• 한국광물학회지
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• 제1권2호
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• pp.117-130
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• 1988

감포지역(甘浦地域)에서 산출(産出)되는 성질(性質)이 다른 시료(試料)들을 전자현미경(電子顯微鏡)에 의하여 그 형태적(形態的) 특징(特徵)을 관찰한 결과 몬모릴로나이트는 화산성물질(火山性物質) 즉 응회암기원(凝灰岩起源)임을 지시(指示)한다. 주사전자현미경(走査電子顯微鏡)에 의한 몬모릴로나이트의 형태적특징(形態的特徵)은 결정성장(結晶成長)에 필요한 가용공간(可用空間)의 유무(有無)에 따라 크게 영향을 받는 것으로 보이며, 가용공간(可用空間)이 충분한 경우엔 전형적(典型的)인 honeycomb 구조를 이루며 그와 반대인 경우에는 조밀하게 패킹된 판상(板狀)의 집합체(集合體)로 산출(産出)되는 경향을 보인다. 투과전자현미경(透過電子顯微鏡)으로 관찰된 결정형(結晶型)의 종류는 동일(同一)한 시료내에서 여러 가지가 관찰되나 불규칙한 엽상(葉狀)의 집합체(集合體)가 가장 우세하게 산출(産出)되며 판상(板狀)의 결정형(結晶型)이 흔히 관찰된다. 일반적으로 본 연구지역 중 죽전리(竹田里)의 효동리화산암류(孝洞里火山岩類)에서 산출되는 시료들보다 용동리(龍洞里)의 용동리응회암내(龍洞里凝灰岩內)에 배태(胚胎)된 시료에서 상대적(相對的)으로 판상(板狀)의 결정형이 우세하다.

• Ocean and Polar Research
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• 제38권2호
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• pp.139-148
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• 2016

The activity concentrations of $^{210}Po$ and $^{210}Pb$ within phytoplankton-zooplankton-anchovy-mackerel in the coastal water of the Jeju Island were determined to understand their distribution and bio-accumulation along the trophic level. In the surface water, the total activity concentrations of $^{210}Po$ and $^{210}Pb$ were $0.83{\pm}0.004mBq\;kg^{-1}$ and $1.27{\pm}0.03mBq\;kg^{-1}$. And the dissolved activity concentration of $^{210}Po$ and $^{210}Pb$ were $0.75{\pm}0.06mBq\;kg^{-1}$ and $1.22{\pm}0.09mBq\;kg^{-1}$ respectively. In the phytoplankton, the concentration factor (CF) of $^{210}Po$ and $^{210}Pb$ were $1.5{\times}10^5$ and $2.6{\times}10^4$ shows $^{210}Po$ is 5 times higher compared to $^{210}Pb$. The similar CF factor in the zooplankton of $^{210}Po$ was derived as $1.4{\times}10^5$. The CF of $^{210}Po$ in anchovy was increased twice compared to that in plankton. This is the evidence that there is $^{210}Po$ bio-magnification in the trophic level of plankton-anchovy. However the $^{210}Po$ activity concentration in the muscle tissue of mackerel was one-hundred times lower than that in anchovy. This reflects that in the trophic level of anchovy-mackerel, the bio-accumulation of $^{210}Po$ is decreased. The activity concentrations of $^{210}Po$ in the internal organs of anchovy and mackerel were 8 to 38 times higher than those in muscle tissues. In phytoplankton-zooplankton-anchovy, the CF of $^{210}Pb$ was decreased five times along the trophic level in order. In anchovy-mackerel it was decreased by 30-70%.

• Restorative Dentistry and Endodontics
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• 제37권1호
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• pp.24-28
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• 2012

Objectives: The aim of this study was to test the hypothesis, that the effectiveness of irrigation in removing smear layer in the apical third of root canal system is dependent on the depth of placement of the irrigation needle into the root canal and the enlargement size of the canal. Materials and Methods: Eighty sound human lower incisors were divided into eight groups according to the enlargement size (#25, #30, #35 and #40) and the needle penetration depth (3 mm from working length, WL-3 mm and 9 mm from working length, WL-9 mm). Each canal was enlarged to working length with Profile.06 Rotary Ni-Ti files and irrigated with 5.25% NaOCl. Then, each canal received a final irrigation with 3 mL of 3% EDTA for 4 min, followed by 5 mL of 5.25% NaOCl at different level (WL-3 mm and WL-9 mm) from working length. Each specimen was prepared for the scanning electron microscope (SEM). Photographs of the 3mm area from the apical constriction of each canal with a magnification of ${\times}250$, ${\times}500$, ${\times}1,000$, ${\times}2,500$ were taken for the final evaluation. Results: Removal of smear layer in WL-3 mm group showed a significantly different effect when the canal was enlarged to larger than #30. There was a significant difference in removing apical smear layer between the needle penetration depth of WL-3 mm and WL-9 mm. Conclusions: Removal of smear layer from the apical portion of root canals was effectively accomplished with apical instrumentation to #35/40 06 taper file and 3 mm needle penetration from the working length.

• 산업경영시스템학회지
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• 제22권50호
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• pp.105-125
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• 1999

The results of analysis on foreign exchange market, stock and financial market after January of 1997 are that foreign exchange market will be affected by stock and financial market volatility about 1999. This means that stock and financial market are more stable than foreign exchange market. This also is supported by ‘financial market forecast of 1999 in Daewoo Economic Research Institute’. After won/dollar (end of period) will be increasing in 1,430 at second quarter of 1999, this is to downward 1,200 fourth quarter of 1999. This is somewhat based on government's higher exchange rate policy. But, after yield of corporate bond is to 11.0% at first quarter of 1999, this will be stable to 10.2% at fourth quarter. During the first quarter of 1999, yield of corporate bond is to somewhat increasing through sovereign debt and public bonds, technical adjustment of interest rate. After this, yield of corporate bond will be stable according to stability of price, magnification of money supply, restucturing of firms. So, stock market is favorably affected by stability of financial market. But, the pension and fund of USA, i.e., long-term portfolio investment fund, are injected through international firm's management. It is included by openness of audit, fair market about foreign investors. Finally, Moody's strong rating on the won-denominated bonds suggest that Korea's sovereign debt ratings could be restored to an investment grade in the near future. It sequentially includes inflow of foreign portfolio investment fund, fall of won/dollar foreign exchange rate (appreciation of won) and stability of yield of corporate bond.

• 한국결정성장학회지
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• 제23권2호
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• pp.81-85
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• 2013

새로운 표면처리로서 TCF(thermal color fusion) 기술이 적용된 스와로브스키사의 패션 토파즈(passion topaz)의 코팅 층 성분과 적층구조를 파악하기 위해 ED-XRF와 TOF-SIMS 분석을 실시하였다. 더불어 감별특징 관찰을 위한 확대검사와 내구성 평가를 미스틱 토파즈(mystic topaz)와 비교 분석하였다. 그 결과, 패션 토파즈에서도 미스틱 토파즈에서 보이는 유사한 특징들이 확대검사를 통해 관찰되었고, TOF-SIMS에 의한 depth profile 분석 결과에서 토파즈 표면으로의 확산코팅과 다층구조 코팅이 되어있음을 알 수 있었다. 또한 패션 토파즈는 금속 원소간의 화학반응에 의한 코팅처리로 미스틱 토파즈 보다 화학약품에 대한 안정적인 특성과 높은 모스경도를 보였다.

• Clinical and Experimental Reproductive Medicine
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• 제27권1호
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• pp.99-105
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• 2000

Objective: The objective of this study was to compare results of the macroscopic one-layer vasovasostomy with those of microscopic one-layer vasovasostomy and to analyze the change of semen parameters according to the interval of vasal obstruction. Method and Materials: Between March 1987 and December 1997, we performed 121 vasovasostomies using modified one-layer technique with loupe magnification (macroscopic vasovasostomy) or microscope. Among the 68 could be followed post-operatively, 37 patients were treated by macroscopic technique with loupe, and 31 patients by microscopic technique. We compared rates of anatomical patency (sperm count above than $10{\times}10^{6}$/ml) and pregnancy of macroscopic vasovasotomy with those of microscopic vasovasostomy. Patency and pregnancy rates according to vasal obstructive interval were also examined. Results: The patency rates of macroscopic and microscopic technique were 86.5% and 87.1%, and pregnancy rates of macroscopic and microscopic technique were 64.9% and 67.7%. There was no statistical significance between these two methods (p>0.05). The pregnancy rates and sperm motility were decreased if more than 10 years had elapsed following vasectomy (p<0.05). Conclusion: We found little difference in success rates resulting from macroscopic and microscopic vasovasostomy and the former had the advantage of reduced cost and a lower operator skill level. In post-operative semen analysis, the sperm motility was the most probable factor associated with vasal obstructive interval.

• Imaging Science in Dentistry
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• 제33권1호
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• pp.35-41
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• 2003

Purpose: To aid in determining the volume of graft bone required before a maxillary sinus lift procedure and compare the alveolar bone height measurements taken by panoramic radiographs to those by CT images. Materials and Methods : Data obtained by both panoramic radiographs and CT examination of 25 patients were used in this study. Maxillary sinus volumes from the antral floor to heights of 5 mm, 10 mm, 15 mm, and 20 mm, were calculated. Alveolar bone height was measured on the panoramic images at each maxillary tooth site and corrected by magnification rate (PBH). Available bone height (ABH) and full bone height (FBH) was measured on reconstructed CT images. PBH was compared with ABH and FBH at the maxillary incisors, canines, premolars, and molars. Results: Volumes of the inferior portion of the sinuses were 0.55 ± 0041 ㎤ for 5 mm lifts, 2.11 ± 0.68 ㎤ for 10 mm, 4.26 ± 1.32 ㎤ for 15 mm, 6.95 ± 2.01 ㎤ for 20 mm. For the alveolar bone measurement, measurements by panoramic images were longer than available bone heights determined by CT images at the incisor and canine areas, and shorter than full bone heights on CT images at incisor, premolar, and molar areas (p<0.001). Conclusion: In bone grafting of the maxillary sinus floor, 0.96 ㎤ or more is required for a 5 mm-lift, 2.79 ㎤ or more for a 10 mm-lift, 5.58 ㎤ or more for a 15 mm-lift, and 8.96 ㎤ or more for a 20 mm-lift. Maxillary implant length determined using panoramic radiograph alone could result in underestimation or overestimation, according to the site involved.

• Structural Engineering and Mechanics
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• 제29권5호
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• pp.505-530
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• 2008

This paper proposes the application of active multiple tuned mass dampers (AMTMD) for translational and torsional response control of a simplified two-degree-of-freedom (2DOF) structure, able to represent the dynamic characteristics of general asymmetric structures, under the ground acceleration. This 2DOF structure is a generalized 2DOF system of an asymmetric structure with predominant translational and torsional responses under earthquake excitations using the mode reduced-order method. Depending on the ratio of the torsional to the translational eigenfrequency, i.e. the torsional to translational frequency ratio (TTFR), of asymmetric structures, the following three cases can be distinguished: (1) torsionally flexible structures (TTFR < 1.0), (2) torsionally intermediate stiff structures (TTFR = 1.0), and (3) torsionally stiff structures (TTFR > 1.0). The even distribution of the AMTMD within the whole width and half width of the asymmetric structure, thus leading to three cases of installing the AMTMD (referred to as the AMTMD of case 1, AMTMD of case 2, AMTMD of case 3, respectively), is taken into account. In the present study, the criterion for searching the optimum parameters of the AMTMD is defined as the minimization of the minimum values of the maximum translational and torsional displacement dynamic magnification factors (DMF) of an asymmetric structure with the AMTMD. The criterion used for assessing the effectiveness of the AMTMD is selected as the ratio of the minimization of the minimum values of the maximum translational and torsional displacement DMF of the asymmetric structure with the AMTMD to the maximum translational and torsional displacement DMF of the asymmetric structure without the AMTMD. By resorting to these two criteria, a careful examination of the effects of the normalized eccentricity ratio (NER) on the effectiveness and robustness of the AMTMD are carried out in the mitigation of both the translational and torsional responses of the asymmetric structure. Likewise, the effectiveness of a single ATMD with the optimum positions is presented and compared with that of the AMTMD.

• Structural Engineering and Mechanics
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• 제66권3호
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• pp.411-421
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• 2018

Although a rubber isolation cushion can reduce the dynamic response of a structure itself, it has little influence on the height of a sloshing wave and even may induce magnification action. Vertical baffles are set into a base-isolated Concrete Rectangular Liquid Storage Structure (CRLSS), and baffles are opened as holes to increase the energy dissipation of the damping. Problems of liquid nonlinear motion caused by baffles are described using the Navier-Stokes equation, and the space model of CRLSS is established considering the Fluid-Solid Interaction (FSI) based on the Finite Element Method (FEM). The dynamic response of an isolated CRLSS with various baffles under an earthquake is analyzed, and the results are compared. The results show that when the baffle number is certain, the greater the number of holes in baffles, the worse the damping effects; when a single baffle with holes is set in juxtaposition and double baffles with holes are formed, although some of the dynamic response will slightly increase, the wallboard strain and the height of the sloshing wave evidently decrease. A configuration with fewer holes in the baffles and a greater number of baffles is more helpful to prevent the occurrence of two failure modes: wallboard leakage and excessive sloshing height.

• 한국지진공학회논문집
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• 제15권3호
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• pp.1-9
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• 2011

자기부상열차가 중 저속 및 초고속 주행 시 차량의 주행특성 및 교량의 동적 응답 결과를 제시하고자 한다. 수직 자유도 및 회전 자유도를 포함한 10자유도 자기부상열차에 대한 운동방정식을 유도하고, 모드 중첩법을 이용하여 교량의 운동방정식을 구성하였다. 또한 제어 방법으로 UTM01제어기법을 적용하여 수치해석을 수행하였다. 해석 예제로 노면조도, 가이드웨이의 처짐비, 차량 속도 등이 교량의 처짐과 차량의 부상공극 및 여러 가지 변수에 미치는 영향을 파악하였다. 부상공극은 조도의 조건에 따라 그 차이가 확연히 드러나고 또한 자기부상열차의 속도가 증가함에 따라 부상공극이 증가함을 알 수 있었다. 그리고 자기부상열차가 중, 저속 주행 시에는 교량에 대한 영향이 미비하지만 초고속 주행 시 교량에 대한 동적확대계수가 큰 값을 보여주었다.