• Membrane Journal
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• v.7 no.4
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• pp.167-174
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• 1997

The concentration of silica is required to meet a certain level because silica affects fuel and materials integrity by forming a zeolite layer on fuel cladding surfaces. When the established Feed and Bleed method is employed, nuclear waste increase and the corresponding amount of boric acid is constantly consumed. This study concentrates on minimizing the amount of nuclear waste and consumption of boric acid. Using five different membranes, operating conditions such as temperatur, feed water flow rate, boric acid recovery and silica removal rate were examined. A silica-selective removal system was designed based on the above optimization procedures. Three-stage system was designed with two characteristically different membranes so that it could correspond with the different situation easily. Compared to the pevious results of the Feed and Bleed method, the current method showed that the amount of nuclear waste was reduced to 7%, and the consumption of boric acid to 15.7%.

• Proceedings of the KOR-KST Conference
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• 1998.09a
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• pp.3-16
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• 1998

The goal of the transportation policy of Seoul is to increase the ridership of the subway system by constructing the public transportation network, the subway system. To accomplish this goal, the city of Seoul has been constructing the Metropolitan Subway System. Currently, seven subway lines which connect major areas in Seoul are operating. However, the ridership of subway system was not increased as much as we expected, even though more subway lines have been implemented. It seems that although the length of the subway line was extended, the current way of the subway operation that trains stop at every station cannot satisfy the passenger's need. Thus, we should try to increase the demand by providing quicker services and diversifying the subway operations; changing the point of view is required. This paper introduces the distinctive features of the express subway system and the model for analysing the effects of that system. This paper also presents the results for the feasibility study of the express subway system on the 5th Subway Line and Kyong-Eue Railway Line. Based on the results of the case studies, We can conclude as : First, the express system reduces a total travel time by about $13\%$; in particular, the Kyong-Eue Line is more effective than the subway Line ${\sharp}5$. Second, the shorter headway of express trains increases the time saving effects on subway system although it requests more waiting time to low-speed train passengers. When the service frequency is increased from 5 to 7.5 times/hour, total saved time ratio is about $10\%$ in the Subway Line ${\sharp}5$ and about $18\%$ in the Kyong-Eue Line.

• Tribology and Lubricants
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• v.22 no.2
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• pp.59-65
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• 2006

In hard disk drives as the head to disk spacing continues to decrease to facilitate recording densities, slider disk interactions have become much more severe due to direct contact of head and disk surfaces in both start/stop and flying cases. The slider disk interaction in CSS (contact-start-stop) mode is an important source of particle generation and tribocharge build-up. The tribocharge build-up in the slider disk interface can cause ESD (electrostatic discharge) damage. In turn, ESD can cause severe melting damage to MR or GMR heads. The spindle speed of typical hard disk drives has increased in recent years from 5400 rpm to 15000 rpm and even higher speeds are anticipated in the near future. And the increasing disk velocity leads to increasing disk acceleration and this might affect the tribocharging phenomena of the slider/disk interface. We investigated the tribocurrent/voltage build-up generated in HDD, operating at increasing disk accelerations. In addition, we examined the effects with relative humidity conditions and rest time. We found that the tribocurrent/voltage was generated during pico-slider/disk interaction and its level was about $3\sim16pA$ and $0.1\sim0.3V$, respectively. Tribocurrent/voltage build-up was reduced with increasing disk acceleration. Higher humidity conditions $(75\sim80%)$ produced lower levels tribovoltage/current. Therefore, a higher tribocharge is expected at a lower disk acceleration and lower relative humidity condition. Rest time affected the charge build-up at the slider-disk interface. The degree of tribocharge build-up increased with increasing rest time.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.7-16
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• 2009

This paper proposes a plan which can raise the accuracy of economic benefit estimation in road construction projects. The point of existing economic appraisals may be that the speeds forecasted by models are different from the field speeds because only volumes are calibrated in the road network. The result of such a calibration has an influence on estimating wrong economic benefits in terms of vehicle operating cost savings, travel time savings, and air pollution savings. Then this study performs a calibration when volumes are at the same amount but the calibration between the field speeds and model speeds is different from each other with two different volume-delay functions; the differences of benefits are confirmed according to two different speed calibrations. Three improvement schemes, including the development of a new volume-delay function, are proposed in this study in order to solve the problem of current benefit calculations. The outcome of this study will help practitioners perform more accurate benefit calculations and reasonable economic appraisals.

• Membrane Journal
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• v.23 no.1
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• pp.24-44
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• 2013

The MBR technology has evolved rapidly over the past two decades with significant gains in performance and reliability, and reductions in costs. Membrane bioreactors (MBR) technology is widely recognised as offering a key option for enhanced wastewater treatment or reuse. The objective of this paper is then to critically review the remarkable achievement on the research and commercial applications of membrane bioreactor (MBR) technology and to present current and potential MBR markets on a global scope. This brief review of the technology incorporates five key aspects : 1) evolution of MBR practice, 2) the commercial technologies of MBRs, 3) the largest MBR installations globally (e.g. > $10,000m^3/day$), 4) MBR market growth, and 5) directions for future research. Finally, the development directions of economical, environmental and technical aspects in MBRs; 1) investment costs; 2) effluent water quality; 3) membrane materials and modules; 4) MBR equipment and treatment process; 5) operating costs (higher energy & chemical consumption); and 6) sustainability such as anaerobic MBRs in the coming years were addressed.

• Fire Science and Engineering
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• v.25 no.2
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• pp.71-79
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• 2011

Since 2008 Korea's fire administration has recognized the importance of human resources by introducing a mentoring system for new employees. This mentoring program is helping new employees adapt to the organization quickly and effectively. In addition, prevention inspectors are improving their job ability and expertise by ensuring the mentoring system has been introduced and operated. However, the current operating and fire officials mentoring system has a variety of problems including lack of expertise on the part of the mentors, deficiency of the legal system, lack of mentoring for information and materials, and lack of compensation, and formal mentoring training for mentors. In this study, the fire officials' mentoring system analysis and previous studies on the fire officials' mentoring functions will be analyzed to determine its effect on job performance. Results of this study of fire officials' job ability show that the variables that affect the mentoring program include the role model, business achievement, teaching method, attitude, interest, and achievement.

• Journal of the Korean Society for Library and Information Science
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• v.42 no.4
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• pp.269-290
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• 2008

The aim of this research was to find ways to improve the overall school library management quality and also to help finding solutions to the school library related problems, which could have not been dealt by the individual schools. To achieve the research goal, we analyzed the domestic and foreign cases of the government led supports for the school libraries as well as collaborations between the school libraries and other organizations. We surveyed the principals about the school library operating policies, current status, and requirements as the principals have influence over how the school libraries are managed. One of the findings of the research was that the survey respondents devote their efforts in the collection development but they also required training of the school library staffs. In comparison to the metropolitan and rural areas, the school libraries in the middle to small cities experienced variety of problems in all aspects of their operations. In addition, the middle to small city school libraries had high expectation on the government supports.

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.42-55
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• 1984

The direction of scientific researches on tree improvement and forest management in several universities and research institutes in Japan can be summarized as follows: They put a great emphasis on sugi, Cryptomeria japonica and cypress, Chamaecyparus oblusa which are two major conifer species largerly planted in the Japanese forestry. In the research of sugi, a great concern has been made in evaluating inheritance of forest tree, quantitative characters and genetic parameter of growth, and in breeding for resistance to diseases and insects and to all the natural calamities. Interaction between environmental conditions and genetic nature of tree can be concerned factors in relation with forest damage, together with silvicultural conditions and pest infestation. Selfing hybrids of $F_1$ made from crossing twisted-leaf sugi, defomity leaf type and midori sugi, normal leaf type segregated the normal needle, twisted needle, green leaf and albino leaf type. It seemed that separation of many defomity individuals can be governed by two dominant complementary genes and from the near loci of which it was detected lethal genes. 52% of Japanese forestry is occupied by the small forest landowners like Korean forestry. This made difficulty for forest improvement such as progressive afforestation and for capital accumulation form forestry. The Forest Corporation was established at first in 1959 to aming at productive forestry structure and forest management, and afforestation. For these purpose, 35 Forest Corporations are at moment operating throughout Japan. However, investment in forestry business becomes less attractive since the wage in forest production duction increased in higher trend. than timber price. Therefore, an artifical afforestation becomes yearly decreased. At present. the self-sufficient rate of timber production in Japan is about 35%, and so a great effort is being made to increase self-sufficient rate of timber production.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.627-631
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• 2005

The $(La_{0.8}Sr_{0.2})_{0.95}MnO_3$/yttria-stabilized zirconia (LSM/YSZ) composites were investigated as anode materials for high temperature steam electrolysis using X-ray diffractometry, scanning electron microscopy, galvanodynamic and galvanostatic polarization method. For this purpose, the LSMperovskites were fabricated in powders by co-precipitation method and then were mixed with 8 mol% YSZ powders in different molar ratios. The LSM/YSZ composites were deposited on 8 mol% YSZ electrolyte disks by means of a screen printing method, followed by sintering at temperatures above $1,100^{\circ}C$. From the experimental results, it is concluded that the electrochemical properties of LSM and the LSM/YSZ composites are closely related to their microstructure and operating temperatures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1544-1551
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• 2007

A start-up circuit of the bandgap reference voltage generator of cascode current mirror type with wide operating voltage range and enhanced power-up characteristics is proposed in the paper. It is confirmed by simulation that the newly proposed start-up circuit does not affect the operation of the bandgap reference voltage generatory even though the supply voltage(VDDA) is higher and has more stable power-up characteristic than the conventional start-up circuit. Test chips are designed and fabricated with $0.18{\mu}m$ tripple well CMOS process and their test has been completed. The mean value of measured the reference voltage(Vref) is 738mV and The three sigma value($3{\sigma}$) is 29.88mV.