• 한국생산제조학회지
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• 제18권5호
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• pp.514-520
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• 2009

Titanium is one of the most attractive materials due to their superior properties of high specific strength and excellent corrosion resistance. The applications in aerospace and medical industries demand machining process more frequently to obtain more precise products. Machining of titanium is faced with strong challenges such as increased component complexity i.e. airframe components manufacturing processes. The machining cost on titanium have traditionally demanded high cutting tool consumable cost and slow machining cycle times. Similarly, the high wear of the cutting tools restricts the cutting process capabilities. Titanium screws applied to fasten parts In the several corrosion environment. In the thread cutting of titanium alloys, the key point for successful work is to select proper cutting methods and tool materials. This study suggests a guidance fur selecting the cutting methods and the tool materials to improve thread quality and productivity. Some experiments investigate surface roughnesses, cutting forces and tool wear with change of various cutting parameters including tool materials, cutting methods, cutting speed. As the results, the P10 type insert tip was assured of the best for thread cutting of Ti-6Al-4V titanium alloy. Also the initial depth of infeed was desirable to use the value below 0.5mm as the uniform cutting area method is applied.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.38-44
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• 2008

Titanium and its alloys, due to their superior properties of high specific strength and excellent corrosion resistance, are increasingly used in living applications in the 21century. The applications in aerospace and medical industries demand machining process more frequently to obtain a desired product. But unfortunately, this material is one of the most difficult-to-cut. In the turning process of titanium alloys, the key point for successful work is to select proper tool materials and cutting conditions. This study suggests a guidance for selecting the tool materials and the cutting speeds to improve tool life and surface integrity in Ti-6Al-4V titanium turning process. The experiments investigate the change of surface roughnesses, cutting forces and flank wear with various cutting parameters of tool materials, depth of cuts and feeds. As the results, K10 type of insert tip was assured as the best for turning of Ti-6Al-4V titanium alloy.

• 컴퓨터교육학회논문지
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• 제9권2호
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• pp.69-78
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• 2006

교육평가란 학습자들을 서열별로 등급화 하는 과정이 아니라 적절한 평가를 통해 학습자의 문제를 해결하고 교육 과정을 개선하여 교육적 효과를 높이는 과정이다. 기존의 웹 기반 평가 시스템은 학습자의 인지 수준을 정 오답 이분 변수로만 측정하였다. 또한 수준별 평가를 지원하나 평가 시 학습동기 부여와 흥미를 이끌어 내는데 미흡하였으며, 평가 후 틀린 문제에 대한 피드백만을 제공하여 추후 학습 방향 설정과 재학습이 효율적으로 이루어지지 못한 문제점이 있다. 본 논문에서는 문제의 답지에 따라 학습자의 인지 능력을 좀 더 세밀하게 추정하고자 부분점수를 고려하여 문제를 출제하고 학습자의 수준을 평가하였으며 평가가 끝나면 학습 진단을 제공하여 피드백 학습이 효과적으로 이루어질 수 있도록 하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.757-765
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• 2002

This paper analyzes three theories for land degradation assessment and internationl/domestic methods for land degradation monitoring and assessment. Under the guidance of absolute degradation thought, this paper proposes the technological framework for monitoring and appraising cultivated land degradation based on the 3S technique. We can apply 3S technique and analyze the nature, the environmental, the social, and the economic elements which influence the land utilization and degradation synthetically, to set up the indicator system of the cultivated land degradation monitoring and assessment based on 3S technique; to propose the degradation information extraction methods based on 3S technique; to create the quantitative assessment model and method for land degradation; to analyze the ecological environment response of land use and degradation quantitatively; and to propose the measure, policy and suggestion for solving the land degradation problem from the point of view of land utilization.

• 비교문화연구
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• 제26권
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• pp.43-71
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• 2012

In this article, we recognize the cross-cultural communication between Greece and Spain through El Greco's pictures. The Greeks of Crete kept to their culture and continued to look to the declining Byzantine Empire for spiritual and political guidance. For two centuries after the conquest, the strength of the Byzantine tradition had become the moral and spiritual sustenance of the conquered in Crete. The basic contribution of Cretan intellectuals or artists such as El Greco of the fifteenth and sixteenth centuries was the forging of connecting links between the Hellenism of the old Byzantine East and the rising, youthful Hellenism of the Renaissance West. In this way, Crete served as an important halfway point between East and West. The saint Mary Magdalene was symbol of Christian penitence, which represents the penitential life personified and became widespread during the Counter Reformation, when new emphasis was put on the value of prayer and repentance in the forgiveness of sin. In Spain, the Penitent Magdalene was popular and El Greco painted many versions, which at the first time, were reflected by Tiziano, on the contrary, at the time of Toledo, were recreated by his own style. Although El Greco was converted to Catholic in Spain, his faith in Greek Orthodox Church influenced on his original painting world. El Greco had never painted a picture whose subject treat with the emphasis of identification between Mary Magdalene and Mary, younger sister of Martha.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1975-1988
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• 2019

Short-term traffic flow prediction plays an important role in intelligent transportation systems (ITS) in areas such as transportation management, traffic control and guidance. For short-term traffic flow regression predictions, the main challenge stems from the non-stationary property of traffic flow data. In this paper, we design an ensemble cascading prediction framework based on extremely randomized trees (extra-trees) using a boosting technique called EET to predict the short-term traffic flow under non-stationary environments. Extra-trees is a tree-based ensemble method. It essentially consists of strongly randomizing both the attribute and cut-point choices while splitting a tree node. This mechanism reduces the variance of the model and is, therefore, more suitable for traffic flow regression prediction in non-stationary environments. Moreover, the extra-trees algorithm uses boosting ensemble technique averaging to improve the predictive accuracy and control overfitting. To the best of our knowledge, this is the first time that extra-trees have been used as fundamental building blocks in boosting committee machines. The proposed approach involves predicting 5 min in advance using real-time traffic flow data in the context of inherently considering temporal and spatial correlations. Experiments demonstrate that the proposed method achieves higher accuracy and lower variance and computational complexity when compared to the existing methods.

• 헤리티지:역사와 과학
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• 제36권
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• pp.39-67
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• 2003

In this paper we examine cultural properties of the North Korea from 'the law of the Democratic People's Republic of Korea on Protection of Cultural Property". This law was adopted the Resolution of the Standing Committee of the Supreme People's Assembly of DPR of Korea in 1994. For our study, some other laws or rules established after the end of Japanese colonial occupation (1910-1945) in North Korea were examined. The policy on protection and conservation of cultural property in North Korea seems to have taken place a relatively rapid. The purpose of this law is to carry out the policy with a view to contributing to establishment of strict system and order for protection and management of cultural property, to their preservation in original state, to their proper inheritance and development, and to enhancement of national pride and confidence among the people. This law consists of 6 chapters (52 articles): (1) Fundamentals of the law on protection of cultural property, (2) Archaeological excavation and collection of cultural relics, (3) Evaluation and registration of cultural property, (4) Preservation and management of cultural property, (5) Restoration of cultural property, and (6) Guidance and control of cultural property protection. Nevertheless, it is difficult to find the evidence of efforts to exploit the cultural properties from an academic point of view in North Korea since the late 1980s.

• 해양환경안전학회지
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• 제25권3호
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• pp.287-297
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• 2019

The recent increase in crude oil trading has led to an increase in the workings of SPM for crude oil carriers. VLCCs generally encounter difficulty entering port due to limitations in terms of sea depth and maneuverability. The SPM is a system that allows mooring to the buoy located in the outer sea for such vessels. However, the buoy is more affected by relatively external forces because of their of shore location. Therefore, the safety assessment of SPM is particularly important as it can lead to large oil pollution disasters in the event of SPM accidents. Despite this, in the implementation of the Marine Traffic Safety Audit Scheme in Korea, there exists no guidance for SPM. In this study, a SPM mooring safety assessment is performed using OPTIMOOR, a numerical analysis program, so as to understand the mooring characteristics of SPM. As a result, it is confirmed that the tension of mooring lines and hull movement in the SPM are greatly affected by the encounter angles with external forces. In addition, it is found that the maximum tension of the mooring line is elevated as the water depth becomes shallower through sensitivity analysis. According to SPM characteristics, which has a large influence on the encounter angle, this study has proposed an amendment to setting criteria in the implementation of the Maritime Traffic Safety Audit Scheme which could improve the reliability and accuracy of mooring safety assessments.

• 대한치과보철학회지
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• 제60권4호
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• pp.301-312
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• 2022

광범위한 전악 보철 수복 시 적절한 교합 수직 고경(occlusal vertical dimension)의 설정은 성공적인 치료를 위해 매우 중요한 단계이자 치료의 시작점이 된다. 수직 고경의 변경을 통한 술식은 치료가 침습적일 수 있으며, 환자 및 임상의들의 많은 시간과 비용, 노력을 필요로 하기 때문에, 진단 및 치료 진행 과정에 다각적인 분석과 심도 깊은 고찰이 필수적이다. 본 논문에서는 선행 문헌들의 검토를 통해 수직 고경의 개념과 관련된 여러 쟁점들에 대해 정리하고, 다양한 수직 고경 평가법들을 정리하여 전악 구강 회복 치료 시 적절한 수직 고경을 설정하기 위한 임상적 방법과 이에 대한 근거를 제시하고자 한다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.258-259
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• 2021

휴양림은 산림자원과 부대시설 그리고 이용객으로 구분되며, 웰빙 문화와 더불어 끊임없이 이용되고 있다. 이와 함께 이용객의 안전에 대한 관심이 필요하며, 본 연구에서는 산림에서 발생할 가능성이 있는 자연재해 상황에서 이용객이 빠른 시간(golden time)내에 대피하는 방법에 대해 연구하고자 한다. 이용객의 현재 위치를 탐색하고 최적을 대피로를 찾기 위해 휴양림 전체(산림자원, 부대시설 등)를 3D 스캔을 실시하고, 현 위치 인식으로 통해 대피 장소까지의 최적을 궤적을 찾아 이용객이 소지하고 있는 모바일 장치를 통해 빠른 대피 안내를 하는 것이 가능할 것으로 생각된다.