• Proceedings of the Korean Institute of Interior Design Conference
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• 2002.04a
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• pp.66-70
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• 2002

The purpose of this study was to identify the Korean traditional housing design characteristics in apartment model houses. 37 floor plans of apartment model houses in Busan were collected and analyzed. Also, 31 design element check-lists were checked through the field study in apartment model houses. The results were as follows: 1) Korean traditional housing design characteristics in aspects of space organization, such as harmony with nature, hierarchy, focal space, flexibility, were founded in apartment houses. 2) Korean traditional housing design characteristics in aspects of scale, material, color, and motif were mostly founded in the master bedroom and the living room in apartment house. 3) Also, the larger the size of apartment houses were, the more Korean traditional housing design characteristics were founded.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.98-103
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• 1998

Recently, DVD/CD compatible driver is needed for DVD and CD is widely used as a new optical data restoring device. The optical systems of DVD and CD driver are different because they have different optical feature. If only one objective lens is used, the change of an aperture or a dual focal length of the lens is required. This method, however, increases the number of parts and results in loss of the power of laser light. Hence, we propose a dual lens actuator design that can read DVD and CD respectively. Albeit magnetic spring is important mechanism in the dual lens actuator design, there has not been the systematic approach to design the mechanism in the preceding researches. In this article. the guideway to design magnetic spring is presented by using the qualitative theoretical approach and the finite element analysis.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.81-84
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• 1989

EHZP is a kind of holographic optical element, which is generated by the interference of two divergent spherical waves from point sources on the same axis. It has the spherical aberration that the focal power increases as the radial distance r increases. By using this property, optimal design of EHZP was performed for f-$\theta$ lens. As the result of optimization, the f-$\theta$ condition and the field flattening condition were well satisfied when EHZP has f0=0.803f, faR=4.076f, 1=0.406f. It was assumed for calculation of field flattening condition that the incident wave was a plane wave with the diameter of 1mm.

• International journal of advanced smart convergence
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• v.8 no.1
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• pp.133-140
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• 2019

In this paper, we present an algorithm for adjusting degree of belief for consistency on the evidence dependency network where various sets of evidence support different sets of hypotheses. It is common for experts to assign higher degree of belief to a hypothesis when there is more evidence over the hypothesis. Human expert without knowledge of uncertainty handling may not be able to cope with how evidence is combined to produce the anticipated belief value. Belief in a hypothesis changes as a series of evidence is known to be true. In non-monotonic reasoning environments, the belief retraction method is needed to clearly deal with uncertain situations. We create evidence dependency network from rules and apply the evidence retraction algorithm to refine belief values on the hypothesis set. We also introduce negative belief values to reflect the reverse effect of evidence combination.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.53.2-53.2
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• 2014

IGRINS, the Immersion GRating INfrared Spectrometer, is a near-infrared wide-band high-resolution spectrograph jointly developed by the Korea Astronomy and Space Science Institute and the University of Texas at Austin. IGRINS employs three HAWAII-2RG focal plane array (FPA) detectors. The mechanical mounts for these detectors serves a critical function in the overall instrument design: Optically, they permit the only positional compensation in the otherwise "build to print" design. Thermally, they permit setting and control of the detector operating temperature independently of the cryostat bench. We present the design and fabrication of the mechanical mount as a single module. The detector mount includes the array housing, a housing for the SIDECAR ASIC, a field flattener lens holder, and a support base. The detector and ASIC housing will be kept at 65 K and the support base at 130 K. G10 supports thermally isolate the detector and ASIC housing from the support base. The field flattening lens holder attaches directly to the FPA array housing and holds the lens with a six-point kinematic mount. Fine adjustment features permit changes in axial position and in yaw and pitch angles. We optimized the structural stability and thermal characteristics of the mount design using computer-aided 3D modeling and finite element analysis. Based on the computer simulation, the designed detector mount meets the optical and thermal requirements very well.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.452-465
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• 2016

In this study, the structure of a concave annular array transducer was optimized to generate high intensity focused ultrasound for medical therapeutic application. The transducer has a phased array structure composed of several concentric channels that have 40 mm as the radius of curvature. We derived theoretical equations to analyze the sound field of the transducer and verified the validity of the equations by comparing the results calculated by the equations with those from finite element analyses. We also checked the possibility of dynamic focusing at around the geometric focal point. Further, the level of a grating lobe occurring at an unwanted position in the transducer sound field was confirmed to be reducible through the relation between the number of channels and the frequency of the transducer. Hence, the structure of the transducer was optimized to place the main lobe within a specific range from the zenith while systematically reducing the level of the maximum sidelobe including the grating lobe. The designed structure showed the performance better than that targeted at all the focal points.

• The Journal of the Acoustical Society of Korea
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• v.34 no.4
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• pp.264-273
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• 2015

Improvement of the radiation beam profile of a medical ultrasonic transducer has been researched in this paper. In order to improve the beam profile, a new transducer structure has been devised that includes both a shaded electrode and a multi-focus lens. For a linear sound source, the beam profile was investigated through finite element analysis, and then the optimal design of the devised structure was carried out by considering such performances as sidelobe level, focal range and beamwidth simultaneously. In the process, the optimal dimension of the devised structure was derived by using the ratio of the focal range to the minimum beamwidth as a performance index. As a result, the beam profile has been improved to have a lower sidelobe level at -20.2 dB and a consistent narrow beamwidth from 30 mm to 160 mm depth with the minimum beamwidth at 2.04 mm. Further, a prototype transducer was fabricated to have the devised structure, and its performance was measured and compared with the analysis results to confirm the validity of the devised transducer structure.

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.643-658
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• 2018

In this paper, we introduce a new framework for running the finite element (FE) packages inside an online Loop together with MATLAB. Contrary to the Hardware-in-the-Loop techniques (HiL), in the proposed Software-in-the-Loop framework (SiL), the FE package represents a simulation platform replicating the real system which can be out of access due to several strategic reasons, e.g., costs and accessibility. Practically, SiL for sophisticated structural design and multi-physical simulations provides a platform for preliminary tests before prototyping and mass production. This feature may reduce the new product's costs significantly and may add several flexibilities in implementing different instruments with the goal of shortlisting the most cost-effective ones before moving to real-time experiments for the civil and mechanical systems. The proposed SiL interconnection is not limited to ABAQUS as long as the host FE package is capable of executing user-defined commands in FORTRAN language. The focal point of this research is on using the compiled FORTRAN subroutine as a messenger between ABAQUS/CAE kernel and MATLAB Engine. In order to show the generality of the proposed scheme, the limitations of the available SiL schemes in the literature are addressed in this paper. Additionally, all technical details for establishing the connection between FEM and MATLAB are provided for the interested reader. Finally, two numerical sub-problems are defined for offline and online post-processing, i.e., offline optimization and closed-loop system performance analysis in control theory.

• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.3-8
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• 2006

The demand fer small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased by using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable fur mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-replication process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the surface profiles of master, mold and molded pattern were measured by optical scanning profiler. The geometrical deviation between the master and the molded DOE was less than $0.1{\mu}m$. The diffraction efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was $84.5\%$.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.239-245
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• 2000

In this paper, the fundamental properties of diffractive optical element were investigated. Also, this work deals with theoretical approaches for achromatization in DOE's optical system based on thin lens theory. It is found that achromatization could be satisfied by one hybrid lens only, which is composed of a diffractive and a refractive element. In order to have compact optical system, we used the tele-photo type lens composed of a positive and a negative power elements instead of retro-focus lens. From the Gaussian brackets and Seidel aberration theory, the initial design was numerically obtained. The aberration properties of an initial design was aplanat and flat field. In order to correct the chromatic aberrations, refractive and diffractive elements were used on front element. This hybrid lens is also useful for correction of higher order aberrations. Compared to conventional design composed of refractive lenses only, this approach dramatically improved the compactness of the optical system. Finally, residual aberration balancing results in a lens with focal length of 3.89 mm and overall length of 5.19 mm, which has enough performance over an f-number of 4.0. Also, it is expected to fulfill all the requirements of a digital still camera lens. This optical system is superior to the current refractive lens system in the number of elements, weight, and aberration properties. rties.