• Journal of the Korea Concrete Institute
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• 제24권6호
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• pp.677-684
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• 2012

In recent years, extension of life span of buildings is becoming an important issue in our society. To improve the life span of buildings, rhamen structure construction and long-spanned structures are advantageous. And in order to achieve this goal, structural elements of buildings must be light and slender. As an alternative method, general porous slabs are used frequently domestically and internationally. But the study on the porous slabs using T-deck plate and assembly of light weight precast construction is insufficient at present. In this study, flexural and fatigue tests were performed on six specimens to verify structural performance and serviceability. The main parameters of the specimens were light weight and T-deck plate construction possibility as well as slab thickness. The test results indicated that the strength of porous slabs using T-deck plate and assembly of light weight were much better than general RC slabs and porous slabs without T-deck plate. And stiffness was much better than that of other tested slabs.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.143.1-143.1
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• 2010

고분자 전해질막 연료전지(Polymer Electrolyte Membrane Fuel Cell; PEMFC)는 수소를 이용하여 전기를 발생시키는 친환경적이고 이상적인 발전장치로 고효율과 높은 전류밀도를 가지며 그 응용분야가 다양하다. 저온에서 작동하는 PEM fuel cell은 전극에서 효과적인 산화환원반응을 위해 그 촉매로 활성이 우수한 Pt(Platinum)을 사용하고 있으나, Pt의 높은 가격은 연료전지의 상용화에 걸림돌이 되고 있다. 본 연구에서는 연료전지의 Pt/C 촉매 층에서 Pt의 분산성을 높여 Pt의 담지량을 줄이고 작동 중 발생하는 Pt의 응집 현상을 방지하여 Pt의 수명을 연장시킬 목적으로, Au(gold) 나노입자를 첨가한 Pt-Au/C 복합나노촉매를 제조하였다. 본 발표에서는 합성된 Pt-Au/C 복합촉매 중 Au 첨가량이 Pt 촉매의 활성에 미치는 영향을 조사하기 위하여, 복합촉매 중에 금속(Pt+Au)의 총 함량이 30 wt.%와 40 wt.% 인 Pt-Au/C 촉매에 대하여 각각 Au 첨가량을 변화시켜, cyclic voltammetry 법에 의해 Au 첨가 효과를 조사한 결과에 대하여 보고하고자 한다. Au 나노입자를 제조하기 위한 출발 물질로는 $HAuCl_4{\cdot}4H_2O$를 이용하였고 trisodium citrate와 $NaBH_4$를 환원제로 하여, 입경이 5~8 nm 인 Au 콜로이드를 제조하였다. Pt-Au/C 복합나노촉매를 제조하기 위하여 먼저 Au/C 복합분체가 제조되었다. 0.03g의 carbon이 첨가된 carbon 현탁액에 합성된 Au 콜로이드 수용액을 첨가한 후 24시간 동안 교반하여 Au/C 복합분체를 제조하였다. 이 Au/C 복합분체에 $H_2PtCl_6{\cdot}6H_2O$ 수용액을 현탁하고 methanol 을 환원제로 사용해 Pt를 환원 석출시켜 Pt-Au/C 복합촉매를 제조하였다. Pt-Au/C 복합 나노촉매에서 Pt와 Au를 다양한 비율(3:1, 2.5:1.5, 2:2)로 합성하였으며 Pt-Au/C 복합촉매 중 금속(Pt+Au) 촉매의 총 함량은 30 wt.%와 40 wt.%로 각각 제조되었다. Au 나노입자 콜로이드의 분산성은 UV-visible spectrum의 흡광도에 의해 관찰되었고, Pt-Au/C 복합 나노촉매의 형상 및 분산성 분석은 transmission electron microscopy(TEM)에 의해 이루어졌다. 또한, 촉매의 전기화학적 특성평가는 cyclic voltammetry(CV)에 의해 조사되었다.

• Journal of the Korean Society of Radiology
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• 제11권5호
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• pp.387-392
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• 2017

When an infant has visited a hospital due to skull fracture, the rupture of a blood vessel, or skin wounds on the head resulted from an incident, accident, traffic accident, or disease, he/she becomes to undergo anterior/posterior and lateral skull imaging, which is a head test at the department of radiology. In the head test, if the adult skull imaging grid is applied to the imaging, the secondary radiation will be removed to enhance the contrast of the image. However, among the radiation exposure conditions, the tube voltage should be enhanced by 8~10 kVp leading to an increase in the patient exposure. The present study was conducted under assumption that if the same images can be obtained from infant skull imaging without using the skull imaging grid, the exposure dose will be reduced and the artifacts due to grid cut off can be prevented. The researcher measured the radiation dosage using a radiation meter and conducted the subjective evaluation (ROC, receiver operating characteristic) among medical image evaluation methods. Based on the results, when the images were taken without using the grid, the exposure dose was reduced by 0.019 mGy in the anterior/posterior imaging and by 0.02 mGy in the lateral imaging and the image evaluation score was higher by 4 points. In conclusion, if the images of the skulls of infants that visited the hospital are taken with out using the grid, the exposure dose can be reduced, the image artifacts due to grid cut off can be prevented, and the lifespan of the X-ray tube will be extended.

• Journal of the Korean Society for Library and Information Science
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• 제51권3호
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• pp.45-64
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• 2017

The purpose of this study is to understand the direction of the community reading campaign in the U.S.A. known as 'One Book, One City' reflected in the books selected for this campaign for the past 20 years in terms of their classification numbers, subject headings, publication dates, and genres. Analyzed are the author and state lists of 'One Book, One City' Reading Promotions Projects available from the website of the LC (Library of Congress) Center for the Books, and bibliographic records of 735 books selected in only one 'One Book' program, accessed from LC OPAC. Major findings include continuing influences of the all-time favorite 'One Book' selections, including To Kill a Mockingbird and the extension of their span of life through The Big Read, preference for the recent publications, importance of P (Literatures and Languages) Class (530 titles, 72.1%) and PS(American Literatures) subclass (307 titles, 57.9%) in the LC Classification Scheme, distribution of books in 43 genres, including domestic fiction, historical fiction, and psychological fiction, etc., the use of 535 unique LC subject headings and much interests in "City and town life" (10 titles) and "World War, 1939-1945" (8 titles), and prominence of subject groups which begin with "African American..." and "Woman..." out of 96 groups of subject headings. It is found that the subjects and focus of the selected books expand from integration, understanding, integrity to human rights, environment, peace, etc. The limitations of this study is that the influence of the selected books and the changes in communities are not properly analyed.

• Journal of the Society of Disaster Information
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• 제16권2호
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• pp.276-290
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• 2020

Purpose: The construction history of domestic port facilities has been more than 100 years, and until recently, modern facilities have been continuously built and expanded. However, it is not easy to keep the required performance conditions at the time of initial construction due to changes in the marine environment and increase in volume. In particular, in the case of harbor structures that have a long service life, safety performance and function management are becoming very important due to the increase in the size of ships, the increasing frequency of use, and the increase in the scale of natural disasters. Method: Therefore, this study investigates the state change by structural type of port facilities and analyzes the rehabilitation activities and the history that contribute to the performance improvement and life extension activities. Result: Through this, we distinguished between performance improvement cost (CAPEX) and repair maintenance activity (OPEX) that can be used to establish port facility maintenance strategy, and suggested cost model that can be used to establish maintenance strategy. Conclusion: These studies are expected to contribute greatly to mid- to long-term investment decisions.

• Korean Journal of Food Science and Technology
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• 제47권6호
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• pp.733-737
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• 2015

For testing the ultraviolet (UV)-blocking property of functional films coated with Nano-$TiO_2$ particles, UV-Vis spectra of oriented polypropylene (OPP) films uncoated and coated with $TiO_2$ of 3% and 5% in Polyurethane (PU) and polyvinyl butyral (PVB)-Cellulose binders were measured. The result of UV-Vis analyses showed that the film coated with 5% $TiO_2$ in PVB binders had a significant effect on UV protection of 90% compared with the film uncoated. Also The result of The photodegradation of methylene blue (MB), OPP films coated with 5% in both PU and PVB binders had a high photocatalytic activity for MB degradation. To evaluate the effect of the developed functional film coated with Nano-$TiO_2$ particles, fresh soybean sprouts were used. Nano-$TiO_2$ coated film was observed to decompose the off-flavor produced by soybean sprouts within packages during distribution, but uncoated film did not. Therefore, Nano-$TiO_2$ coated film package could give the greatest effect in extending the shelf life of soybean sprouts.

• Journal of Life Science
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• 제22권6호
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• pp.828-836
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• 2012

The objective of the current study was to determine the effects of the extracts isolated from the fruit body of Flammulina velutipes cultivated with oriental herbal plants on mouse splenocytes, B cells, and macrophages in vitro. The ethanol extracts B (EEB) directly induced the proliferation of spleen cells in a dose-dependent manner and increased IL-6, TNF-${\alpha}$, and IFN-${\gamma}$ synthesis. The EEB also increased the proliferation of B cells in a dose-dependent manner. The production of immunoglobulin M, G1, G2a, G2b, and IgG3 in the presence of the EEB increased progressively in the culture supernatant. When the EEB were used in macrophage cell line (RAW264.7) stimulation, there was a marked induction of NO synthesis in a dose-dependent manner and an increased IL-6, TNF-${\alpha}$, and GM-CSF synthesis. Intraperitoneal injection with EBB showed life prolongation effect of 16.1% in mice previously inoculated with sarcoma-180, respectively. These results suggest that the capacity of the EEB isolated from the fruit body of Flammulina velutipes cultivated with oriental herbal plants seems to act as a potent immunomodulator causing augmentation of immune cell activity, and with the absence of notable side-effects, Flammulina velutipes EEB could be used as a biological response modifier having possible therapeutic effects against immunological disorders. This study also showed that functional components of Flammulina velutipes were possibly improved by incorporating oriental herbal plants in a growth medium.

• Journal of fish pathology
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• 제10권1호
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• pp.45-52
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• 1997

A protein-bound polysaccharide preparation, PS-K, isolated from Coriolus versicolor was evaluated for its ability to enhance resistance against Edwardsiella tarda, causal agent of classical edwardsiellosis in tilapia, Oreochromis niloticus. Fish treated with a dose rate of 0.1 mg PS-K $g^{-1}$ body weight were challenged by intraperitoneal injection of E. tarda with different concentrations. Against low burdens of injections($1.2{\times}10^7$ and $1.2{\times}10^8$ cfu/fish), PS-K treated fish did not show any mortality compared to 50% and 100% mortality of control groups, respectively. However there was no increase of resistance against challenge with high concentrations of E. tarda ($1.2{\times}10^9$ and $1.2{\times}10^{10}$cfu /fish) except few days delaying of death. Tilapia injected with PS-K one day after intraperitoneal inoculation of E tarda($1.2{\times}10^7$ cfu/fish) showed 100% survival rate compared to control group of 50% survival rate. The result indicates the potential of PS-K as a prophylactic agent in aquaculture. The increased antibody response in fish received PS-K one week prior to FKC administration suggested the influence of PS-K on the specific humoral immunity and increased resistance against bacterial infection.

• Korean Journal of Food Science and Technology
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• 제33권4호
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• pp.469-473
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• 2001

Fuji apples were sliced and dipped in distilled water, 1% (w/v) ascorbic acid and 1% (w/v) oxalic acid. After minimal processing, the slices were packaged with three films which have different gas transmission rate and stored in cold room$(0-2^{\circ}C)$. The visual quality, gas composition, pH, texture, soluble solids content and titratable acidity were determined. The most deteriorative effects on quality were produced by browning of flesh. Ascorbic acid inhibited the development of browning and extended storage life from 7 days of control to 14 days at $0-2^{\circ}C$. Minimally processed Fuji apple treated with ascorbic acid and P640 film showed exhausting of oxygen in the packaging after 14 days. It showed only a slight reduction of pH from 3.73 to 3.72. The visual quality, gas composition, pH, texture, soluble solids content, titratable acidity were slightly changed, indicating that higher quality was maintained during storage. Ascorbic acid inhibited the development of browning and extended storage life of fresh-cut Fuji apple.

• International Journal of Highway Engineering
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• 제13권2호
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• pp.139-145
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• 2011

The practice of asphalt pavement recycling has grown rapidly over the decade, one of which is the cold in-place recycling with the foamed asphalt (CIR-foam) or the emulsified asphalt (CIR-emulsion). Particularly, in Iowa, the CIR has been widely used in rehabilitating the rural highways because it significantly increases the service life of the existing pavement. The CIR layer is typically overlaid by the hot mix asphalt (HMA) to protect it from water ingress and traffic load and obtain the required pavement structure and texture. Most public agencies have different curing requirements based on the number of curing days or the maximum moisture contents for the CIR before placing the overlay. The main objective of this study is to develop a moisture loss index that the public agency can use to monitor the moisture content of CIR layers in preparation for a timely placement of the wearing surface. First, the moisture contents were measured in the field using a portable time domain reflectometry (TDR) device. Second, the weather information in terms of rain fall, air temperature, humidity and wind speed was collected from the same location. Finally, a moisture loss index was developed as a function of initial moisture content, air temperature, humidity and wind speed. The developed moisture loss index based on the field measurements would help the public agency to determine an optimum timing of an overlay placement without continually measuring moisture conditions in the field.