• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.53-62
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• 1994

This paper presents a new approach of analyzing errors resulting from nonideal general-purpose lighting environment when the Photometric Stereo Method (PSM) is applied to estimate the surface-orientation of a three-dimensional object. The approach introduces the explicit modeling of the lighting environment including a circular-disk type irradiance object plane and the direct simulation of the error distribution with the model. The light source is modeled as a point source that has a certain amount of beam angle, and the luminance distribution on the irradiance plane is modeled as a Gaussian function with different deviation values. A simulation algorithm is devised to estimate the light source orientation computing the average luminance intensities obtained from the irradiance object planes positioned in three different orientations. The effect of the nonideal lighting model is directly reflected in such simulation, because of the analogy between the PSM and the proposed algorithm. With an instrumental tool designed to provide arbitrary orientations of the object plane at the origin of the coordinate system, experiment can be performed in a systematic way for the error analysis and compensation. Simulations are performed to find out the error distribution by widely varying the light model and the orientation set of the object plane. The simulation results are compared with those of the experiment performed in the same way as the simulation. It is confirmed from the experiment that a fair amount of errors is due to the erroneous effect of the general-purpose lighting environment.

• Journal of The Korean Association For Science Education
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• v.37 no.1
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• pp.39-48
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• 2017

In this study, we investigated the characteristics of analogs generated by high school students to explain ionic bonding in the perspectives of the number of analogs, the understanding of mapping, and the source and type of analogs. We also compared the results by students' conceptual understanding, logical thinking ability, and analogical reasoning ability. Participants in this study were 395 11th graders in Seoul. The results of the study showed that the higher the conceptual understanding, the logical thinking ability, and the analogical reasoning ability, the more the students generated the analogs. The understanding of mapping was related to logical thinking ability and analogical reasoning ability. It is noteworthy that the sources of analogs differed only depending on their conceptual understanding of the target concept among the cognitive variables studied. Students who had higher conceptual understanding also generated analogs from more diverse sources. Some types of the generated analogs were related to the cognitive variables. For examples, the students who had higher conceptual understanding and logical thinking ability generated more verbal/pictorial analogs. The types of analogs were not related to cognitive variables in terms of artificiality, abstraction, and systemicity. Educational implications of these findings were discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.196-201
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• 1995

The broadband and discrete sources of sound in small cooling fans of propeller type and centrifugal type were investigated to understand the turbulent vortex structures from many bladed fans using ANSI test plenum for small air-moving devices (AMDs). The noise measurement method uses the plenum as a test apparatus to determine the acoustic source spectral density function at each operating conditions similar to real engineering applications based on acoustic similarity laws. The characteristics of fans including the head rise vs. volumetric flow rate performance were measured using a performance test facility. The sound power spectrum is decomposed into two non-dimensional functions: an acoustic source spectral distribution function F(St,.phi.) and an acoustic system response function G(He,.phi.) where St, He, and .phi. are the Strouhal number, the Helmholtz number, and the volumetric flow rate coefficient, respectively. The autospectra of radiated noise measurements for the fan operating at several volumetric flow rates,.phi., are analyzed using acoustical similarity. The rotating stall in the small propeller fan with a bell-mouth guided is mainly due to a leading edge separation. It creates a blockage in the passage and the reduction in the flow rate. The sound power levels with respect to the rotational speeds were measured to reveal the mechanisms of stall and/or surge for different loading conditions and geometries, for example, fans installed with a impinging plate. Lee and Meecham (1993) studied the effect of the large-scale motions like impinging normally on a flat plate using Large-Eddy Simulation(LES) and Lighthill's analogy.[ASME Winter Annual Meeting 1993, 93-WA/NCA-22]. The dipole and quadrupole sources in the fans tested are shown closely related to the vortex structures involved using cross-correlations of the hot-wire and microphone signals.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.4
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• pp.425-433
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• 2001

A correlation between fatigue damage and acousto-ultrasonic (AU) parameters has been obtained from signals acquired during fatigue loading of the single-lap joints of a carbon-fiber reinforced plastic (CFRP) laminates and A16061 plate. The correlation showed an analogy to those representing the stiffness reduction $(E/E_0)$ of polymer matrix composites by the accumulation of fatigue damage. This has been attributed to the transmission characteristics of acoustic wave energy through bonded joints with delamination-type defects and their influence on the change of spectral content of AU signals. Another correlation between fatigue cycles and the spectral magnitude of acoustic emission (AE) signals has also been found during the final stage of fatigue loading. Both AU and AE can be applied almost in real-time to monitor the evolution of damage during fatigue loading.

• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.321-327
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• 2019

The purpose of this study is paper is to improve the flow performance and to reduce the aerodynamic noise of air discharge system consisting of a centrifugal fan, ducts and a housing for the clothes dryer. Using computational fluid dynamics and acoustic analogy based on FW-H (Ffowcs-Williams and Hawkings) Eq., air flow field and acoustic fields of the air discharge system are investigated. To optimize aerodynamic performance and aerodynamic noise, the response surface method is employed. The two factors central composite design using the inflow and outflow angles of fan blades is adopted. The devised optimum design shows the reduction of turbulent kinetic energy in the ducts and the housing of the system, and as a result, the improved flow rate and reduce noise is confirmed. Finally, the experment using the proto-type manufactured usign the optimum design shows the increase of flow rate by 4.2 %.

• Water for future
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• v.28 no.4
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• pp.185-194
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• 1995

The objective of this study is to explore scale problem and to analyze the relations between scale and geomorphologic parameters of the rainfall-runoff model. Generally, measurement and calculation of geomorphologic parameters rely on and are sensitive to the resolution of source information available. Therefore, rainfall-runoff models using geomorphologic parameters should take account of the effects of the map scale used in their development. The derived rainfall-runoff model considering scale problem in this research is the GIUH type model, that is a basin IUH consisting of the channel network response and hillslope response. The cannel network response is computed by means of the diffusion analogy transformed from linearized St. Venant equation and hillslope response is calculated by 2-parameter gamma distribution function. Representing geomorphologic structure of the channel network and initial distribution of its response is width function. This width function is derived by fractal theory and Melton's law to consider scale problems and is weighted by the source location function (SLF) proposed in this research to increase the applicability.

• The KSFM Journal of Fluid Machinery
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• v.4 no.3 s.12
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• pp.7-13
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• 2001

The present study investigates convective heat/mass transfer and flow characteristics inside a cooling passage of rotating gas-turbine blades. The rotating duct has staggered ribs with $70^{\circ}$ attack angle, which are attached on leading and trailing surfaces. Naphthalene sublimation technique is employed to determine detailed local heat transfer coefficients using the heat and mass transfer analogy. Additional numerical calculations are conducted to analyze the flow patterns in the cooling passage. The present experiments employ two-surface heating conditions in the rotating duct because the exposed surfaces to hot gas stream are pressure and suction side surfaces in the middle passages of an actual gas-turbine blade. Secondary flows are generated by Coriolis and centrifugal forces in the spanwise and streamwise directions. The ribs attached on the walls disturb the mainflow resulting in recirculation and secondary flows near the ribbed wall. The local heat transfer and flow patterns in the passage are changed significantly according to rib configurations and duct rotation speeds. Therefore, the geometry and arrangement of the ribs are important for the advantageous cooling performance. The experimental results show that the ribs enhance the heat transfer more than $70\%$ from that of the smooth duct. The duct rotation generates the heat transfer discrepancy between the leading and trailing walls due to the secondary flows induced by the Coriolis force. The overal heat transfer pattern on the leading and trailing walls for the first and second passes are depended on the rotating speed, but the local heat transfer trend is affected mainly by the rib arrangements.

• Transactions of the KSME C: Technology and Education
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• v.3 no.1
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• pp.1-13
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• 2015

In this study, a new dynamic VRF-type heat pump simulation model is proposed which incorporates frosting and defrosting models. Toward this end, a simple frosting model based on the perfect analogy, and lumped system based defrost model, are proposed. Then, frosting and defrosting models are incorporated into a dynamic heat pump model which adopts segment-by-segment local heat exchanger model and map-based variable speed compressor model. Thus, the model can naturally represent locally uneven frosting and defrosting on the heat exchanger surface. Developed simulation model is validated against available experimental data to show good agreement within 10% error for capacity and COP. Finally, developed dynamic heat pump model is applied to annual heating season simulation to show that seasonal COP of heat pump is degraded by 7% due to frosting and defrosting.

• Korean Institute of Interior Design Journal
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• v.18 no.5
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• pp.111-118
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• 2009

Urban houses of traditional Korean Style are a type of habitation that happened during a transitional period when the modernization of habitation had progressed in 1930s, and also a habitation folding societal trails that had adapted and developed into urbanization together with the native traits of traditional Korean Style houses. Because they keep our style of living and the process of change just as they were, it is important work to shed light on and keep a record of it. So, this thesis arranges the contents of research on the actual condition of living, and may try to reason by analogy the changing style of residents' living through the change of space composition and the way of space usage for the urban houses of traditional Korean style that were changed by extension and remodeling of residents. As the concrete matters, it is to grasp the physical and spatial change of urban houses of traditional Korean style in accordance with extension and remodeling, and to analyze in which part and how they had been changing for the spatial composition of urban houses of traditional Korean style according to the change of living style, and especially the change toward a stand-up type of k stand-and the following traits and factors of the change toward Dining-Kitchen. The kitchen changed toward Dining-Kitchen shows some typical discrepancies depending on the location of kitchen as like a case of changing toward Dining-Kitchen from the existing location, a case of extending into the rear side of kitchen, a case of switching of location between kitchen and the inner room, and a case of changing toward Dining-Kitchen from the location of a room across from the main living room. As kitchen changed toward Dining-Kitchen like these, it shows that the connecting trace into the inner room came out, each room came to show a bit clearer function but grow smaller relation with the threshing ground, and also the function of the threshing ground came reduced.

• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.273-281
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• 2012

Purpose: This study conducted a survey on the elderly of 65 years and over with physical debilities and ones capable of living at home residing in Jeju Special Self-Government Province to compare and analyze demo-sociological characteristics and factors influencing on oral health related living quality. And also this study intended to provide basic data for developing effective public medical policies and health promotion programs to increase oral health related living quality of the elder. Methods: The elderly of 65 years and over living in Jeju Special Self-Government Province were interviewed individually from 7 February 2011 to 18 April and interview results of a total of 220 subjects were analysed for this study. Results: Current status of the elderly including ones with & without physical debilities influenced functional limitation and behavioral aspects of GOHAI criteria used in this study. The elderly with physical debilities experienced less limitation in food chewing and swallowing, and pronunciation than ones capable of living at home. On the analogy of the previous study(by Park, N. G., 2010) in which oral health related quality and satisfaction of life of the elderly with physical debilities were different due to their physical, circumstantial and psychological limitations, the former's oral health conditions are worse than the ones capable of living at home and because of medical care accessability limitation they suffer from deteriorated oral condition. By the comparison of factors influencing on the living quality relating to the oral health of the elderly with physical debilities and ones capable of living at home, 2 factors, age and living area, were meaningful factors commonly influencing on the oral health related living qualities of both. The elderly of 75 years and over were more affected by psychological and behavioral aspects of oral health related living quality than the ones of 65-74 years, and the ones living in country suffered from functional limitations, pains and discomfort more than ones in city. Additionally, being different from the elderly capable of living at home, the ones with physical debilities were influenced by the factors of average monthly income and medical security type. Conclusion: Improvement of programs and systems to increase oral health related quality of life needs to be carried out preferentially for the elderly of 75 years and over, and dwelling in country. Also this study suggests that the policy of paying the denture insurance allowance in 2012 need effective planning considering the elderly's current status, age, living area, medical security type.