• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.4
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• pp.321-329
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• 2001

To establish systematic diagnosis and treatment planning of dentofacial deformity patient including facial asymmetry or hemifacial microsomia patient, comprehensive analysis of three dimensional structure of the craniofacial skeleton is needed. Even though three dimensional CT has been developed, landmark identification of the CT is still questionable. In recent, a method for correcting cephalic malpositioning that enables accurate superimposition of the landmarks in different stages without using any additional equipment was developed. It became possible to compare the three-dimensional positional change of the maxillomandible without invasive procedure. Based on the principle of the method, a new program was developed for the purpose of diagnosis and treatment planning of dentofacial deformity patient via three dimensional visualization and structural analysis. This program enables us to perform following menu. First, visualization of three dimensional structure of the craniofacial skeleton with wire frame model which was made from the landmarks observed on both lateral and frontal cephalogram. Second, establishment of midsagittal plane of the face three dimensionally, with the concept of "the plane of the best-fit". Third, examination of the degree of deviation and direction of deformity of structure to the reference plane for the purpose of establishing surgical planning. Fourth, simulation of expected postoperative result by various image operation such as mirroring, overlapping.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.149-159
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• 1998

The reasonable prediction of time-dependent deformation of prestressed concrete(PSC) box girder bridges is very important for accurate construction as well as good serviceability. The long-term behavior is mostly influenced by the probabilistic characteristic of creep and shrinkage. This paper presents a method of statistical analysis and sensitivity analysis of creep and shrinkage effects in PSC box been taken into account - model uncertainty, parameter variation and environmental condition. The statistical and sensitivity analyses are performed by using the numerical simulation of Latin Hypercube sampling. For each sample, the time-dependent structural analysis is performed to produce response data, which are then statistically analyzed. The probabilistic prediction of the confidence limits on long-term effects of creep and shrinkage is then expressed. Three measure are examined to quantify the sensitivity of the outputs of each of the input variables. These are rank correlation coefficient(RCC), partical rank correlation coefficient(PRCC) and standardiozed rank regression coefficient(SRRC) computed on the ranks of the observations. Three creep and shrinkage models - i. e., ACI model. CEB-FIP model and the model in Korea Highway Bridge Specification - are studied. The creep model uncertainy factor and the relative humidity appear to be the most dominant factors with regard to the model output uncertainty.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.8-13
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• 2018

A fluid-structure interaction analysis should be performed to evaluate the behavior of the internal fuel and its influence in order to confirm the structural soundness of the fuel tank against external impacts. In the past, fluid-structure interaction analyses have been limited to the obtention of numerical simulation results due to the need for considerable computational resources and excessive computation time. However, recently, computer performance has been dramatically improved, enabling complex numerical analyses such as fluid-structure interaction analysis to be conducted. Lagrangian and Euler coupling methods and Lagrangian based analysis methods are mainly used for fluid-structure interaction analysis. Since both of these methods have their advantages and disadvantages, it is necessary to select the more appropriate one when conducting a numerical analysis. In this study, a numerical analysis of a crash impact test for a fuel tank is performed using ALE. The purpose of the numerical analysis is to estimate the possibility of failure of the fuel tank mounted inside the container when it is subjected to a crash impact. As a result of the numerical analysis, the fluid behavior inside the fuel tank is investigated and the stress generated in the fuel tank and the container structure is calculated, thereby enabling the possibility of fuel tank failure and leakage of the internal fluid to be evaluated.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.312-317
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• 2015

Seafarers can confront to evacuate from the ship with many reasons such as collision, grounding and fire accident. It believes that evacuation time from ship is very important element in order to increase survival rate in the contingency circumstance, however narrow and complex structure of ship is one of obstacle element against prompt evacuation. Taking into consideration the unique structure of ship compared to the structure of other facilities, speed of fire propagation on board ship is faster than the same size of other type facilities. Therefore, measures to prompt evacuation are required. But it comes with the behavioral constraints of the crews and passengers of the nature of operating in a complex structure with narrow vessels. Therefore, in this study, we propose a formula to be analyzed by theoretical approach and simulation methods to improve the survival rate for the crew and passenger of the ship through the ship's structural modification. We analyzed the temperature rise and visibility which are the most influential effects on the life safety in the event of fire by using a three-dimensional analysis of sight-only program Fire Dynamic Simulator (FDS) as analytical tools.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.307-320
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• 2013

This paper proposes a new hybrid support structure by the driven piles which removes disadvantages of the existing type of support structure for offshore wind turbines. The hybrid type of support structure is combined with concrete cone and steel shaft, and is supported not only by gravity type foundations but also by driven piles. For three dimensional analysis of the huge and thick concrete structure, a solid-shell element that is capable of exact modeling and node interpolations of stresses is developed. By applying wave theory of stream function and solid-shell element in XSEA simulation software for fixed offshore wind turbines, a quasi-static analysis and natural frequency analysis of proposed support structure are performed with the environmental condition on Southwest Coast in Korea. In the result, lateral displacement is not exceed allowable displacement and a superiority of dynamic behavior of new hybrid support structure is validated by natural frequency analysis. Consequently, the hybrid support structure presented in this study has a structural stability enough to be applied on real-site condition in Korea. The optimized structures based on the preliminary design concept resulted in an efficient structure, which reasonably reduces fabrication costs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.68-76
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• 2000

The stabilization control of Inverted Pendulum(IP) system is difficult because of its nonlinearity and structural unstability. Futhermore, a series of conventional techniques such as the pole placement and the optimal control based on the local linearizations have narrow stabilizable regions. At the same time, the fine tunings of their gain parameters are also troublesome. Thus, in this paper, an Evolving Neural Network Controller(ENNC) which its structure and its connection weights are optimized simultaneously by Real Variable Elitist Genetic Algorithm(RVEGA) was presented for stabilization of an IP system with nonlinearity. This proposed ENNC was described by a simple genetic chromosome. And the deletion of neuron, the according to the various flag types. Therefore, the connection weights, its structure and the neuron types in the given ENNC can be optimized by the proposed evolution strategy. And the proposed ENNC was implemented successfully on the ADA-2310 data acquisition board and the 80586 microprocessor in order to stabilize the IP system. Through the simulation and experimental results, we showed that the finally acquired optimal ENNC was very useful in the stabilization control of IP system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.561-574
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• 2018

In this study, regional variations and factors associated with prevalence of metabolic syndrome were grasped using GWR (geographically weighted regression) and methodologies for the efficient management of metabolic syndrome were then set up to resolve health inequalities. Based on the National Health Screening Statistical Yearbook published by the National Health Insurance Service (NHIS), community health survey (KCDC) and other governmental institutions, indicators of social structural and mediation factors related to the regional prevalence of metabolic syndrome were collected. First, the existence of indicators to measure variations in metabolic syndrome were confirmed with the collected data by calculating the EQ (extremal quotient) and CV (coefficient of variations). The GWR, which is able to take spatial variations into consideration, was then adopted to analyze the factors of regional variations in metabolic syndrome. The GWR analysis revealed that severity and management of the main causes need to be prioritized in accordance with the prevalence of metabolic syndrome. Consequently, the order of priority in management of regional prevalence of metabolic syndrome was established, and plans that can increase the effectiveness of management of metabolic syndrome were confirmed to be feasible.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.4
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• pp.393-399
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• 2017

In a reciprocating compressor, the piston and connecting rod are important parts. Excess mechanical stress on these parts may cause damage, and broken parts are expensive and difficult to replace. Therefore, it is necessary to analyze the mechanical stress affecting durability and longevity. The main purpose of this study was to identify locations of maximum stress on pistons and connecting rods. Based on dynamic calculation of the working process of a specific air compressor, an analysis of piston and connecting rod performance has been completed. A three-dimensional model for the air compressor's pistons and connecting rods was built separately, and FEM analysis of these components was carried out using a numerical method. The pistons were loaded by pressure which was changed according to crankshaft angle without thermal boundary conditions. The simulation results were used to predict and estimate stress concentration as well as the value of this stress on pistons and connecting rods. The maximum equivalent stress calculated are over 190 MPa on pistons and 123 MPa on connecting rods at crank angle $135^{\circ}$ and $225^{\circ}$ but these are under tensile yield strength. Besides, the calculated safety factors of connecting rods and pistons is higher than 1. Moreover, the results obtained can be used to provide manufacturers with references to optimize the design of pistons and connecting rods for reciprocating compressors.

• Journal of Technology Innovation
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• v.22 no.4
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• pp.145-164
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• 2014

Nuclear fusion is one of the most promising options for generating large amounts of carbon-free energy in the future. Major countries such as China, EU, and Japan have established a national plan for DEMO construction and they are implementing it. Korea has started a nuclear fusion research and development by the KSTAR project started in 1995. There are matured needs for a full-scale research and development initiatives to ensure competition with the major countries for DEMO as well as achieve the final goal to commercialize fusion energy. In this paper, we apply the TRL and AHP methods in order to identify the key technologies to conduct DEMO R&D. We propose the priorities of future R&D on DEMO by deriving a core technology in the field. At first, we review the scientific theory of fusion and trend of progress of DEMO activities in major countries. For previous studies, we review TRL and AHP methods to examine the technology classification system of DEMO and identify key technologies. We apply TRL method to identify readiness level of DEMO technologies and AHP to compensate shortcoming of TRL. The key technologies of DEMO to be secured from a synthesis result of the TRL and AHP are burning plasma, plasma facing material, structural material, high frequency heating, neutral particle beam, safety, plasma diagnostic, and simulation technologies.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.407-418
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• 2017

Due to geographical features of being close to DPRK (Democratic People's Republic of Korea), the Imjin River basin has difficulties in hydrological observation, and is vulnerable to unexpected flood occurrence. As a countermeasure, Gunnam Flood Control Reservoir construction was planned in 2005. Despite such a structural measure, damages by DPRK's illegal release continues to occur. Futhermore the Imjin River's flow has been decreased due to the effect of continuous drought in the Korean Peninsula since 2012 and DPRK's unilateral storage of water. A new operation method is derived for the Gunnam Flood Control Reservoir in order to cope with drought damages on the Imjin River basin and to ensure efficient response time upon flooding. The operation method maintaining Gunnam Flood Control Reservoir's water level by raising from EL.23.0 m to EL.31.0 m during the flood season for securing reservoir capacity enables to secure additional $14,000,000m^3$ water compared to the existing operation methods. The operation method to store inflow by controlling release to $250m^3/s$ in the early stage of flood has increased 2.66% on average in terms of detention effect of reservoir compared to the existing operation methods. The method enables to secure 19 hours to prepare flood compared to the existing methods.