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A Study on the Establishment of Basic Design Concept for Semi-Submersibles (해저자원(海底資源) 개발용(開發用) Semi-Submersible 설계기준(設計基準)의 정립(定立)을 위한 연구(硏究))

  • J.E.,Park;Z.G.,Kim;J.H.,Hwang;S.J.,Yim;H.S.,Choi
    • Bulletin of the Society of Naval Architects of Korea
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    • v.20 no.2
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    • pp.1-20
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    • 1983
  • In this paper design criteria for semi-submersibles, effective at the stage of basic design, are reviewed first generally. Thereafter an extensive study is focussed on essential problematic areas such as design load, heaving motion, overall structural analysis and welding technique. The necessity for this kind of research is apparent in the light of the fact that ocean exploration and exploitation becomes extended to deeper ocean and that semi-submersibles are the most favorite unit for operation under this environment. In some sense principles in naval architecture are indeed applicable to the design of semi-submersible. However, because of the difference in geometry between ships and semi-submersibles, there are significant deviations in design method. A thorough discussion is made on particular behaviours of a semi-submersible in stability, wave load, motion characteristics and structural responses. Then some calculation-procedures and design guidelines are tentatively proposed. A numerical calculation for a semi-submersible Sedco 708 is exemplified for better understanding of the concept. The structure has 4 main and another 4 secondary stabilizing columns with catamaran-type lower hull. In this example design condition is supposed to be 28m wave height, 90 knots wind speed for survival condition and seastate 6 for operational condition in water of 100m depth. The numerical result implies that the actual design of this model can be assessed close to optimum. Further intensive research is strongly required in the subject fields of dynamic stability, rational evaluation of wave load statistical basis for fatigue life judgement.

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TEMPERATURE CHANGES IN THE PULP ACCORDING TO VARIOUS ESTHETIC RESTORATIVE MATERIALS AND BASES DURING CURING PROCEDURE (광중합 시 수종의 심미적 수복재와 이장재의 사용에 따른 치수내 온도변화)

  • 장혜란;이형일;이광원;이세준
    • Restorative Dentistry and Endodontics
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    • v.26 no.5
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    • pp.393-398
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    • 2001
  • Polymerization of light-activated restorations results in temperature increase caused by both the exothermic reaction process and the energy absorbed during irradiation. Within composite resin, temperature increases up to 2$0^{\circ}C$ or more during polymerization. But, insulation of hard tissue of tooth lowers this temperature increase in pulp. However, many clinicians are concerned about intrapulpal temperature injury. The purpose of this study was to evaluate temperature changes in the pulp according to various restorative materials and bases during curing procedure. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece fissure bur. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn below restorative materials for evaluating of temperature changes. This thermocouple was connected to temperature-recording device(Multiplication analyzer MX, 6.000, JAPAN). Temperature changes was evaluated from initial 37.$0^{\circ}C$ after temperature changes to 37.$0^{\circ}C$. Tip of curing unit was placed in the center of prepared cavity separated 1mm from restorative materials. Curing time was 40s. The restorative materials were used with Z 100, Fuji II LC, Compoglass flow and bases were used with Vitrebond, Dycal. Resrorative materials were placed in 2mm. The depth of bases were formed in 1mm and in this upper portion, resin of 2mm depth was placed. This procedure was performed 10 times. The results were as follows. 1. All the groups showed that the temperature in pulp increased as curing time increased 2. The temperature increase of glass ionomer was significantly higher than that of Resin and Compomer during curing procedure (P<0.05). 3. The temperature increase in glass ionomer base was significantly higher than that of Calcium hydroxide base during Resin curing procedure (P<0.05).

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INFLUENCE OF ARTIFICIAL SALIVA CONTAMINATION ON BONDING OF DENTIN ADHESIVES TO DENTIN (인공타액 오염이 수종 상아질접착제와 상아질간의 결합에 미치는 영향)

  • Ryu, Mee-Ae;Yang, Kyu-Ho;Oh, Won-Mann
    • Restorative Dentistry and Endodontics
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    • v.17 no.2
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    • pp.383-397
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    • 1992
  • The purpose of this study was to evaluate the influence of artificial saliva contamination on bonding of several dentin adhesives to dentin. Sixty - three human molar teeth extracted within a month were used. Each tooth was sectioned longitudinally in a buccolingual direction to obtain 126 specimens. These specimens were randomly divided into three groups and were treated by Scotchbond 2, Gluma and All bond. Each group was subdivided into three subgroups; normal group not contaminated with artificial saliva, contaminated with artificial saliva and dried group, and contaminated with artificial saliva and washed and dried group. Enamel/dentin bonding agent(Dental Adhesive of Scotchbond 2) was applied and light cured on the treated dentin surfaces. Thereafter P - 50 were cured on them, and specimens were stored in $37^{\circ}C$ artificial saliva for 24 hours before measuring shear bond strength. Shear bond strengths were determined using an universal testing machine with cross head speed 1mm/min and SEM examinations were conducted to evaluate the resin - dentin interface and degree of penetrating resin string into the dentinal tubules. The following results were obtained. 1. Normal groups not contaminated with artificial saliva showed greater shear bond strength than any other group contaminated with artificial saliva(P<0.01). 2. The shear bond strengths showed no significant difference between washed groups with distilled water and not washed groups after contamination with artificial saliva(P>0.05). 3. In normal groups, the shear bond strength of A group was significantly greater than in any other group(P<0.01). 4. In Sand G groups, fractures after shear bond strength tests occured adhesively on resintooth interface in all specimens. But in A groups, fracture of the normal group occured cohesively in dentin and fracture of the contaminated groups occured adhesively and cohesively. 5. On SEM examination, the number of resin strings penetrated into dentinal tubules were the greatest in normal groups, followed by, in descending order, washed groups and not washed groups after contamination with artificial saliva.

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Fabrication of Nano Dot and Line Arrays Using NSOM Lithography

  • Kwon Sangjin;Kim Pilgyu;Jeong Sungho;Chang Wonseok;Chun Chaemin;Kim Dong-Yu
    • Journal of the Optical Society of Korea
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    • v.9 no.1
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    • pp.16-21
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    • 2005
  • Using a cantilever type nanoprobe having a 100㎚m aperture at the apex of the pyramidal tip of a near-field scanning optical microscope (NSOM), nanopatterning of polymer films are conducted. Two different types of polymer, namely a positive photoresist (DPR-i5500) and an azopolymer (Poly disperse orange-3), spincoated on a silicon wafer are used as the substrate. A He-Cd laser with a wavelength of 442㎚ is employed as the illumination source. The optical near-field produced at the tip of the nanoprobe induces a photochemical reaction on the irradiated region, leading to the fabrication of nanostructures below the diffraction limit of the laser light. By controlling the process parameters properly, nanopatterns as small as 100㎚ are produced on both the photoresist and azopolymer samples. The shape and size variations of the nanopatterns are examined with respect to the key process parameters such as laser beam power, irradiation time or scanning speed of the probe, operation modes of the NSOM (DC and AC modes), etc. The characteristic features during the fabrication of ordered structures such as dot or line arrays using NSOM lithography are investigated. Not only the direct writing of nano array structures on the polymer films but also the fabrication of NSOM-written patterns on the silicon substrate were investigated by introducing a passivation layer over the silicon surface. Possible application of thereby developed NSOM lithography technology to the fabrication of data storage is discussed.

Tip Deflection Analysis of Mobile Habor Crane Supported by Cable and Elastic Bar (케이블과 탄성보로 지지되는 모바일 하버 크레인의 끝단 처짐량 분석)

  • Hwang, Soon-Wook;Han, Ki-Chul;Choi, Eun-Ho;Cho, Jin-Rae;Lim, O-Kaung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.3
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    • pp.283-288
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    • 2010
  • Mobile harbor is characterized by the lightweight compact structure when compared to the conventional above-ground port container crane. A new concept RORI crane system, which was devised for mobile harbor to satisfy the compactness and light weightness, not only can load/unload containers with high speed on sea but can be completely folded at maneuvering mode. This study is concerned with the tip deflection of the horizontal boom of mobile harbor at container loading operation. Both the theoretical method utilizing the Castigliano's theorem and the numerical approach by finite element method are employed, and the reliability of the latter approach is verified through the comparison with the theoretical results. And then, the effect of the initial cable tension on the tip deflection is parametrically examined by the finite element analysis.

Parallel Processing Method for Generating Elemental Images from Hexagonal Lens Array (육각형 렌즈 어레이로부터 요소영상을 생성하기 위한 병렬 처리 기법)

  • Kim, Do-Hyeong;Park, Chan;Jung, Ji-Sung;Kwon, Ki-Chul;Kim, Nam;Yoo, Kwan-Hee
    • The Journal of the Korea Contents Association
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    • v.12 no.6
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    • pp.1-8
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    • 2012
  • According that most integral imaging techniques have used rectangular lens array, this integrated distribution of light is recorded in the form of a rectangular grid. However, hexagonal lens array gives a more accurate approximation of ideal circular lens and provides higher pickup/display density than rectangular lens array[4]. Using the parallel processing technique in order to generate the elemental imaging for hexagonal lens array, each pixel that compose the elemental imaging should be determined to belong to the hexagonal lens. This process is output to the screen for every pixel in progress, and many computations are required. In this paper, we have proposed parallel processing method using an OpenCL to generate the elemental imaging for hexagonal lens array in 3D volume date. In the experimental result of proposed method show speed of 20~60 fps for hexagonal lens array of $20{\times}20$ sizes and input data of Male[$128{\times}256{\times}256$] volume data.

A STUDY ON THE RESIN IMPREGNATION AND SHEAR BOND STRENGTH BY VARIOUS DENTIN CONDITIONERS (수종 상아질 표면처리제에 의한 레진 침투 및 전단결합강도에 관한 연구)

  • Lee, Kwang-Won;Lee, Myung-Jong
    • Restorative Dentistry and Endodontics
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    • v.15 no.1
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    • pp.201-216
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    • 1990
  • A variety of surface pre-treatments have been advocated to prepare the dentin prior to placement of a bonding agent. The purpose of this study was to evaluate the effect of various dentin conditioners upon the degree of resin impregnation to the dentinal tubules and the shear bond strength of a new dentinal bonding agent (Scotchbond 2) used in conjunction with a visible light cured composite (Silux). The healthy eighty human molars extracted due to periodontal or orthodontic reasons were used and randomly divided into five groups. All the grinded dentin surfaces were conditioned with 3% $H_2O_2$, Cavity Cleanser (Columbus/Bayer), Dentin Conditioner (GC Inter. Corp.), Scotchprep (3M Co.) according to the manufacturer's directions. The specimens were then demineralized in 10% HCl for 20 sec. and 24 hrs. in order to observe the resin tags in Hitachi X-450 scanning electron microscope at 25KV. Also, shear strengths were obtained using an Instron Testing Machine with a cross head speed of 1 mm/min. The following results were obtained ; 1. In group treating with Dentin Conditioner and Scotchprep, the resin strings were formed on most of the surfaces and penetrated more than $50{\mu}m$ into the tubules. 2. The inner surface of resin treated with Cavity Cleanser, indicating the resin strings formed partly and penetrated about in depth of $30{\mu}m$. 3. In control and experimental group treated with 3% $H_2O_2$, the resin tags were not formed, if any, penetrated shortly. 4. Shear bond strengths in groups treating with Dentin Conditioner and Scotchprep were statistically significant increase than with 3% $H_2O_2$. (P<0.01). 5. The Scotchprep treatment group was significantly higher in shear strength than groups treated with no conditioning and Cavity Cleanser.(P<0.01) 6. Shear bond strengths evaluated were gradually increase in proportion to the tag length of resin impregnation.

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A Process Model for the Systematic Development of Safety-Critical Systems (안전중시 시스템을 위한 체계적인 설계 프로세스에 관한 연구)

  • Yoon, Jae-Han;Lee, Jae-Chon
    • Journal of the Korea Safety Management & Science
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    • v.11 no.3
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    • pp.19-26
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    • 2009
  • It is becoming more and more important to develop safety-critical systems with special attention. Examples of the safety-critical systems include the mass transportation systems such as high speed trains, airplanes, ships and so forth. Safety critical issues can also exist in the development of atomic power plants that are attracting a great deal of attention recently as oil prices are sky-rocketing. Note that the safety-critical systems are in general large-scale and very complex for which case the effects of adopting the systems engineering (SE) approach has been quite phenomenal. Furthermore, safety-critical requirements should necessarily be realized in the design phase and be effectively maintained thereafter. In light of these comments, we have considered our approach to developing safety-critical systems to be based on the method combining the systems engineering and safety management processes. To do so, we have developed a design environment by constructing a whole life cycle model in two steps. In the first step, the integrated process model was developed by integrating the SE (ISO/IEC 15283) and systems safety (e.g., hazard analysis) activities and implemented in a computer-aided SE tool environment. The model was represented by three hierarchical levels: the life-cycle level, the process level, and the activity level. As a result, one can see from the model when and how the required SE and safety processes have to be carried out concurrently and iterately. Finally, the design environment was verified by the computer simulation.

Objective evaluation of the color of tongue substance using L*a*b* color coordinates

  • Park, Young-Jae;Park, Young-Bae
    • Advances in Traditional Medicine
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    • v.6 no.2
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    • pp.112-120
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    • 2006
  • The purpose of this study was to analyze whether quantitative evaluation of the color of the tongue substance using $L^*a^*b^*$ color coordinates system could minimize the problems arising from the different illuminating conditions or not. In controlled 4 different illuminating conditions (by natural light, flashlight, f-number, shutter speed),12 healthy subjects were photographed of their tongue substance through a digital camera (C-2100uz, Olympus Co.), both on the top surface and on the bottom surface of the tongue substance by two examiners, twice at 3 day intervals. Clinician evaluation was also performed grading the redness of the tongue substance in the form of 5-points scale by 6 clinicians. As a result, there was no significant difference in color differences between the color of the tongue substance and the reference red card in the 4 different illuminating conditions. Intra-rater reliability was satisfied and even though limitedly, inter-rater reliability was satisfied. Color differences were significantly correlated with the results by the clinicians, although they were applicable limitedly to specific illuminating conditions. Our results indicate that the application of the color differences in tongue diagnosis could not only evaluate the color information quantitatively, but also minimize the problems arising from the different illuminating conditions and that there was the significant difference in the visual evaluation of the red color of the tongue substance, both between the clinicians and between the illuminating conditions.

The Study of Optical Device embedded Optical Alignment fabricated by Roll to Roll Process (롤투롤 공정을 이용한 광정렬 구조 내장형 광소자 연구)

  • Jo, Sang-Uk;Kang, Ho-Ju;Jeong, Myung-Yung
    • Journal of the Microelectronics and Packaging Society
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    • v.20 no.3
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    • pp.19-22
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    • 2013
  • Recently, high speed transmission and large information demand have been increased. Also, researches of integrated optical device for large production and high-efficient planar lightwave circuit (PLC) have been increased. In this paper, integrated optical alignment is proposed which makes passive alignment between optical device and optical fiber possible. The integrated optical device consists of splitter structures which have one input and two outputs. The proposed integrated structure was fabricated by roll-to-roll (RTR) processing method. This method enables to manufacture continuously and the processing time can be shortened. Optical property of the fabricated optical device showed 3.9 dB insertion loss and 0.2 dB optical uniformity using the light source with 1550 nm wavelength.