S. H. Kim

Kangwon National University, Gangneung, Gangwon, South Korea

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Publications (23)32.83 Total impact

  • S Y Park, S H Kim, Y J Kang
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    ABSTRACT: This article proposes an analytical method that can be used to obtain the vibro-acoustic modal and forced response characteristics of a three-dimensional structural—acoustic coupled system, where the coupled system is composed of an acoustic cavity with a rectangular plate that is stiffened by a local stiffener. Through the proposed method, the effect of the local stiffener on the natural frequencies, modes, and forced responses is identified for the plate—cavity coupled system with the local stiffener. The relationship between the thickness and the location of the local stiffener on the vibro-acoustic modal characteristics and forced responses is investigated through the structural—acoustic modal coupling coefficient. The high peak-noise due to the strong modal coupling between the plate and acoustic modes can be effectively reduced by properly designing the local stiffener in the coupled system. Finally, the modal characteristics and frequency responses obtained by the proposed method are compared with those of finite-element analysis. The results of this article provide useful information for suppressing the booming noise generated by the strong modal coupling between the plate and acoustic modes in the coupled system.
    ARCHIVE Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science 1989-1996 (vols 203-210) 01/2010; 1:1-17. · 0.63 Impact Factor
  • DN Kang, KI Jung, SH Kim, SH Jeon
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    ABSTRACT: Neurogenesis in Drosophila melanogaster is initiated by an ordered appearance of neuroblasts arranged in three columns (medial, intermediate, and lateral) in the neuroectoderm. In each column, specific homeodomain-containing genes are expressed. The ventral nervous system defective (vnd) regulates the fate of the cells in the medial domain of the neuroectoderm. In the present study, we identified Vnd-regulated genes through computational screening. Through further screening, we selected eight genes that were downregulated in the vnd loss-of function mutation. These included zfh1, uzip, CG7687, SytIV, stau, ase, scrt, and dpn genes. Ectopic expression of vnd, using the GAL4/UAS system, caused abnormal expression of all eight genes. Further, eight genes were coexpressed with that of vnd. Reverse-transcriptase polymerase chain reaction (RT-PCR) experiments showed an enhanced expression of uzip, CG7687, SytIV, and ase. Although the other four genes did not show an enhanced expression through RT-PCR, cytochemical and genetic evidence showed that these genes were regulated by Vnd. Taken together, the results obtained from this study indicate that expression of at least four genes, uzip, CG7687, SytIV, and ase, are regulated by Vnd.
    Journal of neurogenetics 05/2009; · 0.73 Impact Factor
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    H. G. Park, S. H. Kim, Y. J. Kang
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    ABSTRACT: In this research, we propose an analytical method to control the period and the clarity of the beat in a slightly asymmetric ring. The concept of a simple equivalent ring is applied, i.e. a slightly asymmetric ring with known modal data is modeled as an equivalent circular ring with one or multiple point masses, which has the same modal data as that of the original ring. By using the equivalent ring model, the optimal beat tuning is achieved by adding a 2nd point mass in order to obtain the required period and clarity in the beating vibration. The results obtained from the analytical method are compared with those obtained from finite element analysis(FEA) and the validity of the proposed method is verified. The proposed method can be effectively used to predict the mode pair and control the beat property in bell-type structures. KeywordsAsymmetric ring-Beat tuning
    Journal of Mechanical Science and Technology 01/2007; 21(8):1226-1234. · 1.09 Impact Factor
  • Advanced Materials 12/2006; 19(1):73 - 76. · 14.83 Impact Factor
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    ABSTRACT: We investigated resistance switching in top-electrode/ Ni O / Pt structures where the top electrode was Au, Pt, Ti, or Al. For Pt / Ni O / Pt and Au / Ni O / Pt structures with ohmic contacts, the effective electric field inside the film was high enough to induce trapping or detrapping at defect states and thus resistance switching. For a Ti / Ni O / Pt structure with well-defined Schottky contact at Ti / Ni O interface accompanied by an appreciable voltage drop, the effective electric field inside the NiO film was not enough to induce resistance switching. For an Al / Ni O / Pt structure with a low Schottky barrier at the Al / Ni O interface, resistance switching could be induced at a higher voltage since the voltage drop at the Al / Ni O interface was not negligible but small.
    Applied Physics Letters 01/2006; · 3.79 Impact Factor
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    ABSTRACT: We demonstrate room-temperature low-threshold-current lasing action from electrically driven wavelength-scale high-quality photonic crystal lasers having large spontaneous emission factors by solving the theoretical and technical constraints laid upon by the additional requirement of the current injection. The ultrasmall cavity is electrically pulse pumped through a submicron-size semiconductor “wire” at the center of the mode with minimal degradation of the quality factor. In addition, to better utilize the low mobility of the hole, we employ a doping structure that is inverted from the conventional semiconductors. Rich lasing actions and their various characteristics are experimentally measured in the single-cell and three-cell photonic crystal cavities. Several relevant measurements are compared with three-dimensional finite-difference time-domain computations based on the actual fabricated structural parameters. The electrically driven photonic crystal laser, which is a small step toward a “practical” form of the single photon source, represents a meaningful achievement in the field of photonic crystal devices and photonic integrated circuits as well as of great interest to the quantum electrodynamics and quantum information communities.
    IEEE Journal of Quantum Electronics 10/2005; · 2.11 Impact Factor
  • Journal- Korean Physical Society 09/2005; 47(92):243-. · 0.51 Impact Factor
  • Journal- Korean Physical Society 09/2005; 47(92):247-. · 0.51 Impact Factor
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    ABSTRACT: Conductivity switching phenomena controlled by external voltages have been investigated for various NiO films deposited by dc reactive sputtering methods. Pt/NiO/Pt capacitor structures with top electrodes of different diameters have showed increasing off-state current with the diameter of a top electrode and nearly the same on-state current independent of the diameter. Local conductivity switching behaviors have been observed in a series structure consisting of two Pt/NiO/Pt capacitors with different resistance values. By reasoning out conductivity switching mechanisms from the switching characteristics and introducing multilayers consisting of NiO layers with different resistance values, we have reduced the reset current by two orders of magnitude.
    Applied Physics Letters 02/2005; 86(9):093509-093509-3. · 3.79 Impact Factor
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    ABSTRACT: Negative resistance behavior and reproducible resistance switching were found in polycrystalline NiO films deposited by dc magnetron reactive sputtering methods. Oxygen to argon gas ratio during deposition was critical in deciding the detailed switching characteristics of either bi-stable memory switching or mono-stable threshold switching. Both metallic nickel defects and nickel vacancies influenced the negative resistance and the switching characteristics. We obtained a distribution of low resistance values which were dependent on the compliance current of high-to-low resistance switching. At 200 °C, the low-resistance state kept its initial resistance value while the high-resistance state reached 85% of its initial resistance value after 5×105 s. We suggested that the negative resistance and the switching mechanism could be described by electron conduction related to metallic nickel defect states existing in deep levels and by small-polaron hole hopping conduction.
    Applied Physics Letters 12/2004; 85(23):5655-5657. · 3.79 Impact Factor
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    ABSTRACT: We have successfully integrated 8M bits Localized ONO Memory (LONOM) for the embedded nonvolatile memory using 0.13um standard logic process with 5-level Cu metallization. which has a small cell size of 0.276UM and the simplest cell array structure. Without any special algorithm, the localized storage layer of the LONOM can satisfy the essential features for an embedded memory solution, such as low program current. disturb-free read operation and good endurance characteristics. The read speed is as high as 60MHz at V<sub>cc</sub>=0.9V, 85°C and the current consumption is lower than 5mA at Vcc = 1.4V.
    VLSI Technology, 2004. Digest of Technical Papers. 2004 Symposium on; 07/2004
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    C. B. Jeong, S. H. Kim
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    ABSTRACT: This paper presents a system for the segmentation of a printed document image into word images, which can be used effectively for document image retrieval based on keyword spotting. The system is composed of three image manipulation modules: skew correction, document layout analysis, and word segmentation. To enhance the practical applicability and flexibility of our research results, we test the system with 50 images of Korean papers and 50 images of English papers provided through full-text image retrieval services by the Korea Information Science Society and the Pattern Recognition Society, respectively. Currently, the accuracy of word extraction ranges from 90 to 95%, depending on the language of the document.
    Digital Libraries: International Collaboration and Cross-Fertilization, 7th International Conference on Asian Digital Libraries, ICADL 2004, Shanghai, China, December 13-17, 2004, Proceedings; 01/2004
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    ABSTRACT: A new Local SONOS structure has been proposed for an embedded NVM cell in 0.13 μm standard CMOS logic process. The localized storage silicon nitride layer of Local SONOS cell provides the essential properties for the embedded NVM such as the complete erase, low program current, and high on cell current from the low threshold voltage. The entire embedded memory solution has been realized with 0.276 μm<sup>2</sup> Local SONOS NVM cell, which has 20 μs program and 2 ms erase speed under 5.5 V bias condition, and good reliability without the special algorithms and cell array modifications.
    VLSI Technology, 2003. Digest of Technical Papers. 2003 Symposium on; 07/2003
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    ABSTRACT: This paper proposes a system for the extraction of typographical attributes, such as font style and typeface, that can be used to improve the performance of OCR and keyword spotting technologies on printed Korean document images. Three typographical features have been devised and experimented with 7,200 Korean word images. The individual accuracies for font style identification and typeface identification are 97.2% and 99.1%, respectively.
    Digital Libraries: Technology and Management of Indigenous Knowledge for Global Access, 6th International Conference on Asian Digital Libraries, ICADL 2003, Kuala Lumpur, Malaysia, December 8-12, 2003, Proceedings; 01/2003
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    ABSTRACT: This paper proposes a word segmentation method for machine-printed text lines. It utilizes gaps and special symbols as delimiters between words. A gap clustering technique is used to identify the gaps between words regardless of the gap-size variations among different document images. Next a special symbol detection technique is applied to find two types of special symbols lying between words. An experiment with 1,675 text lines in 100 different English and Korean documents shows that the proposed method achieves a high accuracy of word segmentation.
    Pattern Recognition, 2002. Proceedings. 16th International Conference on; 02/2002
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    Image Vision Comput. 01/2002; 20:25-35.
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    ABSTRACT: To remove temporal redundancy contained in a sequence of images, motion estimation techniques have been developed. However, the high computational complexity of the problem makes such techniques very difficult to be applied to high-resolution applications in a real time environment. If a priori knowledge about the motion of the current block is available before the motion estimation, a better starting point for the search of an optimal motion vector can be selected. In this paper, we present a new motion estimation approach based on temporal correlations of consecutive image frames that defines the search pattern and the location of initial search point adaptively. Experiments show that, comparing with DS (Diamond Search) algorithm, the proposed algorithm is about 0.1 ∼ 0.5(dB) better than DS in terms of PSNR and improves as much as 50% in terms of the average number of search points per motion estimation.
    EurAsia-ICT 2002: Information and Communication Technology, First EurAsian Conference, Shiraz, Iran, October 29-31, 2002, Proceedings; 01/2002
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    ABSTRACT: A gap-based method for the segmentation of handwritten Korean text lines into separate words is described. Three kinds of gap metrics have been evaluated, to see how much the gap information contributes to the task of handwritten Korean word segmentation
    Electronics Letters 08/2001; · 1.04 Impact Factor
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    ABSTRACT: We propose a word segmentation method for handwritten Korean text lines. It uses gap information to separate a text line into word units, where the gap is defined as a white-run obtained after a vertical projection of the line image. Each gap is classified into a between-word gap or a within-word gap using a clustering technique. We take up three gap metrics - the bounding box (BB), run-length/Euclidean (RLE) and convex hull (CH) distances - which are known to have superior performance in Roman-style word segmentation, and three clustering techniques - the average linkage method, the modified MAX method and sequential clustering. An experiment with 498 text-line images extracted from live mail pieces has shown that the best performance is obtained by the sequential clustering technique using all three gap metrics
    Document Analysis and Recognition, 2001. Proceedings. Sixth International Conference on; 02/2001
  • S H Kim, S H Jeong, H.K. Kwag
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    ABSTRACT: This paper proposes a new algorithm for texts/lines sepaxation in forms processing
    11/2000;

Publication Stats

490 Citations
32.83 Total Impact Points

Institutions

  • 2010
    • Kangwon National University
      • Department of Mechanical and Mechatronics Engineering
      Gangneung, Gangwon, South Korea
  • 2004–2006
    • Konkuk University
      • School of Physics
      Sŏul, Seoul, South Korea
  • 1999–2004
    • Chonnam National University
      • Department of Computer Science
      Gwangju, Gwangju, South Korea
  • 2001
    • Concordia University Montreal
      • Centre for Pattern Recognition and Machine Intelligence
      Montréal, Quebec, Canada