• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.12
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• pp.55-64
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• 2014

This paper presents a case study to investigate the monthly calculation method of ISO 13790 applied for a office building. The energy performance analysis according to improvement of insulation and air permeability of windows in K office buildings is investigated by means of building energy efficiency rating tool ($ECO_2-OD$). The K building energy system is tested experimently by the measurement of PMV(predicted mean vote) for the control of indoor thermal environment and heat transmission coefficient of windows and interior walls respectively, before and after the example K office building is remodeled passively. Therefore, Internet based energy assessment program of energy efficiency rating of office building can be applied as a program for the annual energy requirement and for evaluation of energy savings from the experimental and simulation results.

• International Journal of Fluid Machinery and Systems
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• v.9 no.2
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• pp.129-136
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• 2016

An experimental investigation was carried out to improve the performance of a counter-rotating type horizontal-axis tidal stream power unit. Front and rear blades were designed separately based on modified blade element momentum (BEM) theory, and their performances at different conditions of blade tip speed ratio were measured in a wind tunnel. Three different groups of blades were designed successively, and the results showed that Group3 possessed the highest power coefficient of 0.44 and was the most satisfactory model. This experiment shows that properly increasing diameter and reducing chord length will benefit the performance of the blade.

• Tribology and Lubricants
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• v.22 no.2
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• pp.87-92
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• 2006

In tread brake of freight cars, brake force is produced by the friction between the wheel and the brake shoe. Friction coefficients associated with the brake power, weight variation and brake shoe types should be sensitively treated as the design parameters. The conditions of the car, empty and loaded, should also be taken into consideration in brake force design and the control of brake force has some limitations in terms of the brake system design so that the brake friction materials selection should be considered as important measures to solve that difficulties. Friction characteristics of brake friction materials should remain within the range of maximum and minimum value and the friction performance should remain stable regardless of brake time and temperature. This study presented an experimental evaluation method to secure optimum brake performance by keeping safe brake effect and brake distance by the friction coefficient of the brake shoe of the freight cars.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.377-382
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• 2003

In tread braking of freight cars, braking force is produced by the friction between the wheel and the braking shoe. Friction coefficients such as the brake power, weight variation and brake shoe types should be sensitively treated as the design parameters. The conditions of the car, empty and weighted, should also be taken into consideration in brake force design and the control of brake force has some limitations in terms of the brake system design so that the brake materials selection should be considered as important measures to solve that difficulties. Friction characteristics of brake materials should remain within the range of maximum and minimum value and the friction performance should remain stable regardless of braking time and temperature. This study presented an experimental evaluation method to secure optimum braking performance by keeping safe braking effect and braking distance by the friction coefficient of the brake shoe of the freight cars.

• Journal of Auto-vehicle Safety Association
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• v.5 no.2
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• pp.17-23
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• 2013

This paper describes an algorithm for Advanced Emergency Braking(AEB) with tire-road friction coefficient estimation. The AEB is a system to avoid a collision or mitigate a collision impact by decelerating the car automatically when forward collision is imminent. Typical AEB system is operated by Time-to-collision(TTC), which considers only relative velocity and clearance from control vehicle to preceding vehicle. AEB operation by TTC has a limit that tire-road friction coefficient is not considered. In this paper, Tire-road friction coefficient is also considered to achieve more safe operation of AEB. Interacting Multiple Model method(IMM) is used for Tire-road friction coefficient estimation. The AEB algorithm consists of friction coefficient estimator and upper level controller and lower level controller. The numerical simulation has been conducted to demonstrate the control performance of the proposed AEB algorithm. The simulation study has been conducted with a closed-loop driver-controller-vehicle system using using MATLAB-Simulink software and CarSim Vehicle model.

• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.40-45
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• 2007

This study was performed to investigate the effect of various propeller tunnel shapes on the propulsion performance of a fishing boat. The propeller tunnel reduces the problem resulting from the open propeller accidentally catching the waste net and cable on the sea, as well as increasing the cruising speed. For 3 different tunnel geometries, the model test is conducted in the circular water channel, and the potential based panel method was applied to analyze the hydrodynamic characteristics of propeller. Also, both results are compared with each other to represent the difference between results of the model scale test and the potential theory. It is expected that these results could be referenced in the design of the propeller tunnel in consideration of the hydrodynamic interaction between the propeller and the tunnel.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.915-922
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• 2008

The gas separation technology using membrane is widely used to refine various gases in many industry fields and recently is being applying in $CO_2$ recovery technology. In the gas and chemical tanker. nitrogen generators for inerting, purging and padding are on board and most of them have membrane modules of hollow fiber type with long life and vibration resisting properties. Because a membrane module is a key component accounting for 50% of total manufacturing cost of nitrogen generator, adequate selection for it is an important problem. In this paper, the flow performance coefficient based on dimension and specification data of membrane module was relatively selected to compare nitrogen generating capacity of module and various performance tests about the selected PARKER ST6010 membrane module were conducted. As a result, the useful coefficient and basic data in selecting a membrane module were achieved.

• Journal of the Korea Society for Simulation
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• v.14 no.4
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• pp.9-18
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• 2005

In this paper, the system is implemented in four ways , For those who want to learn Chinese characters using the internet, and To make the learning more interesting and entertaining. Four different learning methods have been provided , using the transition process of Chinese characters, games, animations, and an illustration of the relationships between Chinese Characters and korean letters. The subjects of the evaluation were freshmen polled about the Chinese character learning system. The evaluation methods are : the validity of the research content is evaluated using the Cronbach's coefficient alpha and the performance of the system is evaluated by F-type of Analysis of variance.

• Structural Engineering and Mechanics
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• v.17 no.5
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• pp.671-690
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• 2004

A meshless method with novel variation of point collocation by finite mixture approximation is developed in this paper, termed the meshless finite mixture (MFM) method. It is based on the finite mixture theorem and consists of two or more existing meshless techniques for exploitation of their respective merits for the numerical solution of partial differential boundary value (PDBV) problems. In this representation, the classical reproducing kernel particle and differential quadrature techniques are mixed in a point collocation framework. The least-square method is used to optimize the value of the weight coefficient to construct the final finite mixture approximation with higher accuracy and numerical stability. In order to validate the developed MFM method, several one- and two-dimensional PDBV problems are studied with different mixed boundary conditions. From the numerical results, it is observed that the optimized MFM weight coefficient can improve significantly the numerical stability and accuracy of the newly developed MFM method for the various PDBV problems.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.727-733
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• 2010

Optical tables provide a platform for the establishment and test of measurement systems which use Laser. Therefore, not only static characteristics such as surface flatness, static stiffness and etc. but dynamic response characteristics is very important design parameter. The dynamic stiffness is generally estimated through the modal test, and compliance is used as a representative performance standard. Recently there is an example of defining the dynamic deflection coefficient and using it as a new performance standard of the dynamic stiffness, but it is not generalized yet in industry. In this study, we verify the validity of existing DDC calculus by making an experiment on granite. And for improvement in damping performance of optical tables, we are going to evaluate the effect of fillers on the compliance, then develop an epoxy adhesive based on the result of this experiment.