• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.6
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• pp.571-580
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• 2014

To address unsolved issues of change detection in animated choropleth maps, we proposed the concept of 'gross change detection' and performed an experiment that empirically verifies the incidence of change blindness stems from the 'magnitude of change (MOC)', spatial distribution in animated choropleth maps. We generated experimental materials using the change-characterization arrays and the global Moran's I. Participants had 108 cases of changing maps with time duration (1 to 3 sec) and had questions. The results showed that MOC and duration affect gross change detection, but the most interesting result from our experiment was that different spatial distributions between two adjacent choropleth maps may lead the map reader to under- or over-estimate the level of gross change in the map. It implies that we should consider spatial distribution of change when we design animated choropleth maps.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.49.1-49.1
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• 2016

Asteroid taxonomy dates back to the mid-1970's and is based mostly on broadband photometric and spectroscopic observations in the visible wavelength. Different taxonomic classes have long been characterized by spectral slope shortward of 0.75 microns and the absorption band in 1 micron, the principal components. In this way, taxonomic classes are grouped and divided into four broad complexes; silicates (S), carbonaceous (C), featureless (X), Vestoids (V), and the end-members that do not fit well within the S, C, X and V complexes. The past decade witnessed an explosion of data due to the advent of large-scale asteroid surveys such as SDSS. The classification scheme has recently been expanded with the analysis of the SDSS 4th Moving Object Catalog (MOC 4) data. However, the boundaries of each complex and subclass are rather ambiguously defined by hand. Furthermore, there are only few studies on asteroid taxonomy using Johnson-Cousins filters, and those were conducted on a small number of objects, with significant uncertainties. In this paper, we present our preliminary results for a new taxonomic classification of asteroids using SMASS, Bus and DeMeo (2014) and the SDSS MOC 4 datasets. This classification scheme is simply represented by a triplet of photometric colors, either in SDSS or in Johnson-Cousins photometric systems.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.448-448
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• 2000

This paper deals with dynamic behaviour analysis for pipeline inspection gauge (PIG) flow control in natural gas pipeline. The dynamic behaviour of the PIG is depending on the different Pressure between the rear and nose parts, which is generated by injected gas flow behind PIG's tail and expelled gas flow in front of its nose. To analyze the dynamic behaviour characteristics such as gas flow in pipeline, and the PIG's position and velocity, mathematical model is derived as two types of a nonlinear hyperbolic partial differential equation for unsteady flow analysis of the PIG driving and expelled gas, and nonhomogeneous differential equation for dynamic analysis of PIG. The nonlinear equation is solved by method of characteristics (MOC) with the regular rectangular grid under appropriate initial and boundary conditions. The Runge-Kuta method is used when we solve the steady flow equations to get initial flow values and the dynamic equation of PIG. The gas upstream and downstream of PIG are divided into a number of elements of equal length. The sampling time and distance are chosen under Courant-Friedrich-Lewy (CFL) restriction. The simulation is performed with a pipeline segment in the Korea Gas Corporation (KOGAS) low pressure system, Ueijungboo-Sangye line. The simulation results show us that the derived mathematical model and the proposed computational scheme are effective for estimating the position and velocity of PIG with different operational conditions of pipeline.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.618-622
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• 2017

Gasoline is a widely used product as a source for energy in homes, the automotive industry, and for industrial power generation, and it is also a product with a high risk of fire and explosion. In this study, to examine the risk for explosion for gasoline, PG, MG and RG, which are categorized according to octane number, were used as test specimens to measure their explosion limit according changes in oxygen concentration. The explosion limit for 21% oxygen concentration in air were confirmed to be 1.5~10.9%, 1.4~8.1%, and 1.3~7.6%, respectively, and the MOC for each of the test sample were confirmed to be 10.9%. The explosion limit measured in the test performed in this study confirmed between a 1.2%~7.6% wider explosion limit for the currently accepted MSDS for gasoline, and therefore it is considered that the results of this study can provide significant reference for preventing fires and explosions for process used gasoline.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.1-9
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• 2002

This paper presents simple models for flow and the PIG dynamics when it passes through a $90^{\circ}$ curved section of pipeline. The simulation has been done with two different operational boundary conditions. The solution fur non-linear hyperbolic partial equations for flow is given by using MOC. The Runge-Kuta method is used to solve the initial condition equation fur flow and the PIG dynamics equation. The simulation results show that the proposed model and solution can be used fur estimating the PIG dynamics when the pig runs in the pipeline including curved section. In this paper, dynamic modeling and its analysis for the PIG flow through $90^{\circ}$ curved pipe with compressible and unsteady flow are studied. The PIG dynamics model is derived by using Lagrange equation under assumption that it passes through 3 different sections in the curved pipeline such that it moves into, inside and out of the curved section. The downstream and up stream flow dynamics including the curved sections are solved using MOC. The effectiveness of the derived mathematical models is estimated by simulation results fur a low pressure natural gas pipeline including downward and upward curved sections. The simulation results show that the proposed model and solution can be used for estimating the PIG dynamics when we pig the pipeline including curved section.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.116-120
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• 2001

The impactive Pressure wave induced by pyro valve in the pressurization system of KSR-III may result in fatal failure or malfunction of valves, so it is important to know the pressure wave characteristic in the pressurization system. An unsteady flow analysis in the simplified pressurization system was peformed by Finite difference method.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.17-24
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• 2019

The combustion properties of the flammable substance used in industrial fields include lower/upper flash point, lower/upper explosion limit, autoignition temperature(AIT), fire point, and minimum oxygen concentration(MOC) etc.. The accurate assessment of these characteristics should be made for process and worker safety. In this study, tert-amylalcohol(TAA), which is widely used as a solvent for epoxy resins, oxidizers of olefins, fuel oils and biomass, was selected. The reason is that there are few researches on the reliability of combustion characteristics compared to other flammable materials. The flash point of the TAA was measured by Setaflash, Pensky-Martens, Tag, and Cleveland testers. And the AIT of the TAA was measured by ASTM 659E. The lower/upper explosion limits of the TAA was estimated using the measured lower/upper flash points by Setaflash tester. The flash point of the TAA by using Setaflash and Pensky-Martens closed-cup testers were experimented at 19 ℃ and 21 ℃, respectively. The flash points of the TAA by Tag and Cleveland open cup testers were experimented at 28 ℃ and 34 ℃, respectively. The AIT of the TAA was experimented at 437 ℃. The LEL and UEL calculated by using lower and upper flash point of Setaflash were calculated at 1.10 vol% and 11.95 vol%, respectively.

• Journal of Power System Engineering
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• v.8 no.1
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• pp.24-29
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• 2004

In this study, a computer analysis has been developed for predicting the pipe pressure of the intake and exhaust manifold. To obtain the boundary conditions for a numerical analysis, one dimensional and non-steady gas dynamic calculation is performed by using the MOC(Method Of Characteristic). The main numerical parameters are the variation of the engine revolution to calculate the pulsating flow which the intake and exhaust valves arc working. The comparison of exhaust pressure in case of numerical results is quite matched with in case of experimental results. When engine revaluation is increased, the pressure amplitude showed a high value, but the pressure frequency was decreased.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.185-186
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• 2002

Fretting of fuel rod cladding material, Zircaloy-4 tube, in PWR nuclear power plants must be reduced and avoided. Nowadays the introduction of surface treatments or coatings is expected to be an ideal solution to fretting damage since fretting is closely related to wear. corrosion and fatigue. Therefore. in this study the fretting wear experiment was performed using TiAlN coated Zircaloy-4 tube as the fuel rod cladding and uncoated Zircaloy-4 as on of grids, especially concentrating on the sliding component. Fretting wear resistance of TiAlN coated Zircaloy-4 tubes was improved compared with that of TiN coated tubes and uncoated tubes and fretting wear mechanisms were brittle fracture and plastic flow at lower slip amplitude but severe oxidation and spallation of oxidative layer at higher ship amplitude.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.481-484
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• 2004

이 논문에서는 소포 배달 서비스를 위한 인텔리전트 모니터링 시스템(Intelligent Monitoring and Control System; IMCS)에 대해 기술한다. IMCS 는 GIS, GPS 그리고 무선 통신 기술을 이용하여 택배의 접수와 배달 업무를 효율적이고 효과적으로 개발하기 위한 시스템이다. IMCS는 모두 세개의 서브 시스템으로 구성되어 있는데 접수와 배달 계획을 수립하는 PDPS(Pick-up and Delivery Planning System)과 접수/배달 현황과 차량의 위치를 파악할 수 있는 PDMS(Pick-up and Delivery Monitoring System), 그리고 개인휴대단말기(PDA)을 이용한 실시간 업무 처리 시스템인 MOCS(Mobile Operations and Communication System)으로 구성되어 있다. PDPS는 GIS와 최적화 알고리즘을 이용하여 접수와 배달을 위한 방문 순서와 경로 그리고 고객에게 방문할 예정시간 등을 생성한다. MOCS에서는 GPS와 무선 통신을 이용하여 업무 중 발생한 접수/배달 결과와 위치 정보를 실시간으로 PDMS에 전송하고 바코드 스캐닝과 전자 서명 등의 업무를 지원한다. PDMS에서는 수신한 정보에 따라 소포의 접수/배달 현황과 차량의 위치를 전자지도 상에 표현하고 업무 차량의 이동 궤적을 표시하여 계획된 경로와 비교하여 모니터링하고 관제할 수 있다. 현재 IMCS는 국내 한 우체국에서 시범 운영되고 있다.