• 대한기계학회논문집B
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• 제30권10호
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• pp.935-941
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• 2006

Many important properties in colloidal systems are usually determined by surface charge $({\zeta}-potential)$ of the contacted solid surface. In this study, ${\zeta}-potential$ of glass ${\mu}-channel$ was evaluated from the electro-osmotic velocity distribution. The electro-osmotic velocity inside a glass f-channel was measured using a micro-PIV velocity field measurement technique. This evaluation method is more simple and easy to approach, compared with the traditional streaming potential technique. The ${\zeta}-potential$ in the glass ${\mu}-channel$ was measured fur two different mole NaCl solutions. The effect of an anion surfactant, sodium dodecyl sulphate (SDS), on the electro-osmotic velocity and f-potential in the glass surface was also studied. In the range of $0{\sim}6mM$, the surfactant SDS was added to NaCl solution in few different mole concentrations. As a result, the addition of SDS increases ${\zeta}-potential$ in the surface of the glass ${\mu}-channel$. The measured $\zeta-potential$ was found to vary from -260 to -70mV. When negatively charged particles were used, the flow direction was opposite compared with that of neutral particles. The ${\zeta}-potential$ has a positive sign for the negative particles.

• International Journal of Precision Engineering and Manufacturing
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• 제7권4호
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• pp.40-46
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• 2006

The market of programmable implantable pumps has bound to a monopolistic situation, inducing high device costs, thus making them inaccessible to most patients. Micro-mechanical and medical innovations allow improved performances by reducing the dimensions. This affects the consumption and weight, and, by reducing the number of parts, the cost is also affected. This paper presents the procedure followed to design an innovative implantable drug delivery system. This drug delivery system consists of a low flow pump which shall be implanted in the human body to relieve pain. In comparison to classical known solutions, this pump presents many advantages of high interest in both medical and mechanical terms. The first section of the article describes the specifications which would characterize a perfect delivery system from every points of view. This concerns shape, medication, flow, autonomy, biocompatibility, security and sterilization ability. Afterwards, an overview of existing systems is proposed in a decisional tree. Positive displacement motorized pumps are classified into three main groups: the continuous movement group, the fractioned translation group and the alternative movement group. These systems are described and the different problems which are specific to these mechanisms are presented. Since none of them fully satisfy the specifications, an innovation is justified.. The decisional tree is therefore extended by adding new principles: fractioned refilling and fractioned injection within the fractioned translation movement group, spider guiding system within the alternative translation movement group, rotational bearing guided device and notch hinge guided device in the alternative rotation movement group.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권6호
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• pp.46-52
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• 2010

Derivative analysis, based on the derivative of the drawdown as a function of time (i.e., rate of drawdown change), was applied to the evaluation of hydraulic parameters of the aquifer as an aid of the aquifer test interpretation based on the Theis solutions. Pumping tests were conducted at a coastal fractured aquifer in Muan county, Korea, of which the drawdown data, measured at the two observation wells, were used for derivative analysis. Wellbore storage and transition period were hard to identify at conventional log-log and semi long plots, but was easily recognized by distinctive curves of positive unit slope, hump and negative unit slope in the derivative plot. For the observation well of OW-2 at which wellbore storage and transition lasted over an hour, conventional aquifer analysis would suffer from the uniqueness problems and in further result in erroneous hydraulic parameters. Derivative analysis was found to be effective for distinguishing the drawdown data directly reflecting the aquifer property from those reflecting non aquifer effects such as wellbore storage and transition, which offers a unified methodology to yield correct hydraulic parameters from aquifer test data.

• Mass Spectrometry Letters
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• 제10권4호
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• pp.103-107
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• 2019

Low-temperature plasma (LTP) ionization is one of the ambient ionization methods typically used in mass spectrometry (MS) for fast screening of chemicals with minimal or no sample preparation. In spite of various advantages of LTP ionization method, including simple instrumentation and in-situ analysis, more general applications of the method are limited due to poor desorption of analytes with low volatilities and low ionization efficiencies in the negative ion mode. In order to overcome these limitations, an ultrasonic vibrator of a commercial hand-held humidifier was interfaced with an LTP ionization source, which generated microdroplets from sample solutions and assisted with LTP ionization. Ionization behaviors of various chemicals in microdroplet-assisted LTP (MA LTP) were tested and compared with typical LTP ionization from dried samples applied on a surface. MA LTP efficiently ionized small organic, amino, and fatty acids with low volatilities and high polarities, which were hardly ionized using the standard LTP method. Facile interaction of LTP with ultrafine droplets generated by ultrasonic resonator allows efficient ionization of relatively non-volatile and polar analytes both in the positive and negative ion modes.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.141-148
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• 2005

This study as a demand of reconstruction allows the longevity of the multi complex, analyze the problems and solutions for a long term maintenance planning scheme, and how to save contingency fund to utilize. The major role of the multi complex housing market reflects Positively on our valuable society, provides a better life of environment on top of longevity and for the superior living duality. For a achievement and improvement existing long term maintenance Plan and contingency fund system should be considered as follows. First, shall be expanded more units of house as smaller group. Second, advice from expert shall be reconsidered, eliminated, and protected reorganizing an informal reconstruction planning comparatively legal procedure must be renegotiated and pursued. Third, the fund which saved for the contingency has to clarified as tax free item by government. It's not only mistreated as a limitation of personal asset but also treated as national source Despite of rather compulsive and constructive method must be noticed by whoever owns for, more positive follows, promotion and directing must be able to guide its understanding and adherence of importance and inevitability.

• 한국게임학회 논문지
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• 제11권2호
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• pp.93-104
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• 2011

차세대 게임으로 주목받는 체감형 게임의 발전을 위해서, 본 연구는 현재 체감형 게임의 현황을 파악하고, 하드웨어보다 미흡한 콘텐츠 개발의 문제점을 분석한다. 우선, 체감형 게임 콘텐츠가 지닌 문제점을 세 가지로 구분했다. 그리고 콘텐츠의 수요와 편향된 장르의 문제, 낮은 수준의 게임 난이도, 체감형 인터페이스의 작은 사용범위와 변질한 사용법 문제라는 3가지 문제점에 대응하는 각각의 해결방안을 제시하였다. 체감형 게임 콘텐츠 개발 방법에 대한 논의가 꾸준히 지속됨으로서, 체감형 게임에 특화된 게임 디자인 방식 형성이 발달할 것이며, 차세대 게임으로서 게임 산업과 게임 문화의 성장에 긍정적인 역할이 가능할 것이다.

• Corrosion Science and Technology
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• 제16권4호
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• pp.183-186
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• 2017

Galvanic corrosion tests of Zn/steel couples were conducted in 1 M NaCl and $1M\;MgCl_2$ solutions to investigate the impact of magnesium ion on corrosion behavior of the couples. Two types of Zn/steel couples were used for measurements of open circuit potential (OCP) and galvanic current. From the results of OCP transient of Zn/steel couples, the corrosion potential in $1M\;MgCl_2$ was a more positive value than that in 1 M NaCl during the sacrificial dissolution of Zn. However, earlier increase of OCP of the couples in $1M\;MgCl_2$ solution indicates that the sacrificial dissolution rate of Zn in $1M\;MgCl_2$ was enhanced more than that in 1 M NaCl, agreeing with the results on transients of galvanic current. This result is due to that cathodic reaction on the steel surface of the Zn/steel couple was enhanced in $1M\;MgCl_2$ by the occurrence of hydrogen evolution reaction.

• The Journal of Asian Finance, Economics and Business
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• 제7권8호
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• pp.15-23
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• 2020

Based on the theoretical underpinnings of the agency theory and liquidity theory, the purpose of this study is to show how managers who want to enhance the performance of Pakistan's non-financial sector can use liquidity policy in relation to corporate governance. Nowadays, Pakistan is facing a severe liquidity crisis; this study contributes by examining the mediating role of liquidity on the link of corporate governance-performance. We use data from 63 firms from 2010 to 2018, excluding 17 outliers. To analyze the data, we use the Seemingly Unrelated Regression (SURE) model and nlcom-Stata test. Our findings support the mediating role of liquidity on the link between corporate governance and performance. In addition, the results show that corporate governance improves performance. Furthermore, the study supports a significant positive association of liquidity and performance. For robustness, we use two performance variables - return on assets (ROA) and Tobin's q (TQ) - where ROA represents full mediation and TQ indicates partial mediation. This study helps to use liquidity policy to strengthen the inside and outside dimensions of corporate governance mechanisms that improve the performance of firms. Overall, these findings suggest better disclosure, transparency, and solutions to auditing issues that add value to the firms.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.919-927
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• 2020

The study examines the influence of factors on customer satisfaction in hotel services in Thanh Hoa province of Vietnam. In terms of the tangible facilities of hotels, customers appreciate the availability and the full range of equipment and additional services, as the 3-to-5-star hotels in Thanh Hoa province are almost new, built in the last five years - 7 of 13 hotels were built in 2015. In the process of measuring the effect of factors on satisfaction in hotel services there, the researchers conducted exploratory factor analysis, reliability test, correlation and regression to confirm the relationships of factors. Based on a survey of 380 respondents, the test results showed that the proposed factors have positive impacts on consumer satisfaction; they are: perceived quality (including intangible and tangible elements), brand image, perceived value, and customer relationship management. In particular, intangible elements have the strongest influence on customer satisfaction, followed by tangible elements, brand image, perceived value, and finally, customer relationship management. In addition, the study found that foreigners and higher education customers tend to be more satisfied by the hotels than other groups, which helps to suggest important and appropriate solutions for hotel managers in Thanh Hoa province.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.581-589
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• 2020

Foreign factors play an important role in the socio-economic development of each country, in which foreign direct investment (FDI), foreign aid and exports of goods and services are always given top priority in undeveloped countries as well as developing countries. The purpose of this study is to examine the relationship between the various factors such as FDI, foreign aid, exports and economic growth in Vietnam. The empirical method employed secondary time-series data set during the period 1997-2018 to determine the impact of FDI, foreign aid and exports on economic growth in Vietnam by using a linear approach. For this study, data is collected from the World Bank and relevant agencies in Vietnam. An empirical model is built with a correlation and regression analysis between economic growth (GDP, current) and three independent variables (FDI, aid, exports of goods and services). The results show that the relationship between FDI (net inflows), aid, exports and GDP (current) has a positive effect at a 1% significance level. Based on these findings, the article recommends that Vietnam continues to seek effective solutions to maintain high economic growth rates by attracting FDI inflows, official development assistance (ODA), and increasing exports of goods and services.