• 한국해양공학회지
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• 제16권2호
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• pp.10-20
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• 2002

본 논문에서는 바다의 자유표면에서 생성되는 항력에 대한 물리적 특성에 대한 연구가 기술되었다. 2차원 파장(Wave Field) 매개변수해석기법(Parametric Analyzing Technique)을 근거로 한 파경계층(Wave Boundary Layer : WBL)의 1차원 모델로서 항력계산과 파경계층의 특성을 추정하였으며 이론의 간략화(Simplifying)에 대한 연구에 주력하였다.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1813-1821
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• 2024

Beam shaping assembly (BSA) is a vital component in Boron Neutron Capture Therapy (BNCT) for obtaining epithermal neutron beams. Several feasible designs of BSA for accelerator-based BNCT (AB-BNCT) neutron source are carried out based on neutrons by bombarding a natural lithium target with 10 mA, 2.8 MeV proton beams. The calculation results demonstrate that a thickness of 45 cm is appropriate for general moderators referring to the therapeutic parameter of Advanced Depth (AD). A series of optimizations are performed and two results are confirmed: One is that employing the configuration of MgF₂ and FLUENTAL combined by 1:1 could improve the therapeutic rate (TR) of tumors at a depth of middle region, and the other one is that the TR of superficial tumors can be increased by adding a 5 cm thick boron-11 secondary moderator at the end of general moderators. As a result, an innovative conception of an adjustable moderator is recommended to BNCT. Compared to the MgF₂ moderator with a fixed thickness of 45 cm, the TR value can be improved by a maximum of 47.7 % by using the adjustable moderator. Furthermore, the configuration of adjustable moderator has been designed with regulation method for treating tumors of different depths.

• 천문학회보
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• 제42권1호
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• pp.37.1-37.1
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• 2017

We consider a magnetic dipole model of a pulsar and investigate general relativistic effects on electromagnetic radiation from the pulsar. The general relativistic modifications should be found applicable to many well-known issues in pulsar astronomy. Among other things, the modifications of Goldreich-Julian model and subpulse drift would be of significant interest and challenging issues. The electromagnetic fields in the pulsar magnetosphere are computed by solving Maxwell's equations defined in the strongly curved spacetime around the pulsar, hence containing the properties of strong gravitational effects. On top of these effects, we also investigate the effects from rotation and obliqueness of the pulsar to work out the general relativistic versions of Goldreich-Julian model and subpulse drift.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.41-43
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• 2004

Plasma polymerized para-xylene ($PP_PX$) deposited by plasma-enhanced chemical vapor deposition (PECVD) was used as the barrier layer on the polyethylene terephthalate (PET) substrate to improve lifetime of the flexible organic light-emitting diodes (FOLEDs). The $PP_PX$ barrier layer deposited on top of the PET substrate with plasma power of 30 W at deposition pressure of 0.2 torr showed transmittance spectra good enough to be applied in FOLED on PET substrates. FOLEDs with the $PP_PX$ barrier layer (barrier-FOLEDs) showed similar I-V and B-V characteristics to FOLEDs without the $PP_PX$ layer (control-FOLEDs). The lifetime of barrier-FOLED was two times longer than that of the control-FOLED. With $PP_PX$ passivation layers, lifetimes of both control and barrier-FOLEDs were improved by more than 4 times. These results show that PECVD deposited $PP_PX$ layers can be used as barrier layers for FOLEDs on plastic substrates as well as passivation layers for general OLEDs.

• 새물리
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• 제68권11호
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• pp.1231-1239
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• 2018

This study aimed at examining undergraduate students' writing about experiments related to the photoelectric effect and giving some implications for experiment education. Thus, this study analyzed 26 students' reports about three kinds of experiments: measuring Planck's constant, comparing the photocurrent and the photovoltage across the intensity of light, and comparing the photocurrent and the photovoltage across the frequency of light. In the measurements, less than 25% of the students expressed the data to the correct number of significant figures even though two-thirds of the students successfully obtained the data given in the manual. In terms of interpretation, the students were not aware of the physical meanings of the detailed parts in the graphs. Even though over 50% of the students drew a line relating photocurrent to voltage, no students compared the theoretical to the empirical data or made a judgment as to whether of not the background theory really fit the experiment. The research findings showed that insufficient knowledge and skills for physics inquiry may be an obstacle in performing the experiments well.

• 대한수학회보
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• 제58권6호
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• pp.1315-1325
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• 2021

In this paper, we firstly prove some general inequalities for the Neumann eigenvalues for domains contained in a Euclidean n-space ℝⁿ. Using the general inequalities, we can derive some new Neumann eigenvalues estimates which include an upper bound for the (k + 1)^th eigenvalue and a new estimate for the gap of the consecutive eigenvalues. Moreover, we give sharp lower bound for the first eigenvalue of two kinds of eigenvalue problems of the biharmonic operator with Navier boundary condition on compact Riemannian manifolds with boundary and positive Ricci curvature.

• 한국의학물리학회지:의학물리
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• 제8권1호
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• pp.69-79
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• 1997

뫼스바우어 분광법을 사용해서 다목적용으로 제조된 의학용 치료 연고제내에 포함된 자성물질 입자들의 성질들이 연고제내에서 안정되게 존재하고 있는 지를 연구하였다. 자성물질 내에 들어있는 $^{57}$ Fe 동위철 핵자들에 의해 나타나는 뫼스바우어 스펙트럼에 대해 분석한 결과들과 Fe$_3$O$_4$-${\gamma}$-Fe$_2$O$_3$ 체계에 대해 잘 알려진 분석결과들을 비교 연구하여 자성입자들의 구성상태를 규명할 수 있었다. 결과적으로 나타난 연고제내에 자성물질의 합성상태는 합성되지 않은 순수한 자성물 질만의 성분 분석과는 다른 결과를 나타내었다. 한편, 자성물질 입자의 크기 (~100$\AA$)가 매우 작음에도 불구하고 이들 입자들은 95K~300K 범위에서 초 상자성 형태의 뫼스바우어 스펙트럼 특성을 나타내지 않았다. 또한, 연고제를 방사성 살균한 후에도 자성물질 성분 구성에는 변화가 없었다.

• 한국과학교육학회지
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• 제32권8호
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• pp.1295-1317
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• 2012

There has been disagreement on the importance of definitions in science education. Yager (1983) believes that one crisis in science education was due to the considerable emphasis upon the learning of definitions. Hobson (2004) disagrees with physics textbooks that do not provide general definition on energy. Some textbooks explain that "there is no completely satisfactory definition of energy" or they can only "struggle to define it." In general, imprecise definitions in textbooks (Bauman, 1992) and inaccuracies in definition provided by teachers (Galili & Lehavi, 2006) may cause alternative conceptions. Besides, there are at least four challenges in defining physical concepts: precision, circularity, context and completeness in knowledge. These definitional problems that have been discussed in The Feynman Lectures, may impede the learning of physical concepts. A meta-study approach is employed to examine about five hundreds journal papers that may discuss definitions in physics, problems in defining physical concepts and how they may result in alternative conceptions. These journal papers are mainly selected from journals such as American Journal of Physics, International Journal of Science Education, Journal of Research in Science Teaching, Physics Education, The Physics Teachers, and so on. There are also comparisons of definitions with definitions from textbooks, Dictionaries of Physics, and English Dictionaries. To understand the nature of alternative conception, Lee et al. (2010) have suggested a theoretical framework to describe the learning issues by synthesizing cognitive psychology and science education approaches. Taking it a step further, this study incorporates the challenges in semantics and epistemology, proposes that there are at least four variants of alternative conceptions. We may coin the term, 'alternative definitions', to refer to the commonly available definitions, which have these four problems in defining physics concepts. Based on this study, alternative definitions may result in at least four variants of alternative conceptions. Note that these four definitional problems or challenges in definitions cannot be easily resolved. Educators should be cognizant of the four variants of alternative conceptions which can arise from alternative definitions. The concepts of alternative definitions can be useful and possibly generalized to science education and beyond.

• 새물리
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• 제68권12호
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• pp.1347-1355
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• 2018

본 연구의 목적은 과학중점학교의 교육과정을 분석하여 물리 관련 교과목(물리I, 물리II, 고급 물리, 실험 물리 등)이 어떻게 편성되어 있는지 알아보는 것이다. 이를 위하여 전국의 112개 과학중점학교 운영성과보고서에 제시된 교육과정을 분석하고, 교육과정 편성 이유와 특징을 추가로 알아보기 위하여 일부 학교에 대해 설문과 면담을 진행하였다. 주요 연구 결과는 다음과 같다. 첫째, 교과별 편성 단위를 살펴보았을 때, '과학'은 평균 6.7시간으로 가장 많았고, 물리I은 4.2시간, 물리II는 4.4시간으로 화학, 생명과학, 지구과학과 비슷한 수준이었다. 둘째, 물리I과 물리II는 2학년의 2개 학기에 각각 2단위씩 개설한 학교의 비율이 가장 많았으며, 집중이수로 개설한 학교는 물리I은 14개교, 물리II는 9개교였다. 셋째, 전문교과의 경우, 가장 많이 수업이 이루어지는 교과목은 '과제 연구'였고, 고급 물리를 개설한 학교는 7개교, 물리 실험을 개설한 학교는 34개교였다. 연구 결과를 바탕으로 2015 개정 교육과정의 적용을 고려하여 과학중점학교의 물리 관련 교과(물리학, 물리 실험)의 활성화를 위한 논의를 추가하였다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.64-64
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• 2003