• The Journal of the Convergence on Culture Technology
• /
• v.5 no.1
• /
• pp.385-388
• /
• 2019

Considering spherically symmetric spacetimes embedded in a 5-dimensional static Lorentzian manifold, within the large distance limit of DGP model, we study null geodesic equations. We discuss possible relations of particles following the geodesics with the gravitational waves detected recently, in comparison with the electromagnetic waves propagaing in these brane spacetimes.

• Journal of The Korean Association For Science Education
• /
• v.19 no.1
• /
• pp.62-77
• /
• 1999

Idealization has an important role in the process of learning as well as in physics research. The purpose of this study was to survey students' and science teachers' recognition of the ideal conditions involved in the process of problem solving and of explaining the natural phenomena. The instrument for probing the understanding of the ideal conditions in the domains of force, electricity and heat was administered to general high and science high school students and science teachers. The framework of responses composed of three categories. The first category is "idealized conditions relevant to problem", the second "not relevant idealized conditions", which has more delicate subcategories of general/ irrelevant conditions, simple statement of formula/ law, repeating problems, uncorrect explaining/ describing conditions, and the last "no responses". The results of analysis showed that the majority of the subjects well understood the various ideal conditions, especially for science high school students. But some of them could not differentiate the ideal condition from the general conditions, or they simply repeat the problem situation or the formula. The understanding of idealization is different by the domains of physics. We discovered that the misconceptions about the ideal conditions in various physical phenomena and revealed some interconnection of researches in the fields of misconception and the ideal condition.

• Korean Journal of Optics and Photonics
• /
• v.24 no.5
• /
• pp.245-250
• /
• 2013

The Wiener-Khinchin theorem, which means that the autocorrelation function of a signal corresponds to the power spectrum of the signal, is very important in signal processing, spectroscopy and telecommunications engineering. However, because of needs for some relatively expensive equipments such as a correlator and the signal processing system, its demonstration in most undergraduate class is not easy so far. Recently, digital oscilloscopes whose functions can be replaced foresaid equipments are marketed with development of digital engineering. In this paper, a simple demonstration of the theorem is given by a digital storage oscilloscope and a personal computer with its theoretical background. The reason that deals again with this theorem which has been introduced in 1930 is that it has been not well informed yet to us and theoretical background of the demonstration is directly introduced from its driving process. Through deriving process of the theorem, some extended physical meanings of the impedance, power, power factor, Wiener spectrum, linear system response and, furthermore, basic idea of the Planck's quantization in the black body theory reveal themselves naturally. Hence it can be referred to lectures in general physics, modern physics, spectroscopy and material characterization experiment.

• Journal of The Korean Association For Science Education
• /
• v.9 no.1
• /
• pp.53-67
• /
• 1989

General Physics CAI Program was developed for university science and engineering student. The program was restricted in the field of mechanics and was mainly aimed for individual tutorial. This project was supported by Government. Department of Education, physics attending their general physics classes in university. The program was written in BASIC and constructed by frame, 4 professors and 6 graduate students were involved in the project. Summary of this study is as follows. 1. The theory of CAI was illuminated from a new point of view to enhance usefullness of CAI. Also the structure of frame type CAI was studied. 2. The program was developed as follows 1) The program consisted of main program, pretest routine, tutorial routine, final test routine, and several other routines for program control. Whole program was written in BASIC. 2) 20 problems for pretest, 90 problems and subsequent hints and solutions for tutorial, 20 problems for final test were developed. 3) According to student's pretest result, tutorial course was routed through several different courses which contain different number of problems 4) The expected rate of achievment for final test was set to 75%. 5) Data of students response to problems including number of tries and time used were recorded for the purpose of achievment analisys 3. 22 students went through whole course and the results were as follows. 1) Pretest marks were widly distributed from 20 points to 100. It means that achievement of high school physics course were not enough. 2) Throughout tutorial course, students who had got higher mark in pretest answered correctly in the first trial at a higher rate of 78 %. Overall rate of correct answer in the second trial was distributed appropriatly. 3) Average mark of final test was 78.8 points, rather a higher rate of achievement than expected. This means that the program was constructed well.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.22 no.2
• /
• pp.225-238
• /
• 2012

Among the various security threats in online games, the use of game bots is the most serious problem. In this paper, we propose a framework for user behavior analysis for bot detection in online games. Specifically, we focus on party play that reflects the social activities of gamers: In a Massively Multi-user Online Role Playing Game (MMORPG), party play log includes a distinguished information that can classify game users under normal-user and abnormal-user. That is because the bot users' main activities target on the acquisition of cyber assets. Through a statistical analysis of user behaviors in game activity logs, we establish the threshold levels of the activities that allow us to identify game bots. Also, we build a knowledge base of detection rules based on this statistical analysis. We apply these rule reasoner to the sixth most popular online game in the world. As a result, we can detect game bot users with a high accuracy rate of 95.92%.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.15 no.6
• /
• pp.8-22
• /
• 1978

Recently developed Computed Topography (CT) reconstruction algorithms are reviewed in a more generalized sense and a few reconstruction examples are given for illustration. The construction of an image function from the physically measured projections of some object is Discussed with reference to the least squares optimum filters, originally derived to enhance the signal-to-noise ratio in communications theory. The computerifed image processing associated with topography is generalized so as to include 3 distinct parts: the construction of an image from the projection, the restoration of a blurred, noisy image, degraded by a known space-invariant impulse response, and the further enhancement of the image, e.g. by edge sharpening. In conjunction with given versions of the popular convolution algorithm, n6t 19 be confused with filtering by a 2-diminsional convolution, we consider the conditions under which a concurrent construction, restoration, and enhancement are possible. Extensive bibliographical limits are given in the references.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.76-76
• /
• 2013

Scanning Tunneling Microscopy는 개인용컴퓨터가 보급되고, 저잡음 아날로그 칩들을 구할 수 있으며, 압전세라믹 기술이 발달하기 시작한 1981년 스위스 IBM Zurich 연구소에서 H. Rohrer와 G. Binnig 박사에 의하여 발명되었다. 이 발명 7~8년 이전 미국 표준연구원의 R. Young 박사도 비슷한 시도를 하였지만, 이 때는 제어할 수 있는 컴퓨터가 없었고, 조절 회로의 잡음 레벨도 컸으며, 역학적 진동도 커서 목적을 달성할 수 없었다. STM의 발명 후 32년이 지난 지금, 조절용 컴퓨터의 발전은 물론, 조절용 역되먹임 회로 또한 digital signal processor나 FPGA를 사용하는 형태로 변화하여 전기적 잡음도 현저히 감소하였다 [1,2]. 동시에 측정 에너지 해상도를 개선하기 위하여 세계적으로 여러 그룹이 장치를 1 K 이하에서 작동할 수 있게 제작하였고, 0.3 K에서 작동하는 상업용 제품도 등장하였다. 이 결과 에너지 해상도는 30 meV 에서 2~3 ${\mu}eV$ 감소하였고, 온도변화에 따른 측정 위치의 변화도 피할 수 있게 되었다. 터널링 검침의 화학적 성분을 흡착과 같은 방법으로 조절하여, 공간 해상도는 물론 에너지 해상도도 더욱 줄일 수 있게 되었고, 스핀에 민감한 터널링 제어도 가능하게 되었다. 이제는 금속, 반도체, 초전도체는 물론 분자, 거대분자, 나노 크기의 양자점등도 측정이 가능하게 되었다. 분자진동 측정이 가능하며, 분자의 성분 분석이 가능하게 되었고, 스핀의 전도와 관련된 제반 문제들을 연구할 수 있게 되었다. 지금부터 10년 동안에는 포논의 측정과 전자와 포논 exciton 등이 관여된 다체계 현상, 이들의 동역학적 현상이 측정 가능하게 되었다. 핵자기 공명도 시도되고 있으며 화학적 구명 및 원자들 사이의 결합도 측정 가능하게 될 것이다. 이제 STM은 초고 진공에서 작동하는 Atomic Force Microscopy와 함께 지금까지 고체물리학 실험 장치가 만들어 내지 못하던 새로운 결과를 도출해 낼 것으로 기대한다.

• Journal of Engineering Education Research
• /
• v.15 no.3
• /
• pp.3-11
• /
• 2012

This paper discusses the effect that classroom demonstrations have on students' conceptual understanding in concepts in introductory physics. We used the same conceptual survey to probe the students' understanding on certain concepts before and after taking the course. We introduce Hake's , which is used to evaluate the effect of various kind of teaching methods, suggested by physics education research groups, on conceptual understanding of students who took the class. The effect of physics class using demonstration turned to be better than the traditional lecture, higher for students who graduated from science schools with higher prior knowledge and demonstration experience. Authors suggest to use to probe concepts which need more attention.

• Journal of the Korean Magnetics Society
• /
• v.6 no.5
• /
• pp.340-352
• /
• 1996

최근 급속도로 발전하고 있는 첨단산업의 배경에는 반도체를 중심으로 한 디지틀 전자기술(Electronics)이 자리잡고 있음은 주지의 사실이다. 이러한 전자 및 정보기술 이후, 즉 포스트 일렉트로닉스(Post-electronics)시대를 겨냥한 새로운 돌파구로서 기대되고 있는 21세기 기술의 주도권을 잡을 기술이 어떤 기술이 될 것인가는 매우 흥미로운 질문이다. 현재 시점에서 볼 때 반도체를 매개로 한 20세기 정보전자혁명을 대신할 새로운 기술혁명으로 대두하고 있는것이 마이크로혁명이며, 이 마이크로혁명을 주도할 기술로서 세계적인 주목을 끌고 있는 기술중의 하나가 초소형 미소기계, 즉 마이크로머신(Micromachine)이다. 현재 '반도체를 능가할 수 있는 차세대 메카트로닉스(Mechatronics)혁명'이라 평가되고 있는 마이크로머신 기술은 과거 꿈으로나 가능하던 공상과학의 세계를 현실로 만들어 주는 경이로운 기술이며, 나아가 분자기술을 응용한 생체로봇, 생체컴퓨터 등 이른바 나노기술(Nano-technology)의 신세계로 향하는 입구라 할 수 있다. 이기술은 기계공학, 전자기술은 물론 물리학, 생물학, 화학, 재료공학 등 광범위한 분야의 기술이 총망라되어야 개발이 가능하며, 그 실현을 위해서는 매크로 한 세계와는 판이하게 다른 물리현상 등 마이크로한 세계의 특수성을 이해해야 함은 물론 에너지공급, 재료, 데이타통신, 구조조립 등 많은 기술적 난제를 극복해야 한다. 마이크로머신기술은 현재 일부 전문가를 제외하고는 일반은 물론 자기학분야의 연구자들에게도 별로 익숙하지 않은 분야이다. 그러나 이 기술의 미래 영향력이나 가능성, 필요성을 고려할 때 이제는 자기분야 연구자들도 이 분야에 관심을 가져야 할 것으로 생각하여 연구자들도 이 분야에 관심을 가져햐 할 것으로 생각하여 본고에서는 먼저 최근 마이크로머신의 기술동향을 개괄적으로 소개하고, 다음으로 마이크로머신에 사용되는 주요 재료들과 자성재료가 주도적인 기능을 하는 자기마이크로머신(Magnetic Micro-machine)에 사용되는 자성재료들에 관해 소개하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.04a
• /
• pp.160-163
• /
• 2015

워크플로우 매니지먼트시스템은 오늘날의 어플리케이션들의 처리를 위한 효율적인 워크플로우 설계와 수행을 가능하게 한다. 그러나 전체물리학, 생물학, 지질학과 같이 과학탐구에 목적을 둔 어플리케이션들의 경우 대용량의 데이터를 연산해야 하기 때문에 단일 컴퓨팅 자원으로는 단 시간내에 작업을 완료하기 어렵다. 클라우드 환경에서 워크플로우를 효율적으로 수행하기 위해서는 여러 자원을 효율적으로 활용하기 위한 분산 병렬처리가 필수적이다. 일반적으로 시스템의 마스터노드에서는 클러스터의 원격노드들에게 어플리케이션 수행을 위해 설계된 워크플로우에 맞게 작업들을 분배하게 되는데 이때 마스터노드와 원격노드의 큐에서의 대기시간과 원격노드에서 할당된 작업들을 위한 스케줄링 시간은 성능을 좋지 않게 만드는 원인이 된다. 따라서 본 논문은 클라우드 환경에서 원격노드에서 작업수행이전까지의 지연시간을 줄이기 위한 최적화 방법으로 컴퓨팅 자원 활용도를 고려한 작업들의 병합 기법을 적용해서 워크플로우의 처리 속도를 향상시킨다.