• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.112-116
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• 2013

Surface modification of montmorillonite (MMT) with 3-glycidoxypropyl trimethoxysilane (3GTO) in mild methanol/water mixture has been investigated in detail. The influence of reaction conditions (including silane concentration in feed, reaction time and reaction temperature) on the grafting amount and yield of silane, and further on the grafting pattern of silanes was studied by thermogravimetric analysis, elemental analysis, X-ray diffraction (XRD) and BET. Higher silane concentration, longer reaction time and higher reaction temperature are all benefit to higher grafting amount. When the grafting reaction was performed with 3 mmol/g silane concentration, at $90^{\circ}C$ for 24 h, the grafted amount and yield of silane reached 1.4443 mmol/g and 30%, respectively. Based on the XRD and BET data analysis, a speculation that the grafting pattern of silanes was concentration dependence was proposed.

• 한국수학교육학회지시리즈A:수학교육
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• 제60권1호
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• pp.61-76
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• 2021

본 연구는 수학 예비교사들이 과제의 인지적 노력 수준 변형에서 겪는 오류와 어려움을 분석하여, 수학 과제 변형과 관련한 수학 예비교사 교육에 유의미한 시사점을 제공하는 것을 목적으로 한다. 이를 위해 24명의 수학 예비교사들을 대상으로 수직이등분선의 성질에 대한 추론 과제를 높은 수준과 낮은 수준으로 변형하는 활동과 이에 대한 반성 및 수정 기회를 제공하였다. 변형 과제를 중심으로 예비교사들이 과제의 수준 변형에서 겪는 오류와 어려움을 분석한 결과, 과제 수준의 판단 관점에서 PNC와 PWC 과제의 구분에 제한된 이해를 보였으며, 과제의 외형적인 요소에 의존하는 간섭 현상을 확인하였다. 과제 수준의 변형 관점에서 예비교사들은 과제의 목표와 수직적 위계를 간과하거나 변형 유형의 편향성을 보였다. 한편 예비교사들은 반성 및 수정 활동을 통해 자신들의 변형 과제의 오류를 인식하고 개선할 수 있었으며, 도구의 범주를 Geogebra를 포함한 공학적 도구로 확장하는 모습을 보여주었다.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2006년도 추계학술발표대회 논문집
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• pp.144-148
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• 2006

Kitchen space is one of the most dangerous places for the elderly. Modification of kitchen space for improving safety and independence for older residents is very important factor for aging -in-place. The purpose of this study wes to identify the current situation and modification of kitchen space by elderly-headed household. The sample included 108 respondents over the age 65 who consisted of elderly-couple or single person household with homeownership in Seoul. The data were analyzed by descriptive statistics. Based on the findings of the study, the present incidence and recognition of future need in kitchen modification were identified. Changes in kitchen space made tended to be nonstructural or relatively inexpensive items. In conclusion, this study suggests several ideas for improving current physical problems of kitchen space to support daily living of older residents.

• 산업기술연구
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• 제17권
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• pp.183-189
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• 1997

The computation of the flow around a supercritical airfoil with a divergent trailing edge(DTE) modification(DLBA 243) is compared to that of original supercritical airfoil(DLBA 186). For this computation, Reynolds-Averaged Navier-Stokes equations are solved with a linearized block implicit ADI method and a mixing length turbulence model. Results show the effects of the shock and separated flow regions on drag reduction due to DTE modification. Results also show that DTE modification accelerates the boundary layer flow near the trailing edges which has an effect similar to a chordwise extension that increases circulation and is consistent with the calculated increase in the recirculation region in the wake. Airfoil with DTE modification achieves the same lift coefficient at a lower incidence and thus at a lower drag coefficient, so that lift-to-drag ratio is increased in transonic cruise conditions compared to the original airfoil. The reduction in drag due to DTE modification is associated with weakening of shock strength and delay of shock which is greater than the increase in base drag.

• Molecules and Cells
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• 제19권2호
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• pp.157-166
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• 2005

Transfer RNA (tRNA) is a key molecule to decode the genetic information on mRNA to amino aicds (protein), in a ribosome. For tRNA to fulfill its adopter function, tRNA should be processed into the standard length, and be post-transcriptionally modified. This modification step is essential for the tRNA to maintain the canonical L-shaped structure, which is required for the decoding function of tRNA. Otherwise, it has recently been proposed that modification procedure itself contributes to the RNA (re)folding, where the modification enzymes function as a kind of RNA chaperones. Recent genome analyses and post-genome (proteomics and transcriptomics) analyses have identified genes involved in the tRNA processings and modifications. Furthermore, post-genomic structural analysis has elucidated the structural basis for the tRNA maturation mechanism. In this paper, the recent progress of the structural biology of the tRNA processing and modification is reviewed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 추계학술대회 논문집
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• pp.121-125
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• 1991

In order to minimize fixing error of workpieces, prismatic and cylindrical types. Modification Rule by Indexing Table and Modification Rule by NC Program are developed for machining centers by using touch trigger probes. The Modification Rule by Indexing Table means the alignment of workpiece to NC program through degree of freedoms of indexing table. The Modification Rule by NC Program is the alignment of NC program to workpiece set-up condition via the generation of NC program. A postprocessing module is also developed for generating NC-part Program (User Macro) to compensate for Machining errors in end milling and boring processes. Developed methods are verified by experiments.

• 한국기계가공학회지
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• 제10권4호
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• pp.38-43
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• 2011

Industrial reducer is in general use to Deck Crane. High-precision and high-efficient reducer is minimized the power-loss and energy-loss of a machine. So it contribute the price reduction and life extension. Reducer is usually using the Planetary gear reducer. Planetary gear reducer is composed the sun gear, planet gear, internal gear and casing. Industrial reducer's wear and breakage have a short-life. To solve this problem, it is using the profile-shifted-gear or tooth modification. This study was carried out the effect of addendum modification coefficient on tooth fillet bending strength to planetary reducer. Tooth fillet bending stress is calculate. And all parameter were expressed the function of addendum modification coefficient. And then stress concentration factor of tooth fillet curve was express the function of addendum modification coefficient using comparison between theory and finite element analysis.

• 한국항해학회지
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• 제25권4호
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• pp.461-469
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• 2001

The purpose of this paper is the optimum modification of dynamic characteristics of stiffened plate structure including the number of stiffener. This paper shows the optimum structural modification method by dynamic sensitivity analysis and quasi-least squares method and considers it's validity. In the method of the optimization, finite element method, sensitivity analysis and optimum structural modification method are used. The change of natural frequency and total weight are made to be an objective function. Thickness of plate, the number of stiffener and cross section moment of stiffener become a design variable. The dynamic characteristics of stiffened plate structure is analyzed using finite element method. Next, rate of change of dynamic characteristics by the change of design variable is calculated using the sensitivity analysis. Then, amount of change of design variable is calculated using optimum structural modification method. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate structure including the number of stiffener.

• 전자공학회논문지B
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• 제32B권5호
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• pp.788-797
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• 1995

In this paper, a variable time-scale modification using SOLA(Synchronized OverLap and Add) is proposed, which takes into consideration the different time-scaled characteristics of voiced and unvoiced speech, Generally, voiced speech is subject to higher variations in length during time-scale modification than unvoiced speech, but the conventional method performs time-scale modification at a uniform rate for all speech. For this purpose, voiced and unvoiced speech duration at various talking speeds were statistically analyzed. The sentences were then spoken at rates of 0.7, 1.3, 1.5 and 1.8 times normal speed. A clipping autocorrelation function was applied to each analysis frame to determine voiced and unvoiced speech to obtain respective variation rates. The results were used to perform variable time-scale modification to produce sentences at rates of 0.7, 1.3, 1.5, 1.8 times normal speed. To evaluate performance, a MOS test was conducted to compare the proposed voiced/unvoiced variable time-scale modification and the uniform SOLA method. Results indicate that the proposed method produces sentence quality superior to that of the conventional method.

• 기본간호학회지
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• 제8권2호
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• pp.234-243
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• 2001

Purpose : To investigate the effects of exercise combined with behavior modification therapy on the degree of obesity. blood lipid level and self-esteem in obese middle aged women. Method : 18 obese middle-aged women volunteers with a BMI over 30% were assigned to exercise combined with behavior modification therapy (n=9) or to a control group(n=9). For the intervention the experiment group used walking outdoors as excercise and behavior modification therapy for 12 weeks. Result Body weight, BMI, TC, TG, LDL-C, and % TC/HDL-C were significantly decreased in experimental group. Changes in HDL-C and self-esteem were significantly increased in the experimental group. Conclusion : This study provides evidence that regular exercise combined with behavior modification is effective in changing the degree of obesity, blood lipid level and self esteem in obese middle-aged women over 12 weeks.