• KIEAE Journal
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• 제6권2호
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• pp.3-10
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• 2006

This study assessed the visual performance of luminous environment by the lightshelf. The subject survey method was used and results are presented and analyzed. The lightshelf daylighting system was developed by LAEL at KH University and was applied on the window of a mock-up office. The questionnaire for assessing visual performance contains 9 questions with 7 grade bipolar scales. The experiment was conducted during the bright part of the day from noon to one thirty on June 7, 2006. The questionnaire for assessing visual performance contains 9 questions with 7 grade bipolar scales. During the experiment was carrying out, the work plane illuminance and luminous distribution at surrounding the windows was measured. The semantic differential rating data of experiment were analyzed by t-test and factor analysis using SPSS 12.0 statistics package. The visual performance of the lightshelf was more positive. The factors affecting the visual performance are task performance and visual comfort. The subjects were more comfortable in a room installed with lightshelves on both the task performance and the visual comfort aspect. Therefore, the application of sloped lightshelf daylighting system improves visual performance of luminous environment.

• 센서학회지
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• 제22권1호
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• pp.18-27
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• 2013

Real-time monitoring is one of the prime necessities in a weapon flight test that is required for the efficient and timely collection of large amounts of high-rate sampled data acquired by an event-trigger. The wireless sensor network is a good candidate to resolve this requirement, especially considering the inhospitable environment of a weapon flight test. In this paper, we propose a priority based multi-channel MAC protocol with CSMA/CA over a single radio for a real-time monitoring of a weapon flight test. Multi-channel transmissions of nodes can improve the network performance in wireless sensor networks. Our proposed MAC protocol has two operation modes: Normal mode and Priority Mode. In the normal mode, the node exploits the normal CSMA/CA mechanism. In the priority mode, the node has one of three grades - Class A, B, and C. The node uses a different CSMA/CA mechanism according to its grade that is determined by a signal level. High grade nodes can exploit more channels and lower backoff exponents than low ones, which allow high grade nodes to obtain more transmission opportunities. In addition, it can guarantee successful transmission of important data generated by high grade nodes. Simulation results show that the proposed MAC exhibits excellent performance in an event-triggered real-time application.

• Tribology and Lubricants
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• 제28권2호
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• pp.81-92
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• 2012

To product multi-grade oil like engine oil, a sort of mineral base oil is mixed with a fundamental additive liquid package and a polymer liquid as viscosity index improver in order to improve the lubricating property of oil. That is, engine oil is the mixture of more than two fluids. In this paper, it will be systematically organized the governing equation describing non-Newtonian thermo-hydrodynamic lubrication related with the mixture of incompressible fluids based on the principle of continuum mechanics. Then, in order to find how the thermal analysis effect on the bearing performance lubricated with the mixture of multi-fluids, it will be compared to the performances between the mixture of each liquid to be blended and multi-grade engine oil as a single fluid in a high speed journal bearing. It is found that, in the case of lower viscosity oil, the difference of pressure distribution between the above two cases turns out to be existed, even if the load capacity is same level.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.105-111
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• 2020

The organic Rankine cycle (ORC) and the Kalina cycle system (KCS) are being considered as the most feasible and promising ways to recover the low-grade finite heat sources. This paper presents a comparative exergetical performance analysis for ORC and Kalina cycle using ammonia-water mixture as the working fluid for the recovery of low-grade heat. Effects of the system parameters such as working fluid selection, turbine inlet pressure, and mass fraction of ammonia on the exergetical performance are parametrically investigated. KCS gives lower lower exergy destruction ratio at evaporator and higher second-law efficiency than ORC. The maximum exergy efficiency of ORC is higher than KCS.

• Journal of the Korean Wood Science and Technology
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• 제38권2호
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• pp.85-93
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• 2010

Japanese cedar has low density and poor mechanical performance. Manufacturing glue-laminated timber (glulam) is the best way to compensate for its poor mechanical performance. The Korean Standard (KS) confines outermost lamina of glulam to higher grade than E8, but the yield of higher than grade E8 from logs is only 6.5%. Therefore, the aim of this study is to investigate the possibility of non-Korean-Standard glulam in structural applications. Allowable stresses determined by both hand-calculation and Monte-Carlo simulation show a higher allowable stress than that of the KS-standard glulam of 6S-22B. In the Korean Standard (KS), knot characteristics are not taken into account. Japanese cedar has relatively small knots. We believe that the small knots in Japanese cedar contribute to a higher allowable stress than the KS-standard glulam would predict. The species classification of KS is required to be further subdivided into sub-species groups based on knot characteristics.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.425-427
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• 2022

신경교종의 등급은 생존과 관련된 중요한 정보로 종양 진행을 평가하고 치료 계획을 세우기 위해 치료 전 신경교종의 등급을 분류하는 것이 중요하다. 신경교종 등급의 분류는 주로 고등급 신경교종과 저등급 신경교종으로 나누는 방식을 주로 사용한다. 본 연구에서는 심층신경망 모델을 활용하여 촬영된 MRI 영상을 분석하기 위해 이미지 전처리 기법을 적용하고 심층신경망 모델의 분류 성능을 평가한다. 가장 높은 성능의 EfficientNet-B6 모델은 5-fold 교차 검증에서 정확도 0.9046, 민감도 0.9570, 특이도 0.7976, AUC 0.8702, F1-Score 0.8152의 결과값을 보여준다.

• 한국과학교육학회지
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• 제17권2호
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• pp.127-137
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• 1997

The purpose of this study was to assess elementary student's ability of measuring length, area, and volume and reading metric scales. The findings of this study were as follows. All students were successful in measuring without scale, regardless of grades. But they were less successful in measuring the task using standard and nonstandard scales. Especially, in measuring area, lower grade students were not able to perform the task using nonstandard instruments, but higher grade students were able to perform the task. Measuring area using grade paper was least successful for sixth graders. In measuring volume, students under fifth grade read the upper scale when using graduated cylinder. In measuring by direct comparison, students were more successful in measuring length than in measuring area and volume using given material. The use of given nonstandard material was successful for 4th, 5th, and 6th grade students. In measuring using metric scale, lower grade students did not pay attention to the zero of the scale, but just read the end point. Higher grade students considered both zero and end points.

• 치위생과학회지
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• 제15권2호
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• pp.182-189
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• 2015

본 연구는 치위생과학생의 실습특성에 따른 임상실습만족도와 임상수행경험과의 관계를 규명하기 위해 2014년 11월에서 12월까지 현장실습 경험이 있는 치위생(학)과 2~4학년에 재학 중인 480명을 대상으로 연구의 목적을 설명을 하고 동의한 자에 의해 조사를 실시하여 분석한 결과 다음과 같은 결론을 얻었다. 임상실습기관별 만족도에서는 저학년보다 고학년으로 갈수록 임상실습기관만족도(p<0.001)와 임상수행경험(p<0.001)에서의 만족도도 높은 것으로 나타났고, 전공에 대한 만족도도 비교적 높게 나타났다. 임상실습만족도와 임상수행경험은 기관별로는 치과병(의)원이, 실습기관 결정에서는 치과병(의)원일 경우 학교에서 결정할 경우 점수가 높게 나타났고(p<0.002), 실습기간은 종합병원이나 대학병원인 경우 '늘여야 한다'(p<0.001)가, 실습지도는 종합병원에서는 전담치과위생사일 경우(p<0.009)가 치과병(의)원에서는 기관장(p<0.010)이 점수가 높게 나타났다. 임상실습만족도와 임상수행경험에 영향을 미치는 요인으로는 전공만족(p<0.001), 실습기간(p<0.01)으로 나타났다. 학생들의 임상실습에 대한 만족도를 높이기 위해서는 임상실습기관별 특성을 고려하는 실습운영 시스템을 구성하고 교육을 전담하는 치과위생사로 하여금 능동적인 실습기간으로 운영될 수 있도록 하며 기관에서는 학교와의 지속적인 연계를 통해 끊임없이 교육내용을 개선 및 보완을 해야 할 것으로 생각된다.

• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.483-489
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• 2018

Recently proposed organic flash cycle (OFC) was shown to potentially improve power generation using low grade heat source. In this paper, a thermodynamic performance is carried out for a modified OFC employed double expansions. Effects of the selection of working fluid and the important system parameters such as the temperatures in flash evaporators on the system performance were extensively investigated. Results showed that the system performances are strongly influenced with the system parameters and selection of the working fluid, and the power generation can be increased compared to the basic OFC.

• 한국학교수학회논문집
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• 제4권2호
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• pp.61-74
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• 2001

The purposes of this study are to develop the mathematical performance assessment tasks and to apply them to the middle school students. And I also intend to know the students' inclination and learning attitude to mathematics. In order to satisfy this study, I developed the performance assessment tasks and the standard program of marking about the mathematical function and statistics for the first grade students at middle school. After examining the students' basic investigation, their inclination and learning attitude to mathematics, I applied these developed tasks to them After that I put both classes and performance assessment into operation in all 15 periods. I set up two classes of the first grade students (49 students) at J middle school in Kongju, Chungcheongnam-do as a model group. The results of this study are as follows: First, owing to the developed performance assessment tasks of function and statistics, the teachers can operate the assessment system as a process of teaching and learning. Second, because of the application of mathematical performance assessment tasks, we can change the students' inclination and learning attitude to mathematics affirmatively. And by using these tasks, we can help the students to think mathematically. In this way, the students will be able to realize the real value of mathematics and have a growing interest in mathematics through all these meaningful processes. Judging from this study, we can elevate the students' abilities of problem solving and reasoning and improve teaching-learning method by applying the performance assessment tasks to them. Thanks to these tasks, the students will be changed affirmatively in their inclination and learning attitude to mathematics. I think that these tasks are very good assessment method which can call forth curiosity and interest. Besides, they can also help the students realize the real value of mathematics.