• 공업화학
• /
• 제4권2호
• /
• pp.381-392
• /
• 1993

탄소수 10~18 범위에 있는 고급지방산 즉, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid 및 octadecanoic acid 등을 $SO_3$-dioxane complex로 ${\alpha}$-술폰화 한 다음, dodecanol-1에 에틸렌옥사이드를 5몰, 10몰, 20몰씩 부가시켜 제조한 POE 알킬 에테르류와 각각 반응시켜 15종의 올리고머 음이온성 계면활성제를 좋은 수율로 합성하였고, 이들 최종 합성화합물에 대하여 IR, NMR, 원서분석 등 기기분석을 행하여 분리확인하였다.

• 분석과학
• /
• 제30권1호
• /
• pp.1-9
• /
• 2017

Starch is a mixture of amylose (AMY) and amylopectin (AMP) which are different in physical properties such as molar mass (M), rms radius ($R_g$) and hydrodynamic diameter ($d_H$). The rheological and functional properties of starch are influenced by various factors including the molecular size, molar mass distribution (MD) and the concentration ratio of AMY and AMP. It is also important to analyze proteinaceous material in starch as they affect the flavor and texture of food to which starch is added. In this study, asymmetrical flow field-flow fractionation (AF4) was employed for separation and quantitation of AMY and AMP in starches (Amaranth, potato, taros and quinoa). AF4 was coupled with a multi-angle light scattering (MALS) and a refractive index (RI) detector for determination of the absolute M, MD and molecular structure. It was found that AMP has the M and $R_g$ ranging $3.7{\times}10^7{\sim}6.5{\times}10^8g/mol$ and 84 ~ 250 nm, respectively. Also the existence of branch was confirmed in higher M. In addition, proteinaceous material in starch was analyzed by AF4 coupled with a fluorescence detector (FS) after fluorescence-labeling. AF4-FS with fluorescence-labelling showed a potential for investigation on existence of proteinaceous material and the interaction between proteinaceous material and polysaccharide in starch.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2016년도 추계학술대회 논문집
• /
• pp.156-156
• /
• 2016

The effect of nitrogen doping on the mechanical and tribological performance of single-layer tetrahedral amorphous carbon (ta-C:N) coatings of up to $1{\mu}m$ in thickness was investigated using a custom-made filtered cathode vacuum arc (FCVA). The results obtained revealed that the hardness of the coatings decreased from $65{\pm}4.8GPa$ to $25{\pm}2.4GPa$ with increasing nitrogen gas ratio, which indicates that nitrogen doping occurs through substitution in the $sp^2$ phase. Subsequent AES analysis showed that the N/C ratio in the ta-C:N thick-film coatings ranged from 0.03 to 0.29 and increased with the nitrogen flow rate. Variation in the G-peak positions and I(D)/I(G) ratio exhibit a similar trend. It is concluded from these results that micron-thick ta-C:N films have the potential to be used in a wide range of functional coating applications in electronics. To achieve highly conductive and wear-resistant coatings in system components, the friction and wear performances of the coating were investigated. The tribological behavior of the coating was investigated by sliding an SUJ2 ball over the coating in a ball-on-disk tribo-meter. The experimental results revealed that doping using a high nitrogen gas flow rate improved the wear resistance of the coating, while a low flow rate of 0-10 sccm increased the coefficient of friction (CoF) and wear rate through the generation of hematite (${\alpha}-Fe_2O_3$) phases by tribo-chemical reaction. However, the CoF and wear rate dramatically decreased when the nitrogen flow rate was increased to 30-40 sccm, due to the nitrogen inducing phase transformation that produced a graphite-like structure in the coating. The widths of the wear track and wear scar were also observed to decrease with increasing nitrogen flow rate. Moreover, the G-peaks of the wear scar around the SUJ2 ball on the worn surface increased with increasing nitrogen doping.

• 지구물리와물리탐사
• /
• 제19권2호
• /
• pp.59-66
• /
• 2016

환경오염부지의 오염원은 대부분 전기비저항이란 고유물성과 상관관계를 보이기 때문에 전기비저항 탐사는 지중 환경오염조사에 매우 효과적인 방법이다. 이 연구에서는 폐기물 매립장 주변에서 전기비저항 탐사를 수행하여 매립장 주변 지역의 하부 지질구조를 규명하는 한편 침출수 존재 여부 및 영향 범위를 파악하였다. 또한, 주변 관측정의 수질분석 결과와 전기비저항 탐사의 연관성에 대해 분석하였다. 그 결과, 전기비저항 탐사는 수질분석 자료와 매우 높은 연관성을 보였으며, 시추조사 결과와도 상당히 일치하는 것을 확인하였다.

• 건축역사연구
• /
• 제3권1호
• /
• pp.123-142
• /
• 1994

This paper is a part of "A Case Study on The Dwellings and Settlement of Korean Immigrants to North-Eastern Province of China". Among various subjects from the study, this paper covers with the spaces and life style in the dwellings of Korean Immigrants. The purpose of this paper is to discribe how their dwelling culture has been moved and changed to a new environment. One rural village of Korean Immigrants named "Ch'ang-ts'ai" in Yen-pien Province was selected where we investigated more than 110 households. From the formal interview, I collect the data on the family structure, family economic state, dwelling spaces and its use, and dwelling facillities and furniture. From informal interview with key informants, I analyze how they have changed their dwelling spaces and life style since they moved here. Based on the analysis of the data, I conclude that major features of their dwelling and life style has been moved from Korean penninsula, specially from 'Hamkyong' Province where their ancestor has lived. This features are summarized as follows: a. Dwelling spaces and its functions are simillar to typical dwelling type of Hamkyong Province. b. They use "Chong-ji" for both a cooking space and a major living space. c. They have a life style of sitting on the floor. d. Bedrooms are differentiated with male and female. e. Most of their dwelling facillities and furniture arc different from those of Chinese in the same province. Since they immigrated, there has been some social changes which could influence on making their dwelling culture. But they have preserved their cultural identity on their dwellings and life style. So I suggest that the dwelling culture of a society would be seldom changed by immigration, as long as they will be given similar conditions such as the independent ethnic community, the same ecosystem, and economical autonomy.

• 한국항해학회지
• /
• 제19권1호
• /
• pp.49-69
• /
• 1995

What is the national competitive power\ulcorner What are the determinants of national competitive advantage\ulcorner In order to find these problems, this study was initiated theoretically through the international trade theory and international managerial strategic theory. The flow of studies, in connection with these competitive advantage, come into industries competitive advantage from national competitive advantage. It is understood that the flow of studies is based on the change of paradigm about the international industry environment. Today, the international industry environment has been changed into vigorous situation with the new trade system such as globalization, UR negotiation, WTO system instead of GATT. Among these environments, all enterprises in any industries should try to enhance their benefit, income profits and develop their management strategy, because it is essential for them to keep and make a profit in order to be competitive against all other rivaling enterprises. According to researchers and the ages of history, the concept and determinants of competitive advantage have been dissimiliar as followings. 1) Theory of absolute advantage : Absolute Product Cost. 2) Theory of comparative advantage : Comparative Product Cost. 3) Theory of reciprocal demand : the Reciprocal Demand Structure. 4) Theory of Hechsher-Ohlin : Factor Endowment. 5) Paradox of Leontief : the Quality of Factor Endowment. 6) Theory of technological gap : R & D. 7) Technological gap model : The Technological Gap. 8) Theory of the product life cycle : Product Life Cycle. 9) Christensen's study : Firm's character & manager's character. 10) Monopolistic Advantage Theories : Monopolistic Advantage 11) Electic theory : Ownership, location and internalization specific advantages. 12) Theory of value chain : Cost advantage, Differentiation, Focus. However all these theories have the limit of illustration regarding today's competitive situation, the Porter's theory shows well the determinants of competitive advantage with competitive strategy. Therefore, the analysis of the competitive advantage for maritime industry should be studied by the determinants of competitive advantage of nations

• 한국표면공학회지
• /
• 제46권5호
• /
• pp.187-191
• /
• 2013

Niobium nitride (NbN) films were deposited on AISI 304 stainless steels by inductively coupled plasma (ICP) assisted dc magnetron sputtering method at different ICP powers, and the effects of ICP power on the phase formation, mechanical and chemical properties of the films were investigated. X-ray diffraction analysis (XRD) and field emission scanning electron microscopy (FESEM) were used to analyze the crystal structure and micro-knoop hardness was used to measure the hardness of the films. Also, 3-D mechanical profiler and a ball-on-disk wear tester were used to measure the thickness of the films and to estimate wear characteristics, respectively. The thickness of the films decreased but their hardness increased with increasing ICP power, and it was confirmed that only cubic ${\delta}$-NbN(200) remained at high ICP power. At lower ICP powers, a mixture of the hexagonal ${\delta}^{\prime}$-NbN and cubic ${\delta}$-NbN phases was obtained in the films and the hardness decreased. The corrosion potential value increased gradually with increasing ICP power, but the changes of ICP power did not significantly influence the overall corrosion resistance.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2017년도 학술발표회
• /
• pp.295-295
• /
• 2017

본 연구에서는 2차원 수리모형을 이용하여 자연하천에 보가 없는 경우, 직선 보, 경사 보 3가지 경우로 적용하여 2차원 수리분석을 실시하여 상 하류 수리특성을 검토하여 향후 하천개설 및 하도 설계의 기초자료를 제공하고자 한다. 보의 배치가 하천에 미치는 영향으로 수리특성의 변화와 유속의 변화, 토사의 이동 등 하도 내 흐름 특성의 2차원 해석결과를 도출함으로써 하도 내 횡단구조물 설치에 따른 기초적인 자료를 제공하고자 한다. 보 설치로 인한 하천 주변 친수 공간 발달로 인한 여가시설, 이동편의를 위한 도로설치 등 공간조성 설계 시 기초자료로 활용가능 할 것이다. 연구대상 하도구간은 경주 시내를 통과하는 형산강의 남천합류부 2.7km 지점부터 경주시 천북면 모아리에 위치한 모아수위관측소까지 약 8.7km 구간이다. 연구대상 유역인근에 위치한 수위관측소는 경주, 모아 관측소가 있으며 수리해석을 위한 경계조건으로 활용하였다. 연구대상 구간의 상류 부근에 경주 북천이 합류하고 있으며 현재 월령보가 경사 방향으로 설치되어져 있다. 본 연구에서는 상류경계 입력자료 계획홍수량은 형산강하천기본계획보고서(2011)을 참고하였으며, 경주 금장대 부근 합류하는 북천의 계획홍수량은 북천하천기본계획보고서(2011)를 참고하였다. 하류 경계입력자료 계획홍수위도 형산강하천기본계획보고서(2011) 참고하여 2차원 수리특성을 분석하였다. 수문량에 따른 홍수위 변화특성을 분석한 결과 풍수량과 100년 빈도 홍수량에 대해서 직각보 최대수위가 높게 분석되었으며, 유속에 대해 분석한 결과 풍수량과 100년 빈도 홍수량에 대해서 직각보가 경사보보다 물넘이 부분에서 최대유속이 빠르게 분석되었다. 또한 보가 없을 경우와 풍수 시 흐름특성을 분석한 결과 유선방향이 현재의 경사보 방향과 일치하는 것으로 분석된다. 이상의 연구결과를 검토할 때, 직각보 상류에 자전거 교량을 건설할 때 최대 유속이 발생하는 위치에는 교량기초공이나 교각 부분의 보강이 필요할 것으로 판단된다. 둔치 주변 유속변화가 발생할 수 있으므로 수위와 유속을 동시에 고려한 친수시설을 설치할 필요가 있는 것으로 판단된다.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제58권2호
• /
• pp.161-185
• /
• 2019

이 연구에서는 중등 수학 교사와 예비교사들이 추론과 증명을 어떻게 이해하여 구성하는지를 탐색하였다. 연구 참여자들은 대부분 대수적인 증명을 시도하는데 이미 알고 있는 공식이나 식을 적용한 대수적 조작으로 답을 구하는 것에 그치며 주어진 문제에 내재된 수학적 구조를 통해 증명을 구성하지는 못하였다. 또한 참여자의 상당수가 대수적 식을 통한 증명만을 완전한 증명으로 판단하였으며 대부분은 기존에 접하지 못했던 새로운 문제유형에서 추론 및 증명구성을 완성하지 못하는 것으로 나타났다.

• Earthquakes and Structures
• /
• 제22권6호
• /
• pp.539-548
• /
• 2022

Steel plate shear walls (SPSWs) are one of the most important and widely used lateral load-bearing systems. The reason for this is easier execution than reinforced concrete (RC) shear walls, faster construction time, and lower final weight of the structure. However, the main drawback of SPSWs is premature buckling in low drift ratios, which affects the energy absorption capacity and global performance of the system. To address this problem, two groups of SPSWs under cyclic loading were investigated using the finite element method (FEM). In the first group, several series of circular rings have been used and in the second group, a new type of SPSW with concentric circular rings (CCRs) has been introduced. Numerous parameters include in yield stress of steel plate wall materials, steel panel thickness, and ring width were considered in nonlinear static analysis. At first, a three-dimensional (3D) numerical model was validated using three sets of laboratory SPSWs and the difference in results between numerical models and experimental specimens was less than 5% in all cases. The results of numerical models revealed that the full SPSW undergoes shear buckling at a drift ratio of 0.2% and its hysteresis behavior has a pinching in the middle part of load-drift ratio curve. Whereas, in the two categories of proposed SPSWs, the hysteresis behavior is complete and stable, and in most cases no capacity degradation of up to 6% drift ratio has been observed. Also, in most numerical models, the tangential stiffness remains almost constant in each cycle. Finally, for the innovative SPSW, a relationship was suggested to determine the shear capacity of the proposed steel wall relative to the wall slenderness coefficient.