• 대한수학교육학회지:학교수학
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• 제18권4호
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• pp.881-901
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• 2016

본 연구는 '시간, 거리, 속력'의 관계에 대한 학생들의 인식과 표현을 교수실험을 통하여 세밀하게 관찰한 연구이다. 이 과정에서 학생들의 '시간, 거리, 속력'의 관계에 대한 인식의 변화가 드러났으며, 학생들은 평균속력에 대하여 거리함수에서 구간의 양 끝점을 잇는 선분의 기울기라는 관점으로 인식하는 것 외에도 속력함수에서 사각형의 높이로 인식하여 '시간, 거리, 속력'을 이해하고 있음을 보여주었다. 이 과정에서 '거리=시간${\times}$속력'의 관계를 '거리=시간${\times}$평균속력'으로 확장하는 장면을 드러내었다. 본 연구는 제한된 소수 학생을 대상으로 교수실험을 진행하였지만, 학생들의 '시간, 거리, 속력'의 관계에 대한 인식과 표현의 변화 과정에 대한 관찰을 통하여 여러 시사점을 제시하였다. 이러한 연구 결과가 추후 미적분 학습 모델 구성을 위한 다양한 연구의 시발점이 되기를 기대해본다.

• 한국정밀공학회지
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• 제28권4호
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• pp.482-489
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• 2011

In practical design process, designer needs to find an optimal solution by using full factorial discrete combination, rather than by using optimization algorithm considering continuous design variables. So, ANOVA(Analysis of Variance) based on an orthogonal array, i.e. Taguchi method, has been widely used in most parts of industry area. However, the Taguchi method is limited for the shape optimization by using CAE, because the multi-level and multi-objective optimization can't be carried out simultaneously. In this study, a combined method was proposed taking into account of multi-level computational orthogonal array and TOPSIS(Technique for Order preference by Similarity to Ideal Solution), which is known as a classical method of multiple attribute decision making and enables to solve various decision making or selection problems in an aspect of multi-objective optimization. The proposed method was applied to a case study of the multi-level shape optimization of lower arm used to automobile parts, and the design space was explored via an efficient application of the related CAE tools. The multi-level shape optimization was performed sequentially by applying both of the neural network model generated from seven-level four-factor computational orthogonal array and the TOPSIS. The weight and maximum stress of the lower arm, as the objective functions for the multi-level shape optimization, showed an improvement of 0.07% and 17.89%, respectively. In addition, the number of CAE carried out for the shape optimization was only 55 times in comparison to full factorial method necessary to 2,401 times.

• 정보관리연구
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• 제43권3호
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• pp.117-137
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• 2012

한국의 전자정부 구축 현황을 살펴보고 전자정부를 통하여 거버넌스의 향상에 기여할 수 있는 방안에 대해 고찰해 보았다. 한국의 전자정부는 구현 수준에 있어 국제적 평가에서 상위권에 위치하는 것을 확인할 수 있었으나 전자정부 발전의 최종단계인 통합처리의 관점에서는 지속적인 개선 노력이 필요한 상황으로 평가되었다. 한국의 전자정부가 거버넌스의 향상에 어느 정도 기여하고 있는가를 평가하기 위해 공급자와 이용자의 관점에서 전자정부의 활용도를 평가하였으며 거버넌스와 관련된 기능의 제공 및 활용이라는 정성적인 관점에서 활용도를 평가해 보았다. 한국의 전자정부 활용도는 정량적인 관점에서 상당한 수준에 도달해 있으나 거버넌스의 향상에 기여할 수 있는 이용목적이라는 정성적인 관점에서는 여전히 개선의 여지가 있는 것으로 평가되었다. 위와 같은 평가에 기반하여 전자정부를 통한 거버넌스 향상을 위해 필요한 고려사항들을 제시하였다.

• 공학교육연구
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• 제8권4호
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• pp.20-30
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• 2005

본 연구의 목적은 공학 프로그램의 교육목표에 따라 학생의 학습 성과 성취도를 높일 수 있도록 학생포트폴리오 관리프로그램을 개발하는 데 있다. 학생 포트폴리오 관리 프로그램(SPMP: Student Portfolio Management Program)은 인증요건, 학생들의 학습자료, 학습과제와 그 결과물들을 테이터 베이스 체계를 통하여 관리할 수 있도록 개발하였다. 또한 학생 포트폴리오 관리 프로그램은 공학교육인증에 있어서 요청되는 요건들을 통계적으로 처리하여 종합적으로 제공할 수 있도록 개발하였다. 학생포트폴리오 관리 프로그램을 구성하는 3가지 주요 기능은 첫째, 학생 개인 이력관리 기능으로서 개인정보자료, 교육프로그램에 관련된 자료 등 다양한 입력 자료로 구성되며 둘째, 학생 인증요건 관리 기능으로서 학습 성과, 이수과목 성적 등 인증요건 평가항목으로 구축되며 셋째, 학습과제관리 기능으로서 학습과제 작성, 검색 그리고 과제제출 항목들로 구성된다. 학생 포트폴리오 관리 프로그램을 통한 체계적인 프로젝트 관리는 공학인증이 목표로 하는 사회가 요구하는 능력 향상 및 인재양성에 긍정적인 효과를 가져 올 수 있다. 또한 관리 프로그램에서 제공하는 지속적인 결과물의 기록 및 관리는 대상 학생들이 자신의 포트폴리오를 상시로 필요한 곳에 제출 할 수 있게 도움을 준다.

• 한국환경복원기술학회지
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• 제20권5호
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• pp.59-66
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• 2017

Preeminent water treatment plans are essential to preserve the water quality of aquatic biotopes. Previous studies have not been sufficient to provide cost-effective maintenance method since they focused only on the purification of deteriorated water that requires a continuous supply of clean water. This study proposes an economical method of water quality maintenance using water treatment media block constructed vertically using porous ceramics, zeolite, and river pebble. The water treatment media block does not require a separate purification area because it functions as a purifier within the ecological pond which can maximize the biotope area. To evaluate the performance of the water treatment media block, we longitudinally tracked the change of water quality indicators (pH, TDS, COND, DO, T-P, T-N, COD) suggested by Water Environment Standards, Ministry of Environment, Republic of Korea. We compared the water quality of one control (A: general ecological pond composition method of the laminated structure) and two experimental groups (B: a combination of aquatic plants and a water treatment media block, C: a water treatment media block only). As a result, we confirmed that the water treatment media block is an efficient and economical method to maintaining the water quality of the ecological pond for a long time. The water treatment media block will be a great help in providing a better aquatic biotope space for aquatic insects and fishes living in clear water.

• 한국건설관리학회논문집
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• 제16권2호
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• pp.3-11
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• 2015

산업 및 사회발전의 고도화를 통해 국내 도시는 주택 및 각종 시설이 개선된 반면, 농촌은 그에 크게 미치지 못하고 있다. 또한, 주민의 고령화로 인한 유지보수를 적기에 실시 못하는 문제나, 경제적으로 어려운 상황 속에서 제대로 된 공법, 기술, 재료를 이용한 개축 등을 하는 것을 기대할 수 없는 실정이다. 본 연구는 농촌주민의 고령화 및 농촌주거의 노후화에 따른 문제점에 대한 현황조사를 통해 지역실정에 적합한 농촌주거의 재생방안을 모색하였다. 그 결과, 주거양식은 한국의 전통가옥양식이 절반가량을 차지하고 있었으며, 서구식 주거양식의 농촌주택에 비해 상대적으로 주거수준이 열악한 것으로 나타났다. 구조형식은 순수구조와 복합구조가 각기 절반씩을 차지하고 있었으며, 그 중에서 한국의 전통가옥양식은 순수구조보다는 복합구조가 많았다. 이는 본래의 모습으로는 내구성능, 거주자의 용도 등의 기능을 충족시킬 수 없기 때문에 거주자에 의해 지속적인 변화가 계속되었기 때문인 것으로 사료된다. 이러한 문제점에 대해 농촌지역의 특성에 알맞는 농촌주거 개선이 필요하다.

• Structural Engineering and Mechanics
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• 제42권5호
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• pp.715-728
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• 2012

This paper deals with determining the fundamental frequency of tall buildings that consist of framed tube, shear core, belt truss and outrigger systems in which the framed tube and shear core vary in size along the height of the structure. The effect of belt truss and outrigger system is modeled as a concentrated rotational linear spring at the belt truss and outrigger system location. Many cantilevered tall structures can be treated as cantilevered beams with variable cross-section in free vibration analysis. In this paper, the continuous approach, in which a tall building is replaced by an idealized cantilever continuum representing the structural characteristics, is employed and by using energy method and Hamilton's variational principle, the governing equation for free vibration of tall building with variable distributed mass and stiffness is obtained. The general solution of governing equation is obtained by making appropriate selection for mass and stiffness distribution functions. By applying the separation of variables method for time and space, the governing partial differential equation of motion is reduced to an ordinary differential equation with variable coefficients with the assumption that the transverse displacement is harmonic. A power-series solution representing the mode shape function of tall building is used. Applying boundary conditions yields the boundary value problem; the frequency equation is established and solved through a numerical process to determine the natural frequencies. Computer program has been developed in Matlab (R2009b, Version 7.9.0.529, Mathworks Inc., California, USA). A numerical example has been solved to demonstrate the reliability of this method. The results of the proposed mathematical model give a good understanding of the structure's dynamic characteristics; it is easy to use, yet reasonably accurate and suitable for quick evaluations during the preliminary design stages.

• 지구물리와물리탐사
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• 제7권1호
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• pp.45-50
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• 2004

This paper describes a method of detecting formation boundaries, and permeable fractures, from frequency-domain Stoneley wave logs. Field data sets were collected between the depths of 330 and 360 m in well EE-4 in the Higashi-Hachimantai geothermal field, using a monopole acoustic logging tool with a source central frequency of 15 kHz. Stoneley wave amplitude spectra were calculated by performing a fast Fourier transform on the waveforms, and the spectra were then collected into a frequency-depth distribution of Stoneley wave amplitudes. The frequency-domain Stoneley wave log shows four main characteristic peaks at frequencies 6.5, 8.8, 12, and 13.3 kHz. The magnitudes of the Stoneley wave at these four frequencies are affected by formation properties. The Stoneley wave at higher frequencies (12 and 13.3 kHz) has higher amplitudes in hard formations than in soft formations, while the wave at lower frequencies (6.5 and 8.8 kHz) has higher amplitudes in soft formations than in hard formations. The correlation of the frequency-domain Stoneley wave log with the logs of lithology, degree of welding, and P-wave velocity is excellent, with all of them showing similar discontinuities at the depths of formation boundaries. It is obvious from these facts that the frequency-domain Stoneley wave log provides useful clues for detecting formation boundaries. The frequency-domain Stoneley wave logs are also applicable to the detection of a single permeable fracture. The procedure uses the Stoneley wave spectral amplitude logs at the four frequencies, and weighting functions. The optimally weighted sum of the four Stoneley wave spectral amplitudes becomes almost constant at all depths, except at the depth of a permeable fracture. The assumptions that underlie this procedure are that the energy of the Stoneley wave is conserved in continuous media, but that attenuation of the Stoneley wave may occur at a permeable fracture. This attenuation may take place at anyone of the four characteristic Stoneley wave frequencies. We think our multispectral approach is the only reliable method for the detection of permeable fractures.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.55.2-55.2
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• 2012

Intensive theoretical and experimental studies have been carried out at Korean Institute of Science and Technology (KIST) on controlling the bio absorbing rate of the Mg alloys with high mechanical strength through tailoring of electrochemical potential. Key technology for retarding the corrosion of the Mg alloys is to equalize the corrosion potentials of the constituent phases in the alloys, which prevented the formation of Galvanic circuit between the constituent phases resulting in remarkable reduction of corrosion rate. By thermodynamic consideration, the possible phases of a given alloy system were identified and their work functions, which are related to their corrosion potentials, were calculated by the first principle calculation. The designed alloys, of which the constituent phases have similar work function, were fabricated by clean melting and extrusion system. The newly developed Mg alloys named as KISTUI-MG showed much lower corrosion rate as well as higher strength than previously developed Mg alloys. Biocompatibility and feasibility of the Mg alloys as orthopedic implant materials were evaluated by in vitro cell viability test, in vitro degradation test of mechanical strength during bio-corrosion, in vivo implantation and continuous observation of the implant during in vivo absorbing procedures. Moreover, the cells attached on the Mg alloys was observed using cryo-FIB (focused ion beam) system without the distortion of cell morphology and its organ through the removal of drying steps essential for the preparation of normal SEM/TEM samples. Our Mg alloys showed excellent biocompatibility satisfying the regulations required for biomedical application without evident hydrogen evolution when it implanted into the muscle, inter spine disk, as well as condyle bone of rat and well contact interface with bone tissue when it was implanted into rat condyle.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.51-60
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• 2016

Consumers who use mobile applications for their skin care are increasing due to increasing interest in skin care and smart phone use. A survey was conducted to select popular skin care mobile applications to be installed in the smart phone targeting 1,000 men and women in South Korea who are interested in their skin care. Questioned items included skin care awareness and recognition, skin care type, and the intention of using skin health care mobile services. The respondents thought the best skin as 'Flawless skin (52.3%)'. Also, 'Skin trouble' and 'Skin aging' were their major concerns. 47.1% of the respondents used mobile skin care applications, and 56.6% intended to try new mobile skin care services. The results on interesting field of skin care showed significant difference depending on gender, marital status, and annual average household income. Moreover, the results on effort made for skin care showed significant difference depending on age, gender, and marital status. They wanted the functions such as 'Review on cosmetic products by brand (23.8%)', 'Self skincare method (16.8%)', 'Continuous monitoring service (16.2%)', 'Information on cosmetic products (13.4%)'. The result of this study would be reliable as basic material for skincare mobile service area. Further studies could be focused on developing application in accordance with needs and how it should be applied.