• Applied Microscopy
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• v.2 no.1
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• pp.39-46
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• 1972

There are many kinds of microscopes suitable for general studies; optical microscopes(OM), conventional transmission electron microscopes (TEM), and scanning electron microscopes(SEM). The optical microscopes and the conventional transmission electron microscopes are very familiar. The images of these microscopes are directly formed on an image plane with one or more image forming lenses. On the other hand, the image of the scanning electron microscope is formed on a fluorescent screen of a cathode ray tube using a scanning system similar to television technique. In this paper, the features and some applications of the scanning electron microscope will be discussed briefly. The recently available scanning electron microscope, combining a resolution of about $200{\AA}$ with great depth of field, is favorable when compared to the replica technique. It avoids the problem of specimen damage and the introduction of artifacts. In addition, it permits the examination of many samples that can not be replicated, and provides a broader range of information. The scanning electron microscope has found application in diverse fields of study including biology, chemistry, materials science, semiconductor technology, and many others. In scanning electron microscopy, the secondary electron method. the backscattererd electron method, and the electromotive force method are most widely used, and the transmitted electron method will become more useful. Change-over of magnification can be easily done by controlling the scanning width of the electron probe. It is possible. to continuously vary the magnification over the range from 100 times to 1.00,000 times without readjustment of focusing. Conclusion: With the development of a scanning. electron microscope, it is now possible to observe almost all-information produced through interactions between substances and electrons in the form of image. When the probe is properly focused on the specimen, changing magnification of specimen orientation does not require any change in focus. This is quite different from the conventional transmission electron microscope. It is worthwhile to note that the typical probe currents of $10^{-10}$ to $10^{-12}\;{\AA}$ are for below the $10^{-5}$ to $10^{-7}\;{\AA}$ of a conventional. transmission microscope. This reduces specimen contamination and specimen damage due to heatings. Outstanding features of the scanning electron microscope include the 'stereoscopic observation of a bulky or fiber specimen in high resolution' and 'observation of potential distribution and electromotive force in semiconductor devices'.

• The Journal of Korean Society for Radiation Therapy
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• v.14 no.1
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• pp.59-64
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• 2002

Purpose : In radiotherapy, various materials are used to located in treatment field unintentionally. It increases the dose delivered to the skin by interactions of the X-ray within the materials and occurs unwanted skin reaction.(due to the dose build-up effect) This aim of the this study is to measure the increase in skin dose when 13 materials are located in treatment field. Methods : Photon beam measurements were made using an plane-parallel chamber (Markus, PTW-Freiburg) in a polystyrene phantom. skin dose were measured using various overlaying 13 materials. a fixed geometry of a $10{\times}10cm$ field, a SSD=100cm and photon energy 4MV on Varian CLINAC 600C accelerator were used for all measurements. Results : There is an increase in skin dose for all materials($16.4{\sim}160.1\%$). As a percentage of maximum dose, the lowest skin dose were measured for the underwear with silk($43.2\%$) and the highest were measured for the 100m1 fluid-bag($96.6\%$) Conclusion : There is a significant increase in skin dose with 13 materials in the treatment field. a significant increase in skin dose can occur which could produce unwanted skin reaction. considerations for placement of 13 materials to be outside the treatment field whenever possible should be used to keep skin dose to a minimum level.

• Journal of Korean Dental Science
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• v.3 no.2
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• pp.4-11
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• 2010

Purpose: This study aimed at examining the thickness of lateral cortical bone in the mandibular posterior body and the location of the inferior alveolar nerve canal as well as investigating the clinically viable bone grafting site(s) and proper thickness of the bone grafts. Subjects and Methods: The study enrolled a total of 49 patients who visited the Department of Oral and Maxillofacial Surgery at Kyung Hee University Dental Hospital to have their lower third molar extracted and received cone beam computed tomography (CBCT) examinations. Their CBCT data were used for the study. The thickness of lateral cortical bone and the location of inferior alveolar nerve canal were each measured from the buccal midpoint of the patients' lower first molar to the mandibular ramus area in the occlusal plane of the molar area. Results: Except in the external oblique ridge and alveolar ridge, all measured areas exhibited the greatest cortical bone thickness near the lower second molar area and the smallest cortical bone thickness in the retromolar area. The inferior alveolar nerve canal was found to be located in the innermost site near the lower second molar area compared to other areas. In addition, the greatest thickness of the trabecular bone was found between the inferior alveolar nerve canal and the lateral cortical bone. Conclusions: In actual clinical settings involving bone harvesting in the posterior mandibular body, clinicians are advised to avoid locating the osteotomy line in the retromolar area to help protect the inferior alveolar nerve canal from damage. Harvesting the bone near the lower second molar area is judged to be the proper way of securing cortical bone with the greatest thickness.

• Earthquakes and Structures
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• v.24 no.1
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• pp.11-20
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• 2023

"Performance-based design (PBD)" is based on designing a structure with choosing a performance target under design criteria to increase the structure's resistance against earthquake effect. The plastic hinge formation is determined as one of the fundamental data in finite elements nonlinear analysis to distinguish the condition of the structure where more significant potential damage could occur. If the number of plastic hinges in the structure is increased, the total horizontal load capability of the structure is increased, also. Theoretically, when the number of plastic hinges of the plane frame structure reaches "the degree of hyperstaticity plus one", the structure will reach the capability of the largest ultimate horizontal load. As the number of plastic hinges to be formed in the structure increases towards the theoretical plastic hinge number (TPHN), the total horizontal load capability of the structure increases, proportionally. In the previous studies of the authors, the features of examining the new performance criteria were revealed and it was formulated as follows "Increase the total number of plastic hinges to be formed in the structure to the number of theoretical plastic hinges as much as possible and keep the structure below its targeted performance with related codes". With this new performance criterion, it has been shown that the total lateral load capability of the building is higher than the total lateral load capability obtained with the traditional PBD method by the FEMA 440 and FEMA 356 design guides. In this study, PBD analysis results of structures with frame carrier systems are presented in the light of the Turkey Building Earthquake Code 2019. As a result of this study, it has been shown that the load capability of the structure in the examples of structures with frame carrier system increases by using this new performance criterion presented, compared to the results of the examination with the traditional PBD method in TBEC 2019.

• Journal of Ocean Engineering and Technology
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• v.4 no.1
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• pp.88-100
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• 1990

Among the test methods to evaluate stress-corrosion cracking(SCC) on the basis of fracture mechanics, constant displacement(bolt) loading method using modified-WOL specimen is practically convenient. In this test method, compliance formula is generally required to calculate load(consequently $K_{ISCC}$). There are many problems in using the analytic compliance formula to calculate $K_{ISCC}$, so we had proposed the experimental $K_{ISCC}$ evaluation technique in the previous report. This study has employed the slightly altered configuration of modified-WOL specimen made of weldable structural stee(BS360-50D). With these specimens, stress-corrosion tests have been performed in $H_2S$ gas saturated 20% HCl solution. Through the test, the problems as mentioned earlier have been discussed again, and the proposed evaluation technique has been verified. And the stress-corrosion cracks and hydrogen blisters have been investigated in the initiation step with the aids of metallurgical micrographs, SEM fractographs, and EPMA analysis. The inclusions segregated in the mid-thickness region traps hydrogen to produce the hydrogen blistering. The applied or residual stress does not contribute the occurrence of the blister. Hydrogen absorbed into the mid-thickness region is consumed to produce the blistering so that stress-corrosion crack could hardly be detected at that region. The stress-corrosion cracks initiate from the inclusions and propagate in radial pattern. And the initiation site is remote from the crack tip and is inclined from the crack plane, which is assumed to be caused by the triaxial stress and the amount of the absorbed hydrogen.

• Journal of Conservation Science
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• v.5 no.2 s.6
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• pp.51-56
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• 1996

This paper deals with the restoration of ancient wooden bridge foundation which excavated in Seta river Shiga Prefecture, Japan. Shiga Archeological Research started a marine archeological investigation of the bridge foundation in 1987. The bridge foundation stricture excavated and have since then recovered about a lots of woods and another materials. The bridge foundation structure constructed log, timbers and stones. The species of those waterlogged wood were identified as two types, hardwood and softwood. Hardwood(log : Cyclobalanopsis) was used for below foundation and softwood (timber' Chamaecyparis obtusa Endl. Cupreessaceae) was used for base structure. One of those timber sample dated by dendrochronology, we asked Dr. Misutani*. The softwood gave a felling date of 567 A.D. In result, the ancient Seta bridge foundation structure had constructed between Asuka and Nara period. We healed the news that ancient bridge foundation excavated at Woljyongyo site in Kyongju, Korea 1987. The bridge foundation Setakarahashi is similar in plane and structure to Woljyongyo structures. The Woljyongyo site report had be of value for reference. We had planning to restore those woods. Hardwood log was got serious damage. The water content varies from 400 to $600\%$. The other timbers water content varies about $200\%$. In the Shiga Center for Archaeological Operations and the Azuchi Castle Archaeological Museum, we set up the PEG impregnation tank. Those wooden objects treated by PEG method. PEG with a molecular weight of 4000. The treatment results may be considered satisfactory. The ancient wooden Seta bridge was reconstructed in Biwako Museum which established in Oct. 1996. We must take care of indoor exhibition environments. (*Nara National Cultual Properties Research Institute).

• Journal of the Korean Institute of Rural Architecture
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• v.24 no.2
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• pp.13-20
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• 2022

In this study, a general low-rise building was selected to compare the new shear wall reinforcement method, which is a general method among the existing reinforcement methods, and the reinforcement method using sinusoidal corrugated web reinforcement. And it was confirmed that the following effects can be expected. Sinusoidal corrugated web members can be carried out in a short period of time as it does not require the removal of the masonry filling wall, the reinforcement of reinforcing bars, and the curing period of the concrete. It is effective in preventing damage that may occur when masonry filling wall is overturned in the out-of-plane direction, and the burden of the foundation is also reduced, and thus the construction period and cost required for reinforcement can greatly be reduced. By adjusting the number of sinusoidal corrugated web member, details of joints, and reinforcement positions, the flow of load can be induced to have an advantageous effect on the building. It can be considered as the most suitable reinforcement plan in terms of life safety. Unlike the shear wall that fills between the columns, the sinusoidal corrugated web members, which has a width of 1.5m, can install openings between two columns depending on the purpose of use, and can be expected to have a great effect in terms of usability due to its free installation location. As mentioned above, the seismic reinforcement using a sinusoidal corrugated web members, can expect great effect compared to conventional reinforcement methods in terms of usability, economic feasibility, and stability.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.579-587
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• 1998

In this study, fatigue behavior of the optical fiber sensor embedded in composite laminate was investigated. Static tensile and fatigue tests were performed for three types of laminated composite specimens with embedded optical fiber sensor in the neutral plane ; [0/sub 6//OF/0/sub 6/]/sub T/, [0/sub 2//90/sub 4//OF/90/sub 4//0/sub 2/]/sub T/ and [0/sub 3//90/sub 3//OF/90/sub 3//0/sub 3/]/sub T/. The fracture of the embedded optical fiber sensor was detected by the intensity drop off of laser signal transmitted through the optical fiber sensors embedded within laminated composite specimen. The maximum fatigue stress applied to laminated specimen was compared with the average tensile stress at which the fracture of the embedded optical fiber within the laminate occurred under static tensile loading. From the experiments, firstly it is observed that the decrease in the life of optical fiber sensors embedded within unidirectional-ply laminate by the fatigue loading is relatively small compared to that of cross-ply laminate. Secondly, the optical fiber embedded in unidirectional-ply laminate is fractured by the fatigue damage due to the growth of internal defects of optical fiber, however the optical fiber embedded in cross-ply laminate is fractured by the growth of transverse matrix crack.

• Archives of Reconstructive Microsurgery
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• v.5 no.1
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• pp.106-111
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• 1996

Purpose : Propose a surgical technique in donor harvesting method in free vascularized proximal fibular epiphysis. Methodology : Concerned about growth potentials of the transplanted epiphysis in our long term results of the epiphyseal transplanted 13 cases more than 4 years follow-up, anterior tibial artery which contains anterior tibial recurrent artery is most reliable vessel to proximal fibular epiphysis which is the best donor of the free vascularized epiphyseal transplantation. In vascular anatomical aspect proximal fibular epiphysis norished by latearl inferior genicular artery from popliteal, posterior tibial recurrent artery and anterior tibial recurrent artery from anterior tibial artery and peroneal artery through metaphysis. The lateral inferior genicular artery is very small and difficult to isolate, peroneal artery from metaphysis through epiphyseal plate can not give enough blood supply to epiphysis itself. The anterior tibial artery which include anterior tibial recurrent and posterior tibial recurrent artery is the best choice in this procedure. But anterior tibial recurrent artery merge from within one inch from bifucating point of the anterior and posterior tibial arteries from popliteal artery. So it is very difficult to get enough vascular pedicle length to anastomose in recipient vessel without vein graft even harvested from bifucating point from popliteal artery. Authors took recipient artery from distal direction of anterior tibial artery after ligation of the proximal popliteal side vessel, which can get unlimited pedicle length and safer dissection of the harvesting proximal fibular epiphysis. Results : This harvesting procedure can performed supine position, direct anterolateral approach to proximal tibiofibular joint. Dissect and isolate the biceps muscle insertion from fibular head, micro-dissection is needed to identify the anterior tibial recurrent arteries to proximal epiphysis, soft tissue release down to distal and deeper plane to find main anterior tibial artery which overlying on interosseous membrane. Special care is needed to protect peroneal nerve damage which across the surgical field. Conclusions : Proximal fibular epiphyseal transplantation with distally directed anterior tibial artery harvesting technique is effective and easier dissect and versatile application with much longer arterial pedicle.

• Journal of the Korean Professional Engineers Association
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• v.17 no.3
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• pp.6-21
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• 1984

A rock slide in amount of 100 tons in weight happened at 7: 10 a.m., 4th October 1982, on the southwestern ridge of Mt. Seunghag, Busan City. The original rock mass of the rock slide is located 850m west from the Dangri Crushed Stone Quarry. The geology of the area consists of agglomerate, andesite, andesitic tuff, and shale hornfels of the Cretaceous Yucheon Group. The rock blocks were first shifted along the steep joint plane on an andesite outcrop at the site and then to the eastern foot of the mountain slope where some private houses are placed. The mountain slope is covered with thick superficial soil. A slided monolithic-block with 83 tons in weight from the rock slide met with an accident of striking against a house with a tremendous force, to which much damage was done as much as its half was destroyed. The rock-slided block pierced the board-floored room only posited at the center and by the bedroom of the house making a pass like a bullet hole, and hence cut a big pine tree with 24 centimeters in diameter at a distance of 26 meters down the house. However nobody was killed or injured in the stricken house, though seven family members were stayed therein at the very time of accident. They really met a rare opportunity in an unhappy disaster. Measurements of the rock slide were made in the course of the field survey. The monolithic mass was transported by way of saltation, rolling, and sliding to a distance of 300 meters down along the slope dipping 30$^{\circ}$ east. It took about 16 seconds front tile outcrop to the terminal. The acceleration value of the monolithic rock slide is 2.35m/sec$^2$.