 완전치밀화된 미세조직을 얻을 수 있는데, 이는 분말상태의 균일한 미세구조를 유지할 수 있으며, 동시에 W 업자간의 과도한 neck 형성을 방지함으로써 기계적 변형시 재료의 연성 향상이 기대된다. 이러한 W/Cu 나노복합분말 소결체의 특성은 균일한 밀도분포와 동시에 과도한 동적 부하상태에서 균일한 변형이 보장되어야만 하는 특정 군수용 목적에 잘 부합하는 것으로 판단된다. 본 고에서는 상기한 W/Cu 나노복함분말을 사용하여 균일한 미세구조를 가지는 완전치밀화된 소결재를 제조하는 과정과 제조된 소결재를 향후 군수용 제품에 척용시키기 위하여 진행된 단조특성에 대한 연구결과틀을 재료의 미세구조척 관점에서 논의하였다.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.497-502
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• 2011

Broccoli is considered as one of the functional foods to offer a hearty supply of the nutrient-rich vegetable in the world. Broccoli contains high level of phytochemicals, and that is selected as one of the top 10 vegetables for human health promotion. Especially, glucosinolates and flavonoids are well known as anti free oxygen radicals in vegetables and fruits. In Korea, broccoli consumption has increased to well known on the health-beneficial vegetables since 2000. However, broccoli has many problems of postharvest management since the quality of harvested heads quickly declines. Major problems are the floret yellowing, wilting, off-odor, and decay. The multiple postharvest applications improve broccoli quality and cold treatment including pre-cooling extends on the shelf-life with circumstance of optimum storage which is 0℃ temperature and a range of 95-100% relative humidity. Controlled atmosphere or modified atmosphere packaging can be used as supplemental treatments to extend postharvest life. 1-2% O₂ + 5-10% CO₂ is currently recommended for broccoli. Postharvest management is important for broccoli because price fluctuations depend on harvest time and quality. In this study, we tried to review physiological change of broccoli after the harvest, storage method, and various techniques to optimize quality during distribution.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.6
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• pp.264-270
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• 2017

In this study, while the abrasive plates for diamond have been prepared through mechanical alloying and sintering of elemental powders, a fabrication route of plasma thermal coatings has been adopted for the first time. When diamond knife is sharped or polished, a metal plate has been applied, which is made of mechanical alloying and sintering. In this study, in order to develop a cost - effective manufacturing process, plasma coatings of FeCrNi and Ti on cast iron plate were applied together with Al intermediate layer coatings. The plasma coatings were successfully performed, and the optimum coating layer conditions were discussed in terms of micro-structural observations at the interfaces.

• Korean Journal of Environment and Ecology
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• v.22 no.3
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• pp.230-240
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• 2008

The primary aim of this study is to estimate the home range of a pair of raccoon dogs(Nyctereutes procyonoides koreensis) and to compare with the previous study of raccoon dogs in a rural area of Gurye, the southern part of South Korea. Radiotracking was regularly carried out on 2 raccoon dogs for 2 days every 2 months(in June, August, October and December, 2006). During the 2 days, radiotracking was usually conducted every $1{\sim}3$ hours through day and night. The analysis of tracking data with a total of $46{\sim}64$ bearings showed that the total home range size of the pair was $0.41km^2$, and mean home range size was $0.32km^2$ by 95% minimum convex polygons(MCP) estimate. The home ranges of the male and female were largely overlapping(about $70{\sim}95%$), and the sizes were not very much different from each other. However, there was a big difference between day $(0.01km^2)$ and night-time $(0.35km^2)$ home ranges, and it was largest in summer$(0.56km^2)$ and smallest in winter $(<0.01km^2)$. In addition, the home range of the pair included 1 core area and 4 different feeding areas. In conclusion, our raccoon dog home range data using the same individuals but with more frequent bearings per day and more extended tracking intervals still showed very similar results to the previous study with less frequent bearings per day and more extensive tracking days.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.2
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• pp.178-189
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• 2003

Purpose: The current study was designed to investigate the expression pattern of chemokine in musculoskeletal tumors, and between primary osteosarcoma and recurred, and postchemotherapy one. Materials and methods: Ten primary soft tissue and bone tumors, one primary, one recurred, one post-chemotherapy osteosarcoma, and one normal control patients were included in the current study. RT-PCR and RPA were used for the investigation of the expression of cytokines and chemokines. Fisher's exact test in SPSS was used for the statistical analysis. Results: IL-8 and TNF-${\alpha}$ were expressed in all tumor tissues, IFN-${\gamma}$ was in all except two cases, RANTES was in 5 soft tissue tumors and 4 bone tumors, GRO-${\alpha}$was in one soft tissue tumor and 2 bone tumors, and MCP-1 and IP-10 were in two bone tumors and in all the other group. In recurred osteosarcoma all the cytokines and chemokines were expressed, and the degree of the expression was stronger than the primary, except IFN-${\gamma}$. After chemotherapy, RANTES, IFN-${\beta}$ and TGF${\beta}_1$ among the TGF${\beta}$isoforms were expressed. Conclusion: There were differences in the expression of cytokines and chemokines in some different bone and soft tissue tumors, even though it was impossible to support this statistically due to small numbers of cases. The expression pattern of IFN-${\gamma}$and TGF-${\beta}$ isoform in osteosarcoma could be used for the study of tumor recurrence and the changes after chemotherapy.