• Membrane and Water Treatment
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• 제11권3호
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• pp.231-235
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• 2020

Industrialization and modern developments have led to an influx of toxic heavy metals into the aquatic environment, and the accumulation of heavy metals has serious adverse effects on humans. Among the various heavy metal treatment methods, adsorption is very useful and frequently used. Plastic materials, such as polypropylene and polyethylene, have been widely used as filter media due to their mechanical and chemical stability. However, the surface of plastic material is inert and therefore the adsorption capability of heavy metals is very limited. In this study, granular media and fiber media composed of polypropylene and polyethylene are used, and the surface modification was conducted in order to increase adsorption capability toward heavy metals. Oxygen plasma generated hydroxyl groups on the surface of the media to activate the surface, and then acrylic acid was synthesized on the surface. The grafted carboxyl group was confirmed by FT-IR and SEM. Heavy metal adsorption capability of pristine and surface modified adsorbents was also evaluated. Overall, heavy metal adsorption capability was increased by surface modification due to electrostatic interaction between the carboxyl groups and heavy metal ions. Fibrous PP/PE showed lower improvement compared to granular PP media because pore blockage occurred by the surface modification step, thereby inhibiting mass transfer.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.777-783
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• 2001

This paper is mainly concerned with the state of the practical developments of a constants PWM bridge type resonants DC-DC suitable converter for Nd:YAG Laser with a Microprocessor. (PIC16C54 & 8051) The use of IGBT power supply with feedback control of flashLamp currents imparts a advantages to Nd:YAG Laser for materials processing. these include the alility to tailor the pulseshape and modify pulse parameters on a pulse- by pulse basis. And Correct choice of pulseshape can enhance the repeatability of the process. as higher power IGBT became available, act ive pulseforming power supplies will find greater user in deep hole drilling machine By Using certain control tecniques, utililized in designing Pic16c54 from Microchip technology and Intel 8051, also Mornitoring from Microsoft Visual Basic 5, And it allowed us to designed and fabricate ahigh repel it ion rate and high power(HRHP) pulsed Nd:YAG laser system, As a result of that, the current pulsewidth could be contort led 200s to 350s(step 50s) , and the pulse repetition rate could be adjusted 500pps to 1150pps. In addition, in the case of one laser head consisting of a Nd:YAG laser rod and two flashlamps , the maximum laser output of 240w was produced at the condition of 350s and 1150pps, and that of about 480w was generated at the same condition when two laser heads were arranged in cascade.

• 한국토양비료학회지
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• 제45권1호
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• pp.118-126
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• 2012

Korea's agriculture had many inherent problems. Korea is a mountainous country with only 22 percent farmland and less rainfall than most other neighboring rice-growing countries. A major land reform in the late 1940s and early 1950s spread ownership of land to the rural peasantry. Individual holdings, however, were too small or too spread out to provide families with much chance to produce a significant quantity of food. The enormous growth of urban areas led to a rapid decrease of available farmland, while at the same time population increases and bigger incomes meant that the demand for food greatly outstripped supply. The result of these developments was that by the late 1980s roughly half of Korea's needs, mainly wheat and animal feed corn, was imported. Korea's agriculture is facing a new round of difficulties from the inevitable process of market opening. Therefore, we have reviewed the agricultural status and soils in Korea how we can meet the coming issues with respect to production and prospect based on the government documents and articles published on the journals.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.448-452
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• 2007

Many industrial operations require continuous or nearly-continuous operation of machines, which if interrupted can result in significant financial loss. The condition monitoring of these machines has received considerable attention recent years. Rapid developments in semiconductor, computing, and communication with a remote site have led to a new generation of sensor called "smart" sensors which are capable of wireless communication with a remote site. The purpose of this research is the development of smart sensor using which can on-line perform condition monitoring. This system is addressed to detect conditions that may lead to equipment failure when it is running. Moreover it will reduce condition monitoring expense using low cost MEMS accelerometer. This sensor can receive data in real-time or periodic time from MEMS accelerometer. Furthermore, this system is capable for signal preprocessing task (High Pass Filter, Low Pass Filter and Gain Amplifier) and analog to digital converter (A/D) which is controlled by CPU. A/D converter that converts 10bit digital data is used. This sensor communicates with a remote site PC using TCP/IP protocols. Wireless LAN contain IEEE 802.11i-PSK or WPA (PSK, TKIP) encryption. Developed sensor executes performance tests for data acquisition accuracy estimations.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2007년도 추계 종합학술대회 논문집
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• pp.478-481
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• 2007

생체물질인 단백질은 질병과 직접적인 관련이 있어 현대 의약품의 혁신분야로 주목받고 있다. 생명공학기술의 발달을 기반으로 생체 내에 미량 존재해 실용화하기 어려웠던 생리활성 단백질의 대량 생산을 유전자 재조합 기술을 통해 가능케 함으로써 단백질 치료제로서 실용화되고 있다. 단백질 의약품은 종양계, 면역계, 유전질환 관련 제품이 괄목할 만한 성장을 보이고 있다. 세계 제약시장의 주력이 기존의 화학합성 의약품에서 바이오 의약품으로 빠르게 전환되고 있고, 그 중 대부분을 의약용 단백질이 차지할 전망이다. 최근 단백질 의약품의 바이오제네릭 시장이 유망한 시장으로 떠오르고 있고, 경쟁도 격화되고 있다. 본 연구에서는 이러한 상황에 대응하기 위하여 산업분석을 통한 단백질 사업화 전략을 제안한다.

• East Asian mathematical journal
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• 제28권2호
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• pp.215-232
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• 2012

The methods of selection through observations and recommendations were introduced in the process of recruiting new students for the science education institutes for the gifted attached to 25 universities recently. This paper itemized the methods of screening through observations and recommendations. This paper also analyzed the problems with the methods and attempted to create plans for their improvement. The methods of selection through observations and recommendations led to the positive results that students' usual activities and attitudes in the classroom were reflected on the evaluation and that the cost of their private lessons was also reduced. However, the methods showed a few problems that need to be corrected. We point out problems occurring with examining their documents for submission and interviews. It was not easy to grade candidates' gifts, creativity, potential and development within the contents of the documents and the limited time of conducting interviews. On the plans for the developments of the implemented methods of selection through observations and recommendations, we have several suggestions. The chances for teachers' in-service training of learning the methods of selection through observations and recommendations need to be expanded. The interview needs to be enhanced and to have the same weight as the document screening. To secure the continuity of the education for the gifted, the clear guidelines from the Ministry of Education, Science, Technology along with the cooperation of the education institutes for the gifted are essential.

• Journal of Electrochemical Science and Technology
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• 제11권3호
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• pp.220-237
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• 2020

Modern electrochemical energy devices involve generation and reduction of fuel gases through electrochemical reactions of water splitting, alcohol oxidation, oxygen reduction, etc. Initially, these processes were executed in the presence of noble metal-based catalyst that showed low overpotential and high current density. However, its high cost, unavailability, corrosion and related toxicity limited its application. The search for alternative with high stability, durability, and efficiency led scientists towards carbon nanoparticles supported catalysts which has high surface area, good electrical conductivity, tunable morphology, low cost, ease of synthesis and stability. Carbon nanoparticles are classified into two groups based on morphology, one and zero dimensional particles. Carbon nanoparticles at zero dimension, denoted as carbon dots, are less used carbon support compared to other forms. However, recently carbon dots with improved electronic properties have become popular as catalyst as well as catalyst support. This review focused on the recent advances in electrocatalytic activities of carbon dots. The mechanisms of common electrocatalytic reactions and the role of the catalysts are also discussed. The review also proposed future developments and other research directions to overcome current limitations.

• 한국소음진동공학회논문집
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• 제18권8호
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• pp.872-878
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• 2008

Many industrial operations require continuous or nearly-continuous operation of machines, interruption of which can result in significant cost loss. The condition monitoring of these machines has received considerable attentions in recent years. Rapid developments in semiconductor, computing, and communication with a remote site have led to a new generation of sensor called "smart" sensors which are capable of wireless communication with a remote site. The purpose of this research is to develop a new type of smart sensor for on-line condition monitoring. This system is addressed to detect conditions that may lead to equipment failure when it is running. Moreover it will reduce condition monitoring expense using low cost MEMS accelerometer. This system is capable for signal preprocessing task and analog to digital converter which is controlled by CPU. This sensor communicates with a remote site PC using TCP/IP protocols. The developed sensor executes performance tests for data acquisition accuracy estimations.

• 전기학회논문지P
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• 제67권2호
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• pp.112-118
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• 2018

In recent years, decentralized power have been increasing due to environmental problems, liberalization of electricity markets and technological developments. These changes have led to the evolution of power generation, transmission, and distribution into discrete sectors and the division of integrated power systems. Therefore, studies are underway to efficiently supply power and reduce losses to each sector's demand. This is a major concern for system planners and operators, as it accounts for a relatively high proportion of total power, with a transmission and distribution loss of 4-6%. Therefore, this paper analyzes the status of loss management based on the current transmission and distribution loss rate of each country and transmission loss management cases of each national power company, and proposes a loss rate prediction algorithm according to the long-term transmission system plan. The proposed algorithm predicts the demand-based long-term evolution and the loss rate of the grid to which the transmission plan is applied.

• Steel and Composite Structures
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• 제5권6호
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• pp.485-513
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• 2005

This paper presents a state-of-the-art on the behaviour of steel joints under fire loading and some recent developments in this field, currently being carried out by the authors. Firstly, a review of the experimental research work on steel joints is presented, subdivided into isolated member tests, sub-structure tests and tests on complete building structures. Special emphasis is placed on the seventh Cardington test, carried out by the authors within a collaborative research project led by the Czech Technical University in Prague. Secondly, a brief review of various temperature distributions within a joint is presented, followed by a discussion of the behaviour of isolated joints at elevated temperature, focussing on failure modes and analytical procedures for predicting the moment-rotation behaviour of joints at elevated temperature. Finally, a description of the coupled behaviour of joints as part of complete structures is presented, describing previous work and investigations on real fire (including heating and cooling phases) currently being carried out by the authors.