• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1446-1449
• /
• 2008

Immune system is composed of multiple cells with distinct functions, and immune responses are orchestrated by complex and dynamic cell-cell interactions. Therefore, each cell behavior and function should be understood under right spatio-temporal context. Studying such complexity and dynamics has been challenging with conventional biological tools. Recent development of new technologies such as state of art imaging instruments and microfabrication techniques compatible with biological systems have provided many exciting opportunities to dissect complex and dynamic immune cell interactions; new microscopy techniques enable us to observe stunning dynamics of immune system in real time. Microfabrication permits us to manipulate microenvironments governing molecular/cellular dynamics of immune cells to study detailed mechanisms of phenomena observed by microscopy. Also, microfabrication can be used to engineer microenvironments optimal for specific imaging techniques. In this presentation, I am going to present an example of how these two techniques can be combined to tackle challenging problems in immunology. Obviously, this strategy can readily be applied to many different fields of biology other than immunology.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.631-636
• /
• 2008

The cylindrical shells are mainly used in the nuclear energy structure, pressure vessel, boiler and so on. When designing of shell structures, predicting the structure change under variety boundary conditions are necessary for estimating the safety. Design variables for the design engineer include multiple material systems and boundary conditions, in addition to overall structural design parameters. Since the vibration of stiffened cylindrical shell is an important consideration for structures design, the reliable prediction method and design methodology should be required. In this study, the optimum design of stiffened cylindrical shell for maximum natural frequency was studied by analytic and numerical method.

• Smart Structures and Systems
• /
• v.7 no.3
• /
• pp.223-228
• /
• 2011

An understanding of biomaterials' smart properties and how biocomposite materials are manufactured by cells provides not only bio-inspiration for new classes of smart actuators and sensors but also foundational technology for smart materials and their manufacture. In this case study, I examine the unique smart properties of bone, which are evident at multiple length scales and how they provide inspiration for novel classes of mechanoactive materials. I then review potential approaches to engineer and manufacture bioinspired smart materials that can be applied to solve currently intractable problems such as the need for "smart" body armor or decor cum personal safety devices.

• Korean Journal of Computational Design and Engineering
• /
• v.8 no.3
• /
• pp.184-188
• /
• 2003

The harness design process consists of repetitious routines to decide the wire configuration in its interior. A slight change in one of the wire's configuration will require a total reconfiguration of the entire wire system. Therefore, the harness design is extremely time consuming and is vulnerable to human errors by an engineer. Based on both electrical and mechanical area, Wiring Harness system is in complicated area. Existing systems are, therefore, not exactly suitable for practical use. This paper presents a novel framework for ameliorating existing system's defects. In this paper, Visio and Visual Basic was interfaced to process wire bundle information and wire bundle location to alleviate problems mentioned beforehand concerning harness design; at the same time developing the automation of the entire design process based on the feature based design method, optional print, and management of documents for reuse.

• Journal of the Korean Professional Engineers Association
• /
• v.44 no.1
• /
• pp.48-52
• /
• 2011

The KEPCO Research Institute has developed Molten Carbonate Fuel Cell(MCFC) since 1993. Recently, an 125-kW MCFC system was operated at Boryeong thermal power plant, Korea from December, 2009 to March, 2010, This system is composed of an 125-kW stack, mechanical balance of plant (MBOP), and Power Conditioning System. The stack has 200 unit cells of which effective area is 10,000 cm2. Especially, MBOP is mainly made up of ejector and catalytic combustor which help this system to be supplied with cathode inlet gas using anode tail gas and fresh air. After the pretreatment of this system was performed for about 20 days, initial load operation was performed at January. 2010. Moreover, this system had been operated for 3,270 hours.

• Journal of Korea Foundry Society
• /
• v.12 no.1
• /
• pp.62-73
• /
• 1992

상변환시 수반되는 경계면에서의 잠열의 방출(또는 흡수)의 정확한 해석은 용접, 주조, 결정 생성, 일기 예보 등의 응용에 필수적인 것이다. 특히 주조의 경우 캐스팅 온도와 고체 용적분율의 관계를 앎으로서 잠열 방출의 해석이 가능하다. 본 연구는 상변환시 수반되는 잠열의 방출 형태를 4개의 다른 모델을 사용하여 비정상 온도분포, 용융형태, 자연대류가 미치는 영향을 수치적으로 구하였다. 2개의 서로 다른 물성치를 가진 합금을 선택하였는데 하나는 넓은 mushy 영역을 가진 알루미늄 합금이고 다른 하나는 좁은 mushy 영역을 가진 철금속계 합금이다. 알루미늄 합금의 경우 온도 분포와 시간에 따른 온도의 변화가 모델에 따라 상당한 차이가 있는 반면 철금속계 합금의 경우 상이한 모델일지라도 거의 차이가 없음을 알 수 있었다. 결론으로 용융시 정확한 온도 분포와 상변화 형태를 예측하기 위해서는, 알루미늄 합금(넓은 mushy 영역)의 경우 적절한 잠열 방출 모델의 채택이 필요 불가급한 것으로 사료된다.

• Journal of Korea Foundry Society
• /
• v.12 no.1
• /
• pp.51-61
• /
• 1992

주조시 주형내의 유동해석을 위해서는 시간에 따라 변화하는 자유표면 위치에 대한 정확한 정보가 요구되는 관계로 난제로 여겨져 왔다. 따라서 대부분의 연구는 초기치 속도를 정의하기 위해서 순간충입(instantaneous filling)을 가정하여 수치 해석을 하였던 것이다. 본 연구는 Modified Solution Algorithm-Volume of Fluid Method (MSOLA-VOF)를 개발하는 주조시 주형내의 유동을 수치적으로 해석하며, 유속이 수평 주조, 수직 주조의 경우에 어떤 영향을 미치는가에 대하여 연구하였다. 결론으로 응고 연구에 있어서 초기의 순간충입은 비현실적인 가정이라는 것이 밝혀졌으며, 충입시 초기 속도 분포와 결정 생성은 밀접한 관계가 있음을 알 수 있었다.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.863-874
• /
• 2009

The engineering characteristics and the reinforcement effect of the elephant foot method were discussed with parametric study. The elephant foot method is adopted to support the loads transferred from tunnel crown and improve bearing capacity of elephant foot in poor ground condition. The evaluation of reinforcement effect, which has the mechanical relationship between ground condition, footing size and reinforcement system, was carried out through the previous research and numerical analysis. In addition, the simple design chart was proposed to estimate the applicability of the elephant foot reinforcement method. It will be practical for the engineer to determine the optimum reinforcement method for safe tunnelling in soft ground condition.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.264-267
• /
• 2004

Wall thinning of carbon steel pipe components due to Flow-Accelerated Corrosion (FAC) is one of the most serious threats to the integrity of steam cycle piping systems in Nuclear Power Plants (NPP). Since the mid-1990s, secondary side piping systems in Korean NPPs have experienced wall thinning, leakages and ruptures caused by FAC. Korea Electric power Research Institute (KEPRI) and Korea Hydro & Nuclear Power Co., LTD. (KHNP) have conducted a study to develop the methodology for systematic pipe management and established the Korean Thinned Pipe Management Program (TPMP). To effectively maintain the integrity of piping system, FAC engineer should understand the criterions of the structural integrity evaluation and the safety margin assessment for the thinned pipe component. This paper describes the technical items of TPMP, and shows the example of the integrity evaluation and safety margin assessment for three thinned pipe component of a NPP.

• 제어로봇시스템학회:학술대회논문집
• /
• 1998.10a
• /
• pp.205-209
• /
• 1998

A synthesis of fuzzy variable structure control is proposed to design a high-angle-of-attack flight system for a modification version of the F-18 aircraft. The knowledge of the proportional, integral, and derivative control is combined into the fuzzy control that addresses both the highly nonlinear aerodynamic characteristics of elevators and the control limit of thrust vectoring nozzles. A simple gain scheduling method with multi-layered fuzzy rules is adopted to obtain an appropriate blend of elevator and thrust vectoring commands in the wide operating range. Improving the computational efficiency, an accelerated kernel for on-line fuzzy reasoning is also proposed. The resulting control system achieves the good flying quantities during a high-angle-of- attack excursion. Thus the fuzzy logic can afford the control engineer a flexible means of deriving effective control laws in the nonlinear flight regime.