• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.3
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• pp.305-312
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• 2012

This paper aims at improving the accuracy and computational efficiency in reconstructing building boundaries from airborne Lidar points. We proposed an adaptive convex hull algorithm, which is a modified version of local convex hull algorithm in three ways. The candidate points for boundary are first selected to improve efficiency depending on their local density. Second, a searching-space is adjusted adaptively, based on raw data structure, to extract boundary points more robustly. Third, distance between two points and their IDs are utilized in detecting the seed points of inner boundary to distinguish between inner yards and inner holes due to errors or occlusions. The practicability of the approach were evaluated on two urban areas where various buildings exist. The proposed method showed less shape-dissimilarity(8.5%) and proved to be two times more efficient than the other method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.12
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• pp.79-90
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• 2000

In this paper, a high-performance floating point unit, which is suitable for high-performance superscalar microprocessors and supports IEEE 754 standard, is designed. Floating-point arithmetic unit (AU) supports all denormalized number processing through hardware, while eliminating the additional delay time due to the denormalized number processing by proposing the proposed gradual underflow prediction (GUP) scheme. Contrary to the existing fixed-radix implementations, floating-point divide/square root unit adopts a new architecture which determines variable length quotient bits per cycle. The new architecture is superior to the SRT implementations in terms of performance and design complexity. Moreover, sophisticated exception prediction scheme enables precise exception to be implemented with ease on various superscalar microprocessors, and removes the stall cycles in division. Designed floating-point AU and divide/square root unit are integrated with and instruction decoder, register file, memory model and multiplier to form a floating-point unit, and its function and performance is verified.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.7-13
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• 2016

As of many organochlorine pesticides, polychlorinated biphenyls are ubiquitous organic contaminants, which can be found in the most environmental matrices. Their toxic effects include endocrinedisrupting activity. Most researches with these toxicants performed with mixtures of congeners, namely Aroclor and related study has been done in complex environmental matrix, rather than single biosystems or pure congeners. 5 congeners were synthesized and their fates in pure microbial culture (Aspergillus niger) were determined in this study. Among biphenyl and synthetic congeners, biphenyl, PCB-1 (2-chlorobiphenyl), and PCB-3 (4-chlorobiphenyl) were rapidly transformed to hydrophilic metabolites, followed by PCB-38 (3,4,5-trichlorobiphenyl), while the degradation of PCB-126 (3,3',4,4',5-pentachlorobiphenyl) was not observed. The amounts of transformation for biphenyl, PCB-1, PCB-3, and PCB-38 were 65, 38, 52, and 2% respectively. The major metabolites of the above congeners were identified as mono- and di-hydroxy biphenyls, which are known to give adverse endocrinological effects.

• Journal of The Korean Association For Science Education
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• v.6 no.2
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• pp.63-72
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• 1986

과학교육은 학생들이 장차 과학 기술분야의 직업을 추구하도록 하는 것을 그 중요한 결실의 하나로 잡고 있다. 현재 한국은 과학과 기술의 발전을 교육의 주요목표의 하나로 삼고 있으며, 정부에서는 보다 많은 영재를 과학 기술분야로 유치하려고 여러 가지 정책을 펴고 있다. 그러나 이러한 정책도 결국은 학생이 과학 기술분야로 모여들지 않으면 그 효과가 없게 된다. 그런 점에서 학생들이 어떤 이유로 과학 기술분야를 선택하는지 혹은 기피하는지 그 원인을 아는 것을 중요한 과제라고 할 수 있다. 본 연구는 과학 및 기술분야의 직업을 갖게 되는데 결정적인 역할을 하는 고교생의 문 이과반 선택에 있어 그 진로결정에 영향을 주는 제 요인들을 규명하는데 목적을 두고있다. 연구대상은 대구시내외 남 녀 고교 1학년생 109명(문과 56명, 이과 53명)이었으며 조사방법은 설문지법을 사용하였다. 조사결과는 학생들의 문 이과반 선택에는 장래직업, 대학전공, 적성, 학과목에 대한 능력, 흥미 선호도, 가족 및 주위의 권유 등이 주요요인임을 보여주고 있다. 그중 문과를 지원한 학생들은 대체적으로 자신의 적성 이과과목에 대한 능력부족 인식, 내신 및 학력고사에서의 성적취득용이성 등 주로 자신의 내적 동기와 관련된 요인들을 들고 있는데 비해, 이과를 지원한 학생들은 밝은 직업전망, 가족 및 주위의 권유 등 외적인 동기도 큰 작용을 하고 있음을 보여 대조를 이루고 있다. 또 문과를 지원한 학생은 이과가 공부하기가 어렵고 성적을 올리기도 힘들어 이과를 기피한 경향을 보이는데 반해 이과 지원자는 문과를 기피하여 이과로 왔다는 응답은 별로 없는 점이 대조를 보였다. 본 논문은 이러한 결과가 던져주는 시사점과 과학교육의 개선책에 관한 제언을 제시하면서 결론을 맺고 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.690-692
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• 2013

Cloud computing is an Internet-based technology, one of the Big Data era aspiring technology. Bring on the internet whenever you need to use multiple physical servers into one virtual server, cloud Cloud technology and large companies, such as leading U.S. IT company, Amazon, IBM, Google, Microsoft and the domestic firm Samsung, SK, KT, NHN the cloud market at home and abroad, and commercialization by investing in the future to continue to grow. The main reason for the introduction of the cloud and reduced operating costs, and to see the most problems is the leakage of personal information. In this paper, we propose a method to improve the security and vulnerability analysis of security technologies and cloud.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.3 no.2
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• pp.1-10
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• 1985

Moire technique is generally divided into shadow Moire Technique and Projection Moire Technique. In this paper, determinating the direction of reference planes for this system, by comparing the results of this system with those of general terrestrial photogrammetry, is an objective of this paper. For the objective, control surveying is done and the results of control surveying are compared with those of moire photograph. In this technique, it is found that though the positions of a projector and a reference grid are not moved, a desired moire contour whose the reference plane is different respectively is easily obtained by changing the pitches of a master grid and a reference grid on an object. Also it is found that when the pitches of the two grids on an object are equal, a moire contour which has the reference plane parallel to the object can be obtained.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.243-250
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• 2007

The purpose of this study is to examine the relationship between internet addiction and stress of college students. To assess the degree of internet addiction, internet addiction test of the center for online addiction was completed. Subjects were divided into three group depending on internet addiction ; subjects with 20-49 internet scores were grouping as 'normal usage group', subjects with 50-79 internet scores were grouping as 'addiction tendency group', and subjects with more than 80 internet scores were grouping as 'internet addiction group'. In this study it is found that interpersonal relationship stress is significantly related to internet addiction. Also, the result of this study shows that home background stress and school background stress have influence on internet addiction.

• The Journal of Korean Association of Computer Education
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• v.15 no.6
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• pp.21-31
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• 2012

The purpose of this study was to examine acceptance factors that affect the intention to use digital textbook. The results are as follow. First, the quality characteristic factor has significant effects on the ease of use, the usefulness of use, and the intention of use. Second, the ease of use appeared to be a significant impact on the usefulness of the use. The usefulness of digital textbook appeared to be a significant impact on the intention of use. The results show that the quality characteristics consisted of six components: personalization, mobility, stability, accuracy, responsiveness, and accessibility. The results can suggest important implications for the development of digital textbook contents and system.

• Fire Science and Engineering
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• v.20 no.3 s.63
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• pp.29-34
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• 2006

The flash and fire point are the most important combustible properties used to determine the potential for the fire and explosion hazards of flammable material. The flash point is defined as the lowest temperature at which a flammable liquid gives off sufficient vapor to form an ignitable mixture with air near its surface or within a vessel. The fire point is the temperature of the flammable liquid at which there will be flaming combustion, sustained 5 seconds in response to the pilot flame. In this study, the flash points and fire points were measured to present raw data of the flammable risk assessment for acids, using Pensky-Martens Closed Cup(C.C.) apparatus (ASTM-D93) and Tag Open-cup (O.C.) apparatus(ASTM D 1310-86). The measured fire points were compared with the estimated values based on 1.11 times stoichiometric concentration. The values calculated by the proposed equation were in good agreement with measured values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.61-66
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• 2012

In this study, to find the effect of nonequilibrium condensation on the oscillation of the terminating shock wave in transonic flows, an NACA0014 airfoil flow with nonequilibrium condensation is analyzed using the total variation diminishing (TVD) numerical scheme. Transonic free stream Mach numbers of 0.81-0.87 are tested with variations in the stagnation relative humidity. For the same free stream Mach number and attack angle of ${\alpha}=0^{\circ}$, an increase in the stagnation relative humidity attenuates the strength of the terminating shock and reduces the oscillation of the terminating shock wave. Furthermore, for the same stagnation relative humidity, the larger the free stream Mach number becomes, the shorter the period of the oscillation shock wave is. The excursion distance of the oscillation shock increases with the free stream Mach numbers for the same stagnation relative humidity. Finally, it is found that for the same shock location, the strength of the oscillating shock facing upstream is stronger than that facing downstream.