• 멤브레인
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• 제30권2호
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• pp.79-96
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• 2020

환경오염과 화석연료의 문제로 인한 2차 에너지 변환 및 저장 장치의 개발이 활발하게 진행되고 있다. 이러한 에너지 변환장치들은 전기화학적 시스템을 기본으로 운영되고 있으며 이온교환막은 각 공정의 성능을 결정짓는 중요한 요소이다. 따라서 에너지 시스템의 효율 증대 및 성능 향상을 위해서는 적합한 물성을 갖는 이온교환막 개발이 필요하다. 이러한 이온교환막은 크게 양이온교환막, 음이온교환막, 바이폴라막으로 분류되고 있으며, 이들 막들은 화학적, 물리적, 형태학적 특성에 따라 다양한 용도을 갖고 있다. 본 총설에서는 이온교환막의 주요한 특징과 함께 이들의 제조 방법에 대해 기술했다. 이어서 이온교환막을 이용하여 최근 개발되고 있는 전기화학 시스템에 기반을 둔 역전기 투석, 레독스 흐름 전지, 수전해 공정에 대해서 소개하고, 각 에너지 공정에서 이온교환막이 갖는 역할과 조건에 대해서 설명하였다.

• Journal of the Korean Data and Information Science Society
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• 제20권4호
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• pp.655-660
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• 2009

최근의 글로벌경제위기 상황에서 국내 금융외환시장이 높은 환율변동을 보이며 불안한 모습을 보이고 있다. 따라서 그 어느 때보다 금리, 환율 등 가격변수들의 움직임 및 이들 간의 관계에 대한 관심이 높다. 본 연구에서는 국내시장을 중심으로 환율, 금리의 추이 및 인과관계에 대하여 연구하였다. 글로벌경제위기 상황에서 원/달러환율, 콜금리의 움직임에서 나타나는 주요 특징을 알아보고, 교차상관분석 및 그랜저 인과관계검정 등을 이용하여 두 변수간의 상호연관관계에 대하여 선도/지연 관계를 중심으로 분석하였다.

• 한국도서관정보학회지
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• 제38권1호
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• pp.135-156
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• 2007

본 연구에서는 상업적인 지식정보유통업체(지식거래소)들의 지식정보유통구조를 분석하고자 하였으며, 다음과 같이 크게 네 가지로 나누어 지식거래소의 지식정보유통현황을 분석하고자 하였다. 첫째, 지식거래소에서 거래되는 지식정보의 유형, 지식정보량, 그리고 사이트 이용자의 규모 등을 분석하였다. 둘째, 지식거래소들의 지식정보유통구조를 분석하였다. 넷째, 저작권 침해가 발생할 수 있는 소지를 구체적으로 발견해 내고 설문조사를 통해 저작권 해결 현황을 파악하고자 하였다. 넷째, DRM의 적용 여부는 물론 DRM 적용시 부여되는 사용권한 제어방법에 대해서도 알아보고자 하였다.

• 환경위생공학
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• 제14권1호
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• pp.42-53
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• 1999

A study on the synthesis of zeolite from coal fly ash from power plant was carried out to reduce environmental problems and reuse industrial waste. The synthesized zeolite was proved to be Zeolite 4A type by means of the XRD and SEM analysis, and then the synthesized zeolite was used as an absorbent to remove the $NH_4^+$ ions in the wastewater and water. In the ion exchange of single $NH_4^+$ ions by the natural zeolite and the synthesized zeolite, the ion exchange reached equilibrium within 10 min. and 1hr, respectively. The amount of ion exchanged $NH_4^+$ to the unit weight of natural zeolite and zeolite 4A were 1.09 and 3.54 meq/g respectively, and the amount of $NH_4$ ion exchanged by the synthesized zeolite was higher than by the natural zeolite. The ion exchange kinetics fitted very well to the Feundlich and Langmuir isotherm. The effects of coexisting cations on the ion-exchange properties of zeolites were studied in order to apply them to water treatment. In the bisolute-system of the $NH_4^+-K^+$ and $NH_4^+-Na^+$ systems, the ion exchange capacity was smaller than the single $NH_4^+$ ion system. The effects of coexisting cations on the ion exchange system by the natural zeolite and the synthesized zeolite were found to be $K^+>Na^+$ and $Na^+>K^+>>Mg^{2+}>Ca^{2+}$, respectively.

• 통상정보연구
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• 제12권1호
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• pp.99-121
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• 2010

This paper reviews the categories and properties of risk measures, analyzes the classes and structural equations of volatility forecasting models, and presents the practical methodologies and their expansion methods of estimating and forecasting the volatilities of exchange rates using Excel spreadsheet modeling. We apply the GARCH(1,1) model to the Korean won(KRW) denominated daily and monthly exchange rates of USD, JPY, EUR, GBP, CAD and CNY during the periods from January 4, 1998 to December 31, 2009, make the estimates of long-run variances in the returns of exchange rate calculated as the step-by-step change rate, and test the adequacy of estimated GARCH(1,1) model using the Box-Pierce-Ljung statistics Q and chi-square test-statistics. We demonstrate the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the monthly series except the semi-variance GARCH(1,1) applied to KRW/JPY100 rate. But we reject the adequacy of GARCH(1,1) model in estimating and forecasting the volatility of exchange rates in the daily series because of the very high Box-Pierce-Ljung statistics in the respective time lags resulting to the self-autocorrelation. In conclusion, the GARCH(1,1) model provides for the easy and helpful tools to forecast the exchange rate volatilities and may become the powerful methodology to overcome the application difficulties with the spreadsheet modeling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.586-587
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• 2011

에디슨이 전기를 발명한 후 지난 100년간 전력산업은 증가하는 전력수요에 대응하기 위해 공급측면에서 발전소 및 송배전 설비 건설을 통해 전력공급 문제를 해결하여 왔다. 이 과정에서 화석연료 사용으로 인한 지구환경오염, 화석연료 고갈에 따른 에너지 가격 급등등으로 신규 대체자원의 개발과 수요측면에서 대응방안 마련이 절실한 상황에 이르렀다. 이러한 문제를 해결하고자 하는 전력산업의 패러다임이 스마트그리드이며, 본 논문에서는 스마트그리드 핵심자원인 수요측자원에 대해 스마트그리드 제주실증단지 전력시장에서의 수요자원 운영방안에 대한 체계를 제시하고자 한다.

• 한국미생물·생명공학회지
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• 제40권2호
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• pp.157-162
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• 2012

In this study, we have for the first time applied increased surface area fractional precipitation in order to decrease the particle size of the anticancer agent paclitaxel from plant cell cultures. When compared with the case where no surface area increasing material was employed, the addition of ion exchange resin as a surface area increasing material resulted in a considerable decrease in the size of the paclitaxel precipitate. When ion exchange resin was used, the paclitaxel particles were four to five times smaller, having less than a 20 ${\mu}m$ radius, than those obtained in the absence of ion exchange resin. This is presumably because the growth of paclitaxel particles was impeded by the addition of ion exchange resin. The size of the paclitaxel precipitate also depended on the material used to increase the surface area, a result considered to be due to differences in the affinity between the particular ion exchange resin used and the paclitaxel particles. The yield of paclitaxel was significantly improved when ion exchange resin was used as a material to increase surface area. Paclitaxel, with a reduced particle size due to the addition of a surface area increasing material during the fractional precipitation process, is believed to be particularly useful for practical applications of the drug.

• 성인간호학회지
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• 제15권3호
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• pp.463-471
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• 2003

Purpose: This study was aimed at providing scientific evidence for minimizing ventilator-associated pneumonia(VAP) by identifying appropriate timing of exchange of circuit for mechanical ventilator that is well suitable for the medical environment of intensive care units of hospitals in Korea. Method: This was a quasi-experimental study with a convenience sample of 19 adult subjects aged over 18 years who were admitted to the NS ICU of C university hospital, and placed on mechanical ventilator. The subjects were placed in two groups, compared on the incidence rate of VAP after they received exchange of circuit either at 1-week interval (N =10) or 2-week interval (N = 9). Result: 1) When considering 1000 days as the standard unit of analysis for incidence, the incidence rate of VAP was 7.19 cases at the 1-week cycle exchange group and 15.23 at the 2-week cycle exchange group, showing no statistically significant difference between the two groups. 2) There were a total of 3 types of bacteria isolated from the patients with VAP, including 2 cases with P. aeruginosa, 1 case with Streptococcus group F and A. baumannii. Conclusion: With thorough hand washing and strict management of tracheal tube of mechanical ventilator as well as use of tracheal intubation techniques, exchange cycle of circuit of mechanical ventilator by nurses may be changed from 1-week to 2-week interval.

• 동아시아경상학회지
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• 제3권4호
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• pp.9-15
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• 2015

The exchange rate is a very important macro variable that has influence on the whole economy and has, therefore, been the topic of many discussions amongst policymakers, academics and other economic agents. The issue of whether to have a fixed, pegged or floating exchange rate regime was highly debated during the 1970s. The purpose of this paper is to investigate what factors determine the exchange rate in Somalia. Quantitative research methodology has been employed to develop regression model using time series data for the period of 12 years. The regression model has been developed based on Quantity theory of money, purchasing power parity and uncovered interest rate parity theory. Somalia is on the countries where the highest exchange rate volatility exists; for example in 2012, the rate jumped 29% percent and two weak later dropped 21%, when Turkish humanitarian aid agencies injected the market a lot of U.S dollar. Based on my study using regression model for time series data of 12 years, the four factors are mainly attributable for the exchange rate volatility of Somalia; these factors include the balance of payment, inflation rate, money supply (mostly come from remittance and NGOs) and Bank profits.

• 한국세라믹학회지
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• 제52권1호
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• pp.23-27
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• 2015

Recently, the use of ion-exchange strengthened glass has increased sharply, as it is now used as the cover glass for smart phone devices. Therefore, many researchers are focusing on methods that can be used to strengthen ion-exchange glass. However, research on how the improved strength can be maintained under thermal environment of device manufacturing is still insufficient. We tested the degradation of the characteristics of ion-exchange soda-lime glass samples, including their surface compressive stress characteristics, the depth of the ion-exchange layer (DOL), flexural strength, hardness, and modulus of rupture (MOR) values. Degradation of the characteristics of the ion-exchange glass samples occurred when they were heat-treated at a temperature that exceeded $350^{\circ}C$.