• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.63-71
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• 2011

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. In this study, we investigated the influence of alkali activator and superplasticizer on the flowability and compressive strength of the alkali-activated mortar in oder to develop cementless alkali-activated concrete using blast furnace slag. In view of the results, we found out that the type and mixture ratio of alkali activator, the type and adding order of superplasticizer results to be significant factors. When cementless alkali-activated mortar using blast furnace slag manufactured with 1:1 the mass ratio of 9M NaOH and sodium silicate, and added superplasticizer before alkali activator in the mixer, we can be secured workability with 180 mm of flow during 1 hours and compressive strength of about 50 MPa under $20^{\circ}C$ curing condition at age of 28days.

• Perspectives in Nursing Science
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• v.13 no.2
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• pp.88-95
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• 2016

Purpose: Gestational weight gain and prepregnancy body weight are important factors of childbirth outcomes, which further cause obesity, metabolic diseases, or psychological problems later in women's lives. Changes in diet, westernized lifestyle, traditional postpartum care, and childbirth at older age are thought to be threats to proper weight management in Korean women of reproductive age. Public health and antenatal care need to focus on the proper body weight management of women by carefully planning pregnancy to postpartum periods. Purpose: This study explored the body weight changes from pregnancy to postpartum and the related characteristics in women within 12 months after childbirth. Methods: A cross-sectional, retrospective study was conducted with 102 Korean women within 12 months after childbirth. Data were collected using an online survey system, and a structured questionnaire available for electronic self-administration was modified to include demographics, obstetrical history, and body weight at 6 time points. The International Physical Activity Questionnaire and Eating Habit Measurement instruments were also used in data collection. A professional survey agency recruited the participants, and data were automatically saved and then analyzed. Results: The average age of the participants was 33.8 years, 48% were housewives and were well-educated. Seventy-two percent of the participants were primiparas and 82% had breastfed their babies. The body mass index (BMI) ranged from 17.3 to 27.8, indicating that 21.5% of the participants were overweight or obese. The mean gestational weight gain was 11.8 kg, and weight loss was apparent during the first 3 months postpartum. The mean decline in weight was 3.4 kg at one year after childbirth. Women wanted to lose 5.6 kg (range: 3~20 kg), however 44% of them reported that they had not engaged in any weight control efforts. Further, 72% of them reported having engaged in a low level of physical activity. Body weight was not associated with women's characteristics, physical activity score, and diet. Conclusion: Women's awareness of gestational weight gain, lifestyle modification, and the risk of prolonged weight retention should be promoted through the antenatal and women's healthcare systems. As pregnancy and childbirth are critical events that affect women's health, integrative education to ensure healthy transition to life after delivery is required.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.2
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• pp.23-33
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• 2011

In this study, a CFPBS (Cone-type Friction Pendulum Bearing System) was developed which controls the acceleration delivered to the structure to prevent damage and degradation of the critical communication equipment in case of an earthquake. The isolation performance of the CFPBS was evaluated by numerical analysis. The CFPBS was manufactured in the shape of a cone differenced from the existing FPS (Friction Pendulum System), and a pattern was engraved on the friction surface. The natural frequencies of the CFPBS were evaluated from a free-vibration test with the seismic isolator system consisting of four CFPBSs. In order to verify its earthquake-resistant performance, a numerical analysis program was created from the equation of the CFPBS induced from the equations of motion. A simplified theoretical equation of the CFPBS was proposed to manufacture the equipment which could demonstrate the necessary performance. Artificial seismic waves satisfying the maximum earthquake scale of the Korean Building Code-Structural (KBC-2005) were created and verified to review the earthquake-resistant performance of the CFPBS by numerical analysis. The superstructural mass of the CFPBS and skew angle of the friction surface were considered for numerical analysis with El Centro NS (1940), Kobe NS (1995) and artificial seismic waves. The CFPBS isolation performance evaluation was based on the results of numerical analysis and the executed comparative analysis between the results from numerical analysis and the simplified theoretical equation under the same conditions.

• KSBB Journal
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• v.16 no.2
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• pp.188-199
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• 2001

A gene encoding the dextransucrase(dsCB) that synthesizes mostly $\alpha-(1\rightarrow6)$ linked dextran with low amount(10%) of $\alpha-(1\rightarrow3)$ branching was cloned and sequenced from Leuconostoc mesenteroides B-742CB. The 6.1 kbp DNA fragment carrying dsCB showed one open reading frame(ORF) composed of 4,536bp. The deduced amino acid sequence shows that it begins from the start codon(ATG) at position 698 of the cloned DNA fragment and extends to the termination condon(TAA) at position 5,223. The enzyme is consisted of 1,508 amino acids and has an calculated molecular mass of 168.6kDa. This calculated Mw was in good agreement with an activity band of 170kDa on non-denaturing SDS-PAGE. A recombinant E. coli DH5 $alpha$ harboring pDSCB produced extracellular dextransucrase in 2% sucrose medium, and synthesized both soluble and insoluble dextran. To compare the properties of enzyme with B-742CB dextransucrase, the acceptor reaction, hydrolysis of dextran and methylation were performed. The expressed enzyme showed the same properties as B-742CB dextransucrease, but its ability to synthesize $\alpha-(1\rightarrow3)$ branching was lower than that of B-742CB dextransucrase. In order to identify the critical amino acid residues known as conserved regions related to catalytic activity, Asp-492 was replaced with Asn. D492N resulted in a 1.6 fold decrease in specific activity.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.6 s.165
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• pp.879-891
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• 2007

Forecasting is a critical task for fashion companies because of continuous change in fashion and long process lead-time. Therefore, it is of great importance for both scholars and companies to understand how forecasted fashion styles are accepted by consumers. This research aimed to investigate consumer acceptance of fashion styles in Korea. The study examined and compared oversea collections of women's wear to the street fashion in Korea for seven seasons from 02 s/s to 05 s/s. Information on oversea collections were obtained from the magazine, Fashion Show, and the street fashion information from Seoul Fashion Design Center. The results showed that overall trends presented in oversea collections have been well accepted, while acceptance of specific styles or items varied. During the period of this research, sporty style and feminine style were very strong in the street fashion. Many styles and items were modified and selectively accepted probably because of cultural differences and limitations of mass production. Some styles which were presented in oversea collections were not accepted in Korea, and at the same time some cases were observed only in the street fashion in Korea. The results of this study provide guidelines for Korean apparel companies in merchandise planning and empirical findings to deepen the understanding on Korean society with respect to fashion.

• Archives of design research
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• v.12 no.2
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• pp.133-144
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• 1999

Considering product as mass of information, it is very critical for designers to have good means of accessing to and organizing information on products. However, designers conventionally depend on their experience, bunch of catalogues, or short visit to some fairs for gathering information on products. There are no systematically organized information for designing new products. If any, those are ones developed by market researchers or engineers who speak fundamentally different language from designers. It is needed to develop the information system through which designer can get insights on the essence of product and communicate information with various persons involved in new product planning. At first, the design information in product planning is discussed and the necessity of development of new design information system is emphasized. Then, product is understood as a composite of various attributes and a set of fundamental attributes of product is defined by surveying and summarizing existing theories of product attributes: namely technological, human, and market attributes. The possibility of new design information system is explored by analyzing various relationships between attributes of different products. Computer program 'DISPP' displays various visual information of product itself, perceptual map, trend slope, profile chart and general information of manufacturer, style, color, price, size. Finally, findings of thesis are concluded and further prospects of the study are proposed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.233-246
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• 2009

The partitioning of evapotranspiration (ET) into evaporation (E) and transpiration (T) is critical in understanding the water cycle and the couplings between the cycles of energy, water, and carbon. In forests, the total ET measured above the canopy consists of T from both overstory and understory vegetation, and E from soil and the intercepted precipitation. To quantify their relative contributions, we have measured ET from the floors of deciduous and coniferous forests in Gwangneung using eddy covariance technique from 1 June 2008 to 31 May 2009. Due to smaller eddies that contribute to turbulent transfer near the ground, we performed a spectrum analysis and found that the errors associated with sensor separation were <10%. The annual sum of the understory ET was 59 mm (16% of total ET) in the deciduous forest and 43 mm (~7%) in the coniferous forest. Overall, the understory ET was not negligible except during the summer season when the plant area index was near its maximum. In both forest canopies, the decoupling factor ($\Omega$) was about ~0.15, indicating that the understory ET was controlled mainly by vapor pressure deficit and soil moisture content. The differences in the understory ET between the two forest canopies were due to different environmental conditions within the canopies, particularly the contrasting air humidity and soil water content. The non-negligible understory ET in the Gwangneung forests suggests that the dual source or multi-level models are required for the interpretation and modeling of surface exchange of mass and energy in these forests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.26-35
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• 2016

As a potential clean energy resource, the production and consumption of hydrogen gas are expected to gradually increase, so that hydrogen related studies are also increasing. The thermal and chemical properties of hydrogen result in its high flammability; in particular, there is a high risk if leaks occur within an enclosed space. In this study, we applied the computational fluid dynamics method to conduct a numerical study on the leakage behavior of hydrogen gas and compared these numerical study results with an experimental study. The leakage hole diameter was selected as an important parameter and the hydrogen gas dispersion behavior in an enclosed space was investigated through various analytical methods. Moreover, the flammable regions were investigated as a function of the leakage time and leakage hole size. We found that the growth rate of the flammable region increases rapidly with increasing leakage hole size. We also investigated the relation between the mass flow rate and the critical time when the hydrogen gas reaches the ceiling. The analysis of the monitoring points showed that the hydrogen gas dispersion behavior is isotropic and independent of the geometry. We found that the concentration of gas in an enclosed space is affected by both the leakage flow rate and amount of gas accumulated in the enclosure.

• Resources Recycling
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• v.18 no.2
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• pp.39-50
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• 2009

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of fly ash, a by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the source of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effective in the reduction of $CO_2$ gas. In this study, we investigated the influence of the compressive strength of mortar on alkaline activator and curing condition in order to develop cementless fly ash based alkali-activated concrete. In view of the results, we found out that it was possible for us to make alkali-activated mortar with 70MPa at the age of 28days by using alkaline activator manufactured as 1:1 the mass ratio of 9M NaOH and sodium silicate and applying the atmospheric curing after high temperature at $60^{\circ}C$ for 48hours.

• Land and Housing Review
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• v.2 no.4
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• pp.529-538
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• 2011

Recently, one of the critical issues in Korea is the huge debt and future role of Korea Land and Housing Corporation. In this regards, the purpose of this study is to get implications from other public housing agencies in Asian countries such as UR of Japan, HDB of Singapore and HA of Hongkong. The changes of housing policy since 1960s, business and financial structure of housing agencies in each nation are investigated and compared. As a result, some policy directions can be proposed as follows : review of current mass housing program, relaxing qualifications for public rental housing, promotion of urban renewal projects, reinforcing cooperation with private sector and local governments, more government's support to LH's financing and loss from businesses for public interests and re-evaluation of LH's debt. The contribution of this study is that suggestions to improve housing policy and to alleviate financial problem of LH are based on the actual conditions of public housing agencies in Asian countries where the housing policy implementation system is similar to Korea, not on the theoretical basis.