• 정보처리학회논문지C
• /
• 제11C권6호
• /
• pp.773-780
• /
• 2004

본 논문에서는 대표적인 스트림형 트래픽인 DV와 MPEG2를 초고속 네트워크 상에서 전송하고 이들 스트림에 대한 최종 사용자의 주관적 평가를 수행하였다. 두 가지 스트림형 데이터에 대해 화질 측정은 ITU-R BT.500-1을 기반으로 하여 측정하였고, 음질 측정은 ITU-R BS.1116-1을 기반으로 측정하였다. 또한 최종 사용자의 주관적 평가를 얻기 위한 실험 방법으로는 DSCQS 5단계 평가 방법을 채택하였다. 유사한 조건하에서 MPEG2 스트림의 경우, 네트워크 트래픽 파라미터가 급증하는 $54\%$의 부하율에서 화질과 음질의 평가 등급이 급격히 하강한다. DV의 경우 화질은 MPEG2와 마찬가지로 $54\%$의 부하율에서 평가 등급이 하락하지만 그 변화의 정도가 MPEG2에 비해 완만하며 점진적인 것을 확인할 수 있다. 반면 DV 음질의 경우는 부하율 $70\%$까지 사용자의 주관적 평가 등급이 우수하여 사용자의 주관적 평가를 고려한 트래픽 제어 및 QoS 제어가 요구된다. 결론적으로 MPEG2의 경우는 네트워크 상의 실측값과 최종 사용자의 주관적 평가가 거의 동일하므로, 네트워크 실측값만으로 트래픽 제어가 가능하고, DV의 경우는 네트워크 상의 실측값과 최종 사용자의 주관적 평가 등급을 동시에 고려한 트래픽 제어가 가능하다.

• Journal of information and communication convergence engineering
• /
• 제12권1호
• /
• pp.26-32
• /
• 2014

Vehicular-to-anything (V2X) technology is attractive for wireless vehicular ad-hoc networks (VANETs) because it allows for opportunistic choice of a vehicular protocol between vehicular-to-vehicular (V2V) and vehicular-to-infrastructure (V2I) communications. In particular, achieving seamless connectivity in a VANET with nearby network infrastructure is challenging. In this paper, we propose a density-based opportunistic broadcasting (DOB) protocol, in which opportunistic connectivity is carried out by using the nearby infrastructure and opposite vehicles for solving the problems of disconnection and long end-to-end delay times. The performance evaluation results indicate that the proposed DOB protocol outperforms the considered comparative conventional schemes, i.e., the shortest path protocol and standard mobile WiMAX, in terms of the average end-to-end delay, packet delivery ratio, handover latency, and number of lost packets.

• Steel and Composite Structures
• /
• 제29권3호
• /
• pp.391-404
• /
• 2018

Researchers have been long studying new building implementation methods to improve the quality of construction, reduce the time of assembly, and increase productivity. One of these methods is the use of modular pre-fabricated structural forms that are composed of a beam, column, short column, pyramidal end block, and connection plates. In this study, a new geometry for the pyramidal end block was proposed that helps facilitate the assembly procedure. Since the proposed configuration affects the performance of this form of connection, its behavior was evaluated using finite element method. For this purpose, the connection was modeled in ABAQUS and then validated by comparing the outputs with experimental results. The research proceeded through analyzing 16 specimens under monotonic and cyclic loading. The results indicated that using the pyramidal end block not only makes the assembly process easier but also reduces the out-of-plane displacement of the short column webs and the vertical displacement of beam end. By choosing appropriate section properties for column and beam, the connection can bear a rotation up to 0.01 radians within its inelastic region and a total of 0.04 radians without any significant reduction in its bearing capacity.

• 한국기계가공학회지
• /
• 제16권4호
• /
• pp.135-139
• /
• 2017

In recent years, the optical fiber laser has been widely used in industrial fields due to its excellent economical efficiency and its suitability for industrial applications. This usage has increased even further since the KW class Laser was developed. In this paper, structural analysis and heat transfer analysis of a 500W class optical fiber laser end cap module was performed. The stability of end cap housing with the efficient heat dissipation structure of a 500W-class end cap was evaluated. This research determined the optimal design that should be applied to the design and evaluation of future KW class laser output modules.

• Clinics in Shoulder and Elbow
• /
• 제2권1호
• /
• pp.35-40
• /
• 1999

Impingement syndrome is caused by a conflictual status between rotator cuff, subacromial bursa and anatomic and functional coracoacromial arch. The purpose of this study was to assessment the coracoacromial arch by MRI and to determine major factors among five components of coracoacromial arch. We analyzed forty-two cases of clinical impingement sign and test positive and postoperative confirmed diagnosed from March, 1991 to January, 1999. We evaluated acromial end abnormality according to the Bigliani acromial type and formation of osteophyte. Clavicular end abnormality classified flat, outward protrusion, inward protrusion to coracoacromial arch. Acromioclavicular joint abnormalities were advanced osteoarthritis and positive signal change. Coracoacromial ligament thickening was above 2 mm in oblique sagittal image. Coracoid process abnormality was inward protrusion to coracoacromial arch. All consecutive patients abnormalities were as follows: clavicular end osteophyte formation and inward protrusion to coracoacrmial arch were 30%, acromial end osteophyte formation was 28%, advanced acromioclavicular joint arthritis and osteophyte formation were 56%, coracoacromial ligament thickening was 24% and no coracoid process inward protrusion to coracoacromial arch. Impingement syndrome combined with rotator cuff tear group abnormalities were clavicular end(40%), acromial end(40%), acromioclavicular joint(20%), coracoacromialligament(20%) and coracoid process abnormality(0%) respectively. Only impingement syndrome group abnormalities were clavicular end(25%), acromial end(31%), acromioclavicular joint(62%), coracoacromial ligament(25%) and coracoid process(0%) respectively. Acromial type I(flat) were 6 cases, type II(curved) were 26 cases and type III(hooked) were 10 cases. We concluded that the most important contributing factors for impingement syndrome was acromial type and second was acromioclavicular joint arthritis and bony spur formation.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 C
• /
• pp.1150-1152
• /
• 1998

Recently, our electric industry confronts a structural change and high competiveness environment in the course of deregulation. Rapid growth in electricity demand, financial need for new power plant construction, and envionmental problems have led to search for more efficient energy production and energy conservation techmologies. Especially, residential and commercial buildings consumes 40% of electricity demands and building energies are increasing more and more in Korea. The purpose of this paper is to analyze the electricity use of commercial buildings by end-use. Also, we will use it as a basic informations of DSM potential evaluation and evaluation process based on different approach by sector and type of potential.

• Clinics in Shoulder and Elbow
• /
• 제6권2호
• /
• pp.131-137
• /
• 2003

Purpose: Unstable Neer type II lateral end fracture of clavicle may be required operation. The purpose of this study is the effectiveness of the use of Hook plate in the management of unstable Neer type II fractures. We preliminary reported the results of Unstable Neer type II lateral end fracture of clavicle using by Hook plate. Material and Methods: From May 1998 to May 2002, we operated 6 cases unstable Neer type II lateral end fracture of clavicle with Hook plate by one surgeon. We checked radiologic evaluation and disappearance of pain per 1 week, and evaluated improvement of range of motion per 2 week. And we followed up at each interval 3 months,6 months, 12 months and after that per 6months interval, at that each time we checked stress radiogram of shoulder and functional evaluation. The shoulder function was evaluated using Modified Shoulder Rating Scale (MSRC) for Distal Clavicle Fracture and UCLA score. Average follow up was on 37.2 (12∼57) months. Results: All 6 patients were regained satisfactory function. Average MSRC for distal clavicle fracture was 17.3 (15∼20) and average UCLA score was 33.2 (31∼35) at last follow up. Conclusion: There are many advantage of the use of Hook plate on management of unstable Neer II distal clavicle fracture in spite of several disadvantage. There have not yet been reported in our country. So we obtained good to excellent clinical result in surgical treatment of 6 cases on type II displaced lateral end fracture of the clavicle. But we think that more cases will be review and longer follow up will be needed in the future.

• International Journal of Advanced Culture Technology
• /
• 제6권4호
• /
• pp.131-142
• /
• 2018

This research examines the impact of teachers' self-evaluation on their classroom interactions with students. Changes in class behavior were analyzed by following two experienced middle school teachers for one semester of self-evaluation, comparing their classes at the beginning and end of the semester. A qualitative research method was adopted to take, a deeper look at the effect of changes in the teachers' in class actions. Both of the teachers reported positive effects of implementing self-evaluation on their teaching pedagogy, focusing specifically on their interactions with students when asking question and giving feedback. By the end of semester, they were asking broader questions that encouraged their students to engage in deeper thought and, when giving feedback, the class atmosphere was much brighter with better communication due to the positive reinforcement provided. This research supports research into ways to enhance teachers' expertise and improve their teaching via self-evaluation, centering on teachers' actions in the classroom.

• 로봇학회논문지
• /
• 제15권2호
• /
• pp.91-99
• /
• 2020

Fruit and vegetable harvesting robots have been widely studied and developed in recent years to reduce the cost of harvesting tasks such as labor and time. However, harvesting robots have many challenges due to the difficulty and uncertainty of task. In this paper, we characterize the crop environment related to the harvesting robot and analyzes state-of-the-art of the harvesting robot especially, in the viewpoint of robotic end-effector. The end-effector, an one of most important element of the harvesting robot, was classified into gripper and harvesting module, which were reviewed in more detail. Performance measures for the evaluation of harvesting robot such as test, detachment success, harvest success, and cycle time were also introduced. Furthermore, we discuss the current limitations of the harvesting robot and challenges and directions for future research.

• 정보관리학회지
• /
• 제20권1호
• /
• pp.75-91
• /
• 2003

본 연구는 정보기술의 발전과 사용자 중심의 개발환경으로 인해 변화된 정보환경 속에서 정보센터의 새로운 방향 설정을 위해 정보센터의 관리 특성요인과 사용자의 만족도를 중심으로 그 상관관계를 살펴보았다. 본 연구가설의 검증을 위해 서로 다른 정보센터를 활용하고 있는 41명의 사용자로부터 설문을 받아 활용하였다. 조직의 정보서비스에 대한 사용자의 만족도 향상에 유의한 영향을 미치는 것으로 파악된 정보센터와 관련된 활동들을 살펴봄으로써 최근의 사용자 중심의 정보환경 속에서 새롭게 고려되어야 할 사항들에 대해 논의하였다. 본 연구결과는 시스템측면에서 새롭게 변한 정보센터가 사용자들에 대한 서비스활동의 강화를 위해 고려해야 할 사항에 대한 식견을 제공할 것으로 사료되어진다.