• Computers and Concrete
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• 제32권2호
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• pp.119-138
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• 2023

Concrete carbonation is a prevalent phenomenon that leads to steel reinforcement corrosion in reinforced concrete (RC) structures, thereby decreasing their service life as well as durability. The process of carbonation results in a lower pH level of concrete, resulting in an acidic environment with a pH value below 12. This acidic environment initiates and accelerates the corrosion of steel reinforcement in concrete, rendering it more susceptible to damage and ultimately weakening the overall structural integrity of the RC system. Lower pH values might cause damage to the protective coating of steel, also known as the passive film, thus speeding up the process of corrosion. It is essential to estimate the carbonation factor to reduce the deterioration in concrete structures. A lot of work has gone into developing a carbonation model that is precise and efficient that takes both internal and external factors into account. This study presents an ML-based adaptive-neuro fuzzy inference system (ANFIS) approach to predict the carbonation depth of fly ash (FA)-based concrete structures. Cement content, FA, water-cement ratio, relative humidity, duration, and CO2 level have been used as input parameters to develop the ANFIS model. Six performance indices have been used for finding the accuracy of the developed model and two analytical models. The outcome of the ANFIS model has also been compared with the other models used in this study. The prediction results show that the ANFIS model outperforms analytical models with R-value, MAE, RMSE, and Nash-Sutcliffe efficiency index values of 0.9951, 0.7255 mm, 1.2346 mm, and 0.9957, respectively. Surface plots and sensitivity analysis have also been performed to identify the repercussion of individual features on the carbonation depth of FA-based concrete structures. The developed ANFIS-based model is simple, easy to use, and cost-effective with good accuracy as compared to existing models.

• 한국조리학회지
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• 제8권3호
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• pp.39-56
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• 2002

This is the study to stir up importance in bakery and to present evaluation of menu goods in barkery of tourist hotels. In order to achieve the purpose of this paper, it is gone ahead of the literature review including the previous research on the manu goods evaluation of tourist hotels. The major field research is to build a frame of the paper and present the model to release my humble theory. The limitation of the study was to make much of literature basis due to insufficient previous research on the issue. This is an unprecedented study on bakery department in tourist hotels in Korea thus no research model was unavailable for cross reference or comparative research. The evaluation of bakery menu good is directly related to the satisfaction of tourist hotels bakery consumers and we need a substantial managerial development method of bakery menu goods. This study has two goals in line with the purpose of investigation, that is to say, by understanding vital statistics of consumer and influence factor were created, and finally the factors and consumers and professional worker identified. The study would be framed into 5 parts like introduction, literature review, inquiry a plan and analysis method, consequence and discussion & conclusion. After the exploitative research, the study was approached to make findings through the questionnaires designed to find the relationship factor between consumer's evaluation and professional worker's evaluation of bakery menu goods in tourist hotels.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.436-437
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• 2011

Before 1970s, 154kV substations in Korea were built in outdoor steel structure types only. In early 1970s, Germany developed GIS and the first indoor GIS type substation was built in Korea in 1980. In 1998, 154kV indoor type substations were standardized into regular type and urban type which applied steel frames to structures. In 2002, this was re-standardized into five different types in detail. In 2009, 154kV compact substation design was developed and standardized and saved about 20% of the construction cost with new technology and methods. Compact substations were classified into three types ; urban type, multi-function type, and regular type. The first urban type compact substation, Jang-ki substation, was built in Kimpo in June, 2010. This paper would present the standard model of 154kV compact substation and the way of improving facilities for the first compact substation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.320-320
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• 2010

In the case of existing ultrasonic motors, they have characteristics such as outstanding response speed, speed and high efficiency. However, it's very hard to use practically them as small motors due to complicated structure and expensive cost. This paper proposed v-type ultrasonic linear motor. Stator of the motor is composed of thin elastic body and four ceramics attached to upper and bottom areas of the body. The ceramics have each direction of polarization. When two harmonic voltages which had $90^{\circ}$ phase difference were applied to the ceramics, the symmetric and anti-symmetric displacements were generated at the tip to make the elliptical motion. To find out a model that generates maximum displacement at contact tip, FEM program was used with change of leg-angle. In addition, optimal model was chosen by considering magnitude and shape of displacement according to change of frequency.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.260-263
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• 2002

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in $45^{\circ}$ Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ was shown in the range of about ${\leq}{\pm}5$ Oe.

• 한국태양에너지학회 논문집
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• 제33권2호
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• pp.64-69
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• 2013

According to the Fourth Assessment Report of Intergovernmental Panel on Climate Change(IPCC) Working Group III, climate change is already in progress around the world, and it is necessary to execute mitigation in order to minimize adverse impacts. This paper suggests future climate change needs, employing IPCC Special Report on Emissions Scenarios(SRES) to predict temperature rises over the next 100 years. This information can be used to develop sustainable architecture applications for energy efficient buildings and renewable energy. Such climate changes could also affected the present supplies of renewable energy sources. This paper discusses one recent Fourth Assessment Report of IPCC (Mitigation of Climate Change) and the Hadley Centre climate simulation of relevant data series for South Korea. Result of this research may improve consistency and reliability of simulation weather data or climate change in order to take advantage of SRES and PRECIS QUMP. It is expected that these calculated test reference years will be useful to the designers of solar energy systems, as well as those who need daily solar radiation data for South Korea. Also, those results may contribute zero carbon and design of sustainable architecture establishing future typical weather data that should be gone ahead to energy efficient building design using renewable energy systems.

• 한국전기전자재료학회논문지
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• 제24권9호
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• pp.733-738
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• 2011

A novel design of a simple square-frame USM (ultrasonic motor) was proposed. The stator of the motor consists of a square-frame shape elastic body and four rectangular plate ceramics. The four ceramics were attached to inner surfaces of the square frame elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90 degree phase difference voltage were applied to the ceramics on vertical surfaces. To find a model that generates elliptical motion at outside of the stator, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As result, the model EL10EH3ET0.5CL4 which generates the maximum elliptical displacement was chosen by analyzing the resonance mode according to changes in frequency.

• 한국과학교육학회지
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• 제32권3호
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• pp.428-445
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• 2012

The objective of this study is developing an instrument for investigating views of the respondents on nature of science(NOS) by using experienced scientific knowledge, atomic model. It consists of total six questions and 36 detail items, and each question is reflected the aspects of different NOS which are 'recognition on the model', 'tentativeness of scientific knowledge', 'subjectivity in science', 'use of inference and imagination', 'myths of the scientific method', and 'comparison between science and art'. Particularly, 'comparison between science and art' is addressed almost for the first time in this questionnaire. In the class environment almost not to teach nature of science linking with concrete scientific knowledge, to inquire how the students recognize nature of science, relating to experienced scientific knowledge through this questionnaire will give the data of scientific knowledge based recognition on the nature of science and an important implication for nature of science teaching with concrete scientific knowledge. Developing processes have gone through four steps. In first step, we chose aspects of NOS and developed questions and details. In second step, we tested the draft into fifteen science teachers and, reflecting their opinions, corrected the form and contents of questionnaires. In third step, we tested the questionnaire included writing section for expressing thoughts of the respondents into 55 students in science high school and checked index of coincidence between Likert and open-ended responses which shows 88.2% degree of consensus. Furthermore, to identify the feature of using concrete scientific knowledge we applied this and views on science and education questionnaires together into six university students. We performed final test to 68 university students and measured Cronbach's, and ultimately completed final questionnaire in last step.

• 한국정보시스템학회지:정보시스템연구
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• 제17권2호
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• pp.95-112
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• 2008

The development of the Information Technology(IT) has brought enormous change to the human life, not even only to the politics, economy, society, and cultures, but all the way through the people's consciousness and cultural patterns. However, the information society resulted information inequality issues and especially to those disabled people, who have more difficulties on the technology adaptation, the "digital divide" symptom is significantly found. At present the rapid development of IT has gone beyond the level of the information society and it is accelerating the ubiquitous society that will combine people, computers, and all objects into one. And during the time of ubiquitous the "digital divide" will still exist. This research is focused on the digital divide of disabled people that were insufficiently covered in the research of digital divide and ubiquitous. From the empirical study of the effect that the disabled contributes on the service usability in U-City, the factors of background of the digital divide, and the difference of such factors in types of sex, ages, disabled types, and disabled class, and finally how the ubiquitous divide of the disabled affects have been researched. Based on the proposed study model and by analyzing the model by structural equation, following resulted was gained. (1) With the TAM (TAM : Technology Acceptance Model), which is commonly used in the studies of IT devices and services, the digital divide of the disabled cases cannot be identified sufficiently since it is not eligible for Using Intention of U-City Services. (2) In case of the disabled, the mental factors like willingness to overcome the impediment and accessibility like environment to meet the information services and ability to access the services are more effective on Using Intention of U-City Services rather than TAM.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2006년도 정기학술발표대회 논문집
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• pp.467-470
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• 2006

모든 건설공사의 기초를 이루는 토공사는 건설기계의 사용으로 오늘날까지 많은 발전을 이루어 왔으나, 공기단축 및 원가절감에 있어 중요한 요소인 토공장비의 적정한 조합시공방안이 체계적으로 정립되어 있지 않고 경험에 의존하여 수행되는 상태로 관련분야에 대한 체계적인 연구가 필요한 실정이다. 합리적인 기계화 토공은 공사에 투입될 장비의 성능 및 특성, 공사의 종류, 규모 및 주위의 여건 등을 사전에 철저히 파악해야 하며, 사용 가능한 몇 가지 규격의 장비를 선정하여 최적조합시공을 계획해야 한다. 이에 본 연구에서는 시스템 다이내믹스 기법을 활용하여 토공작업의 여러 단계 중 기계화 토공장비의 굴착 후 적재 및 운반단계를 대상으로 토공장비의 최적조합시공에 의한 토공량 산정 모형을 구축한다. 이 연구의 결과로 도출되는 토공장비의 최적조합시공모형은 토공계획을 담당하는 관리자가 토공장비의 선정에 있어 최단시간에 합리적인 판단을 하게 해줄 것으로 기대된다.