• Computational Structural Engineering
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• v.14 no.1
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• pp.40-48
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• 2001

• Journal of the korean Society of Automotive Engineers
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• v.16 no.5
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• pp.20-29
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• 1994

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.246-251
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• 2006

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.23-33
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• 2016

The current smart lighting is shaped to offer the lighting environment suitable for current context, after identifying user's action and location through a sensor. The sensor-based context awareness technology just considers a single user, and the studies to interpret many users' various context occurrences and conflicts lack. In existing studies, a fuzzy theory and algorithm including ReBa have been used as the methodology to solve context conflict. The fuzzy theory and algorithm including ReBa just avoid an opportunity of context conflict that may occur by providing services by each area, after the spaces where users are located are classified into many areas. Therefore, they actually cannot be regarded as customized service type that can offer personal preference-based context conflict. This paper proposes a priority-based LED lighting control system interpreting multiple context conflicts, which decides services, based on the granted priority according to context type, when service conflict is faced with, due to simultaneous occurrence of various contexts to many users. This study classifies the residential environment into such five areas as living room, 'bed room, study room, kitchen and bath room, and the contexts that may occur within each area are defined as 20 contexts such as exercising, doing makeup, reading, dining and entering, targeting several users. The proposed system defines various contexts of users using an ontology-based model and gives service of user oriented lighting environment through rule based on standard and context reasoning engine. To solve the issue of various context conflicts among users in the same space and at the same time point, the context in which user concentration is required is set in the highest priority. Also, visual comfort is offered as the best alternative priority in the case of the same priority. In this manner, they are utilized as the criteria for service selection upon conflict occurrence.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.14-23
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• 1998

The present study investigates numerically particle laden flow through compressor cascade. In general, a lot of turbine engines are affected by various particles which are suspending in the atmosphere. Especially in the case of aircraft aviating in volcanic, industrial and desert region including many particles, each components of engine system are damaged severely. That damage modes are erosion of compressor binding and rotor path components, partial or total blockage of cooling passage and engine control system degradation.. Initial damages can not be serious but cumulation of damages influences on safety of aircraft control and economical maintenance cost of engine system can be increased. When dust, materials and volcanic particles in the atmosphere flow in the compressor, it is necessary to predict damaged and deposited region of compressor blades. To the various flow inlet angle, predictions of particles trajectory in compressor cascade by Lagrangian method are presented and impulses by impaction of particles at blade surface are calculated. By the definition of particle deposition efficiency, characteristics of particles impact are considered quantitatively. With these prediction and experimental data, erosion rates are predicted for two materials - ceramic, soft metal - on compressor blade surface. Improvements like coating of blade surface could be found, by above prediction.

• Journal of the Korean Institute of Gas
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• v.18 no.1
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• pp.31-40
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• 2014

LNG storage outer tank is a vertically and horizontally prestressed concrete wall structure. Therefore, when the storage tanks become larger, prestressing tendons become longer and eventually the prestressing loss becomes larger. Also, recently, bomb terrors and accidental crashes have occurred frequently on important infrastructures. Therefore, LNG storage tanks are also exposed to these dangerous scenarios, where they need to be evaluated and protected from these threats. Therefore, in this study, the behavior of 270,000 kL LNG storage outer tank impacted by a flying object is evaluated using implicit FEM code, LS-DYNA. In the analysis, the prestress loss due to the increased length of prestressing tendons from enlargement of outer tank is considered. A comparison study between the LNG tanks with and without prestress loss is performed to investigate the impact behavior and the effect of prestressing force change on the safety and serviceability prestressed concrete containment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.699-705
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• 2012

The role of a seat belt in a vehicle is to protect the driver from injury when a crash occurs. However when a large crash occurs, the driver slips forward and receives a strong impact. To prevent this situation, improvement of seat belts is essential. In this study, the new concept of a dynamic locking tongue (DLT) for seat belts is developed. The DLT device is used to reduce the impact to the driver's chest by tightening the webbing, so the driver is protected from severe injury in a large crash. First, a finite element model of the DLT device is created using SAMCEF and structural analysis is conducted with boundary conditions similar to those found in experiments. Then, the stress in the DLT device can be calculated. Second, the shape of the DLT device is optimized using the response surface analysis method in order to minimize the stress and weight. The validity of the optimization of the DLT device is verified using structural analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.206-206
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• 2003

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.885-892
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• 2015

In this study, we simulate the railway crash accident that occurred at the Sangwangsimni station on the Seoul Metro Line #2, and we propose a solution to minimize the damage. We use LS-DYNA, which is the commercial software employed for collision analysis to perform 1-D and 3-D simulations for the recurrence of accidents. By performing 1-D simulations, we analyze the load, displacement, absorbed energy of the couplers, and acceleration of vehicles, and we evaluate the safety in accidental collisions. By performing 3-D simulations, we analyze the deformation of the car and over-ridding. We propose methods to improve the safety in collisions involving railway vehicles, and we perform collision accident simulations to determine improvements when applying a high-performance energy absorber to the front car.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8966-8976
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• 2015

Unshielded posts on roadside are a critical hazard to the safety of impact vehicle to the posts. A crashworthy post is developed. In the first phase, it dissipates the impact energy by the linear momentum conservation principle while the plastic impact between the post and vehicle takes place, then, the second phase dissipation follows by the deformation of the energy absorbing modules embedded in the guide trough of the foundation. Simulations of impacts to a rigidly connected post and crashworthy post were made using LS-DYNA program, which demonstrated the danger of unshielded rigidly connected post and the effectiveness of the proposed crashworthy post to the 0.9ton-80km/h impact.