• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.55-61
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• 2004

Leading front of a lifted diffusion flame in turbulent mixing layer was investigated in order to find a appropriate definition of the turbulent edge propagation speed. The turbulent lifted diffusion flame was simulated by employing the flame hole dynamics combined with level-set method which yields a temporally evolving turbulent extinction process. By tracing the leading front locations of the temporal flame edges, temporal variations of the liftoff height, local flow velocity, and edge propagation speed at the leading front were investigated and they demonstrated the flame-stabilization condition of the turbulent lifted flame. Finally, a turbulent edge propagation speed was defined and its temporal variation from the simulation was discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.2
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• pp.1-6
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• 1986

Even though it is well known that the tidal current in the East China Sea rotates clockwise, few report can be found about the precise pattern of it. To furnish some information available for the stow net fishermen, the author carried out the observation over 235 semidiurnal tidal cycle to investigate the pattern of the set and the rate of tidal current in the Korean fishing section 250 and 494, by reading the current meter and by tracing the corner reflectors with radar onboard the anchored obsen'ation vessel, from May 12, 1984 through February 27, 1986. The results obtained are as follows: 1. The mean semidiurnal tidal cycle was 12 h 20 m during spring tide, and 12 h 30 m during neap tide. 2. The mean interval from the calculated time of high water until the current began to set north was 2 h 30 m and 2 h 15 m in the fishing section 250 and 494 respectively, and the mean interval from the time of low water current began to set south was about 2 h 0 m in both sections. 3. In comparison of the occupied times to vary the set from one of 8 principal bearing points to the neighboring one, the shortest was while the set varied from N to NE and S to SW in the section 250 and 494 respectively. Contrary the longest was while the set varied from SE to S and from W to NW in the section 250 and 494 respectively. 4. In comparison of the rate while the set varied from one of 8 principal bearing points to the neighboring one, the fastest was while the set varied from SE to Sand NW to N in the section 250, and E to SE and W to NW in the section 494. Contrary the slowest was while the current set to NE and S W in the section 250, and N, NE and S W in the section 494.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.859-867
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• 2002

Radiative transfer in energy systems such as furnaces, combustors, boilers and high temperature machineries is a significant mode of heat transfer. Although there are many solution schemes suggested for analysis of radiative transfer in multi-dimensional systems, the applicabilities and accuracies of these schemes have not fully tested for nongray gases. Especially reference data for enclosures of non-orthogonal shapes are not yet enough. In this paper we present some precise radiative transfer solutions for a black walled 3-dimensional cylindrical system filled with nongray gases. The SNB(statistical narrow band) model and the ray-tracing method with the T$_{N}$ quadrature set are used for finding nongray solutions. Although the solution method used in this study is not suitable for engineering purposes, the resulting solutions are proved to be quite accurate and can be regarded as the exact solutions and the results presented in this paper can be used in developing various solution schemes fur radiative transfer by real gas mixtures.s.

• Journal of Welding and Joining
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• v.23 no.2
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• pp.81-89
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• 2005

A numerical model for multiple reflection effects of a polarized beam on laser grooving has been developed. The surface of the treated material is assumed to reflect laser irradiation in a fully specular fashion. Combining electromagnetic wave theory with Fresnel's relation, the reflective behavior of a groove surface can be obtained as well as the change of the polarization status in the reflected wave field. The material surface is divided into a number of rectangular patches using a bicubic surface representation method. The net radiative flux far these patch elements is obtained by standard ray tracing methods. The changing state of polarization of the electric field after reflection was included in the ray tracing method. The resulting radiative flux is combined with a set of three-dimensional conduction equations governing conduction losses into the medium, and the resulting groove shape and depth are found through iterative procedures. It is observed that reflections of a polarized beam play an important role not only in increasing the material removal rate but also in forming different final groove shapes. Comparison with available experimental results for silicon nitride shows good agreement for the qualitative trends of the dependence of groove shapes on the electric field vector orientation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.743-750
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• 2003

With the expansion of computer technology the mobility of a mobile agent code having the flexibility in the dispersive computer situation is used to set up the applications distributed on the Internet. As it also has the ability to transmit the mobile code of a mobile agent and to receive it from a far-off host, the executive circumstances of the host system in which an agent is executed have to access to an agent code and the executive state capable of executing an agent code. Therefore, it is difficult to prevent the forgery, the alteration and the wrong execution of an agent from a malicious host. This dissertation suggests the mechanism which can protect an agent from the malicious action through the executive pursuit of a code-named mobile agent. The security of this mechanism is verified through the protective process of a mobile agent in this mechanism.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.6
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• pp.96-101
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• 2020

In this paper, we present the results of our research to perform 3D laser scanning functions by adding a focusing lens to a conventional 2D laser scanner. For the optical design, the ray-tracing technique was used along with a total of four lenses as the variable incident focusing lens, the collimating lens, and the F-Theta lens. As design variables, the curvature of the incident focusing lens (Lens #1) was assumed to be us, l mm and sumed mm, and the incident angles were set at 0cidenus, l. In addition, the distance between the focusing lens and the collimating lens was set to vary from 5 mm to 15 mm. When the incident focal length was varied from 5 mm to 15 mm, the exit focal length was calculated to vary from 67.5 mm to 56.8 mm for the lens with R = 100 mm and from 108.5 mm to 99.0 mm for the lens with R = 150 mm. When the incident angle was 0°, the focal aberration was only slightly observable at 10㎛ in both the x- and y-direction. At 7.5° was the focal aberration of approximately 20~50㎛ was measured at 20㎛. To investigate the chromatic aberration of the designed optical device, the distortion of the focus was observed when the 550 nm beam was simulated on lens designed for a 980 nm wavelength.

• The Research Journal of the Costume Culture
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• v.12 no.2
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• pp.290-299
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• 2004

The purpose of this study is to testify the pattern making method to develop the men's basic bodice pattern using 3-dimensional body scan data. The experimental patterns were made by adding wearing ease on flattened body scan data and tracing the outlines of it. The experimental bodice pattern were composed of front, back, and side panels. To compare the difference between the experimental pattern and traditional pattern, two pattern making methods were compared. Two sets of basic bodice patterns were made for each of the 10 male subjects: a set of pattern was made by experimental method and the other set was made by Bunka pattern making method. The experimental and traditional patterns were measured at 13 dimensions. The results show that there was a difference between the experimental patterns and traditional patterns at the front length, back length, front width, front neck width, back neck width, and back neck depth. The fit was also compared for both patterns. The results of the fit test show that the experimental patterns were superior to the traditional patterns at the fit of neck, shoulder, and armhole. The experimental pattern making method was expected to be useful for mass customization.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.614-622
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• 2016

In this paper, we propose a novel differential equation method for designing a total internal reflection (TIR) LED lens with double freeform surfaces. A complete set of simultaneous differential equations for the method is derived from the condition for minimizing the Fresnel loss, illumination models, Snell’s Law of ray propagation, and a new constraint on the incident angle of a ray on the light-exiting surface of the lens. The last constraint is essential to complete the set of simultaneous differential equations. By adopting the TIR structure and applying the condition for minimizing the Fresnel loss, it is expected that the proposed TIR LED lens can have a high luminous flux efficiency, even though its beam-spread angle is narrow. To validate the proposed method, three TIR LED lenses with beam-spread angles of less than 22.6° have been designed, and their performances evaluated by ray tracing. Their luminous flux efficiencies could be obviously increased by at least 35% and 5%, compared to conventional LED lenses with a single freeform surface and with double freeform surfaces, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.641-644
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• 2005

This study reveals some recent attempt in modeling empirically obtained B&K HATS (Head and Torso Simulator) HRTFs (Head Related Transfer Functions) to Isolate parameters that stimulate lateral and elevation perception. Localization using non-individual HRTFs often yields poor performance in synthesizing virtual sound sources when applied to a group of individuals due to differences in size and shape of head, pinnae, and torso. For realization of both effective and efficient virtual audio it is necessary to develop a method to tailor a given set of non-individual HRTFs to fit each listener without measuring his/her HRTF set. Pole-zero modeling is applied to fit HRIRs (Head Related Impulse Responses) and modeling criterions for determining suitable number of parameters are suggested for efficient modeling. Horizontal HRTFs are modeled as minimum-phase transfer functions with appropriate ITDs (Interaural Time Delay) obtained from RTF (Ray Tracing Formula) to better fit the size of listener's head for usage in simple virtualizer algorithms without complex regularization processes. Result of modeling HRTFs in the median plane is shown and parameters responsible for elevation perception are isolated which can be referred to in the future study of developing customizable HRTFs.

• The KIPS Transactions:PartD
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• v.19D no.2
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• pp.203-210
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• 2012

Capture-and-replay technique is a common automatic method for GUI testing. Testing applications on Android platform cannot use directly capture-and-replay technique due to the testing framework which is already set up and technical supported by Google and lack of automatic linking GUI elements to actions handling widget events. Without capture-and-replay testing tools testers must design and implement testing scenarios according to the specification, and make linking every GUI elements to event handling parts all by hand. This paper proposes a more improved and optimized approach than common capture-and-replay technique for automatic testing Android GUI widgets. XML is applied to extract GUI elements from applications based on tracing the actions to handle widget events. After tracing click events using monitoring in capture phase test cases will be created by communicating status of activated widget in replay phase with API events.