• Structural Monitoring and Maintenance
• /
• v.3 no.4
• /
• pp.395-406
• /
• 2016

Modal parameter identification has received much attention recently for their usefulness in earthquake engineering, damage detection and structural health monitoring. The identification method based on Matrix Pencil technique is adopted in this paper to identify structural modal parameters, such as natural frequencies, damping ratios and modal shapes using impulse vibration responses. This method can also be applied to dynamic responses induced by stationary and white-noise inputs since the auto- and cross-correlation function of the two outputs has the same form as the impulse response dynamic functions. Matrix Pencil method is very robust to noise contained in the measurement data. It has a lower variance of estimates of the parameters of interest than the Polynomial Method, and is also computationally more efficient. The numerical simulation results show that this technique can identify modal parameters accurately even if the noise level is high.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.10a
• /
• pp.117-120
• /
• 2003

Joining or welding of dissimilar metallic materials is very difficult problem because material properties like heat conductivity, melting points, coefficient of thermal expansion, etc. are different each other and cracks are occurred easily due to formation of intermetallic compounds. Nevertheless, deep attention from great industrial demands and trials to joining dissimilar materials has been increased steadily. In this study, TIG welding of Cu to Al is tried and tensile test, SEM and EDX analysis are carried out.

• The Journal of Advanced Prosthodontics
• /
• v.2 no.3
• /
• pp.88-91
• /
• 2010

Mandible fractures belong to the most common fractures encountered in maxillofacial trauma. Because mandible is such a unique structure with hinge joint and masticatory muscles attached to the body of mandible, attention must be paid to avoid displacement during treatment. Displacement during fracture reduction leads to malocclusion. Many TMJs function with complete comfort and apparent normalcy in adapted centric posture, even though they have undergone deformation caused by trauma. This clinical report describes the patient with post traumatic malocclusion and its prosthetic treatment. His fractured mandible was openly reduced in changed position, as a result his occlusion has been changed. He was treated by prosthetic method in so-called adapted centric posture.

• Journal of Computing Science and Engineering
• /
• v.6 no.4
• /
• pp.243-256
• /
• 2012

In this paper we present a framework for a novel kind of context-aware preference query composition whereby queries for the Preference SQL system are created. We choose a commercial e-business platform for outdoor activities as a use case and develop a context model for this domain within our framework. The suggested model considers explicit user input, domain-specific knowledge, contextual knowledge and location-based sensor data in a comprehensive approach. Aside from the theoretical background of preferences, the optimization of preference queries and our novel generator based model we give special attention to the aspects of the implementation and the practical experiences. We provide a sketch of the implementation and summarize our user studies which have been done in a joint project with an industrial partner.

• Annual Conference on Human and Language Technology
• /
• 2018.10a
• /
• pp.252-255
• /
• 2018

화행 분석이란 자연어 발화를 통해 나타나는 화자의 의도를 파악하는 것을 말하며, 슬롯 필링이란 자연어 발화에서 도메인에 맞는 정보를 추출하기 위해 미리 정의되어진 슬롯에 대한 값을 찾는 것을 말한다. 최근 화행 분석과 슬롯 필링 연구는 딥 러닝 기반의 공동 학습을 이용하는 연구가 많이 이루어지고 있고 본 논문에서는 한국어 특허상담 도메인 대화 말뭉치를 이용하여 공동 학습 모델을 구축하고 개별적인 모델과 성능을 비교한다. 또한 추가적으로 공동 학습 모델에 주의집중 메커니즘을 적용하여 성능이 향상됨을 보인다. 최종적으로 주의집중 메커니즘 기반의 공동 학습 모델이 기준 모델과 비교하여 화행 분류와 슬롯 필링 성능이 각각 3.35%p, 0.54%p 향상되어 85.41%, 80.94%의 성능을 얻었다.

• Proceedings of the KWS Conference
• /
• 2006.10a
• /
• pp.292-294
• /
• 2006

Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the butt welding has been paid much attention to joint PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after developing the heat plate of new shape, the PE double wall pipes with misalignments were butt-welded by using the conventional and developed heat plates and comparison of weld-zones and tensile test was performed. As the results of tensile test, weld-zones using developed heat plate have strength of $147.7{\sim}251.0%$ of weld-zones using conventional heat plate.

• Journal of computational fluids engineering
• /
• v.6 no.3
• /
• pp.27-31
• /
• 2001

For rapid and abrupt control of a missile in supersonic flight, side jet on a missile body is found to be a useful device as evidenced by recent missile development at several nations. The magnitude of the side jet and the duration of it decide the level of control of such a missile system. In this paper, the aerodynamic characteristics of the side jet device itself are examined in terms of key parameters such as the side jet nozzle geometry, the chamber pressure and temperature. Specifically attention is paid to the effect of the chamber shape between the straight nozzle and the bent nozzle by 90 degrees on the nozzle flow properties. The thrust magnitudes are compared between the two shapes. Whether the way the nozzle is bent at the joint affects the nozzle performance is also investigated. Effects of the length and the divergence angle of the nozzle on the thrust are also quantified among three different side jet nozzles.

• Research in Mathematical Education
• /
• v.14 no.1
• /
• pp.11-18
• /
• 2010

The basic idea of cooperative learning focuses on team reward, equal opportunities for success, cooperation within team and competition among teams, and emphasizes share of sense of achievement through joint efforts so as to realize specific learning objectives. The main strategies of engineering mathematics teaching based on cooperative learning are to establish favorable team and design reasonable team activity plan. During the period of team establishment, attention shall be given to team structure including such elements as team status, role, norm and authority. Team activity plan includes team activity series and team activity task. Team activity task shall be designed to be a chain of questions following a certain principle.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.323-327
• /
• 2001

Electrorheological(ER) and magnetorheological(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. Controllable fluids such as ER and MR fluids have received considerable attention as several components of engineering devices. One of them is a smart impact damper using ER/MR fluids. Impact damper system can be used in the joint mechanism of railroad vehicle, protection equipment of elevator's drop, and launch equipment of aircraft. This paper presents the results of an analytical study of the performance of a smart impact damper to suppress vibration during impact excitation. The damping capabilities of MR impact damper for variable applied current are analyzed using Bingham model under sudden impact load.

• Journal of Welding and Joining
• /
• v.34 no.2
• /
• pp.30-35
• /
• 2016

Last few decades have seen a rapid increase in the fabrication and characterization of Al alloys for automobiles, heat exchangers and aerospace industries. Aluminium alloys are popular because of their high specific strength, light weight, excellent wear and high oxidation resistance. The development of aluminium alloys in these applications makes their study and research of utmost importance. Brazing is applied to the aluminium alloys for joining various aluminium parts together in most of the industrial applications. Various parameters affect the joining process of these aluminium alloys. In this article, various types of processing parameters have been discussed, and special attention has been given to the category of aluminium brazing alloys. The article reviews on the various parameters that affect the brazing property in various scientific and technological applications.