방사선사진의 인덱스-순서 분석을 통한 치아경조직의 탈염화 검출

박동현,박영호,김경숙,박정훈,이기자,최삼진,최용석,황의환,박헌국 대한구강악안면방사선학회 2009 Imaging Science in Dentistry Vol.39 No.2

Purpose : The purpose of this study was to develop the radiographic technique for detecting the demineralization which is known as indication of dental caries. Materials and Methods : This technique was based on the comparing of multiple radiographs which was irradiated by multiple X-ray spectra. For the meaningful comparing, the multiple radiographs were reconstructed to the dosimetrically consistent images using a standard material. The difference of resulting images of same target with multiple spectra represents the difference of response of material as regards the spectra. Results : We have found about 10% of demineralization of dental hard tissues particularly in the proximal region through the analyzing of differences. Conclusion : Most intriguing thing in this investigation was that the method to analyze difference shows us to an anatomic structure of dental hard tissues even if absolute values of optical density were excluded during the procedures.

Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

전문 마라톤화용 기능성 개발을 위한 운동역학적 연구(Ⅰ)

박승범,서국웅,김용재 한국운동역학회 2001 한국운동역학회지 Vol.11 No.3

Various approaches can be used to study a special field such as biomechanical aspects of marathon shoes. A runner who wants to buy a pair of running shoes is confronted with a wide range of models, ranging from inexpensive to expensive, from soft to hard, and from red to yellow. These marathon shoes may have special features like wedges or exchangeable damping elements which visually underline the special quality of the shoes. Advertisements for running shoes in marathoner's magazines explain their products by using words such as "support", "rearfoot control", "cushioning", "shock distributor" and "heel stabilizer". One aspect of marathon shoes biomechanical design is the protection and /or the reduction of injuries. In other words, it is aspect of forces acting on the human body, and also the effects these forces produce in this system. The problems can be studied using theoretical techniques using mathematical models and some of these are discussed int below. A marathon shoe must fit not only overall length and ball width, but with respect to several other aspects such as the instep, arch, top lines, and heel and toe curve. A marathon shoes must fit your biomechanical needs very, very well. Match the support in the shoe as closely as possible to your pronation factor, or how much motion your feet experience when on the ground. Marathon shoes must fit your feet even better than the proverbial glove. They swell from the ramped-up circulation that accompanies continuous activity, and may actually spread out a bit as the 26 bones and dozens of tendons, ligaments and muscles in each foot adapt to several hours of pounding. Marathon shoes should be racing flats only if you think you can win. What makes no sense is to think that is significant when compared with how hard your shoes have to work during the last few miles to support your rapidly fading body. Lightweight shoes mean lightweight support. A large variety of elements which have various names, such as inserts, arch supports, arch cookies, orthotics, and orthoses, can be put into a shoes. The inserts for the sports shoe market consist of many different types of plastics and E.V.A(Ethylene Vinyl Acetate). Another type of insert is the built-in insert which is incorporated into or onto the sole of the shoe. This is a rather rare form of conventional shoe construction. Changes in midsole geometry and material are only one of various strategies which can be used to alter the properties of a running shoe. Heel counters, heel stabilizers, insoles, inserts, additional wedges, and different lasts are some additional strategies used in running shoe construction. Many of them are used in combination with others which may introduce additional problems in quantifying their effects. An athlete can use external elements to influence load and stress on his body. The two most important ones are the running shoe and the surface. On the other hand, he or she can use internal elements which anre muscles, tendons, ligaments, and so forth, and his or her running style. Careful exercise and control of these elements is an important factor in the attempt to reduce running injuries.

천연제올라이트를 지지체로 사용한 고온건식 아연계 탈황제의 반응특성 연구

박노국,정용길,이종대,이태진,김재창 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.5

고온건식 탈황제의 지지체로 알루미나와 천연제올라이트를 사용하여 아연계 탈황제를 제조하였으며 성능을 조사하였다. 두 가지 탈황제의 반응특성실험은 480℃/580℃(황화/재생온도)에서 칸 밸런스와 고정층 반응장치로 반응속도와 황수용능력을 비교하였으며 내마모 실험장치를 이용하여 탈황제의 내마모도를 조사하였다. 두 탈황제의 성능 실험결과 천연제올라이트를 지지체로 사용한 탈황제의 초기 황화반응속도가 알루미나를 지지체로 사용한 탈황제보다 빨라졌으며, 10 cycle에서 황수용능력이 20 gS/100 g sorbent 이상 유지되었다. 내마모성은 AI(마모지표)값이 14.7%정도였다. 본 연구에서는 천연제올라이트의 고온건식 탈황제의 지지체로 적용 가능성을 확인하였다. Two types of zinc-based sorbents using alumina and natural zeolite as the supports for hot-gas desulfurization were prepared, and investigated their desulfurization capability. Their reaction rate and sulfur capacity were compared by Cahn balance and over the fixed bed reactor system at 480℃/580℃ (sulfidation/regeneration). The attrition resistance was measured by ASTM methd. Thc initial sulfidation rate of ZnO/natural zeolite sorbent was higher than that of ZnO/alumina, and the sulfur capacity of ZnO/natural zeolite sorbent was maintained above 20 gS/l00 g sorbent for 10 cycles. A attrition index was 14.7%. The use of natural zeolite as a support of sorbents may be possible for hot gas desulfurization.

위삼차신경핵에서 일차구심성 신경섬유 종말부의 미세구조 및 연접양상

배용철,박국필,정경원,박매자,조희중 대한해부학회 1995 Anatomy & Cell Biology Vol.28 No.5

인공 치아우식 발생 모델에서 디지털 방사선 공제술을 이용한 인접면 치아우식증의 진단

박정훈,최용석,황의환,이기자,최삼진,박영호,김경숙,진현석,홍경원,오범석,박헌국 대한구강악안면방사선학회 2009 Imaging Science in Dentistry Vol.39 No.1

Purpose : The purpose of the experiment was to evaluating the diagnostic ability of dental caries detection using digital subtraction in the artificial caries activity model. Materials and Methods : Digital radiographies of five teeth with 8 proximal surfaces were obtained by CCD sensor (Kodak RVG 6100 using a size #2). The digital radiographic images and subtraction images from artificial proximal caries were examined and interpreted. In this study, we proposed novel caries detection method which could diagnose the dental proximal caries from single digital radiographic image. Results : In artificial caries activity model, the range of lesional depth was 572-1,374 μm and the range of lesional area was 36.95-138.52mm². The lesional depth and the area were significantly increased with demineralization time (p<0.001). Furthermore, the proximal caries detection using digital subtraction radiography showed high detection rate compared to the proximal caries examination using simple digital radiograph. Conclusion : The results demonstrated that the digital subtraction radiography from single radiographic image of artificial caries was highly efficient in the detection of dental caries compared to the data from simple digital radiograph.

八會血 應用의 經穴學的 硏究

金容佑,朴寅圭,林鍾國 圓光大學校 韓醫學硏究所 1992 원광한의학 Vol.2 No.1

Shu(수) point is the communication channel of meridian-viscera and body surface. It is used for the point acupuncture and moxibustion that the solid and hollow organs and meridians are closely related with each other. Also, that is point where the channel energy(脈氣) of meridian and viscera organs communicate inward and outward. Hence, the knowledge on the meridian and its points are essential for acupunture and moxibustion therapy. Especially, Palhoae point(八會穴) is one of the special points chiefly used for the remedy of faver. In this study, the use of Palhoae point(八會穴) is examined through the literatural survey.

고온 석탄 가스정제를 위한 아연계 탈황제의 첨가제 영향

정용길,이종대,박노국,이태진 한국공업화학회 2003 응용화학 Vol.7 No.1

The effect of additives on zin-base desulfurization sorbents for hot coal gas clean-up at middle temperature was studied in this work. In roder to advance a regeneration and durability of ZnO/natural zeolite sorbents, it modification by adding Fe_2O_3 or ZrO_2 was studied. It were prepared that the ZnO/natural zeolite/Fe_2O_3 or ZrO_2 by physical mixture method : the amount of ZnO, natural zeolite and additives were repectively fixed as a wight percent of 65, 25 and 10. The reactivity of sorbents was determined for 5cycles of sulfidation and regeneration in fixed-bed. Result showed that regeneration and durability were improved. Further more, the sorbent, containing ZrO_2, an excellent attrition resistance. As mentioned above, the sorbents, were highly advanced for durability, regeneration and attrition resistance by additive.

여성 요실금에서 Kontinence™와 Compact Elite™의 치료효과 비교

양상국,정상원,오미희,노용수,김홍섭,우응제,박승훈,이수열 건국대학교 의과학연구소 1999 건국의과학학술지 Vol.9 No.-

Biofeedback and pelvic floor electrical stimulation are new modalities that have been advocated for the treatment of female urinary incontinence. The aim of this study was to compare prospectively the therapeutic effect of Kontinence™(HMT Co., Korea) with Compact Elite™(ECL Co., France) in female urinary incontinence. All patients were evaluated with a complete history, physical examination, urinalysis, urine culture and urodynamic study. Eighteen patients were treated with Compact Elite™, and thirteen patients with Kontinence™. Enrolled patients had completed 8 office sessions consisting of biofeedback and intravaginal electrical stimulation according to the program of each machines. Overall treatment response was graded by patients on a scale of complete cure to aggravation. At two weeks after last session, overall improvement rate was 78% in Compact Elite™group and 92% in Kontinence™group(p>0.05). Overall patients' acceptability during treatment course was greater than 80% in both machines(p>0.05). There were no unexpected clinical findings during Kontinence™ treatment. After Kontinence™treatment, there were no laboratory changes including electrocardiography, complete blood count, liver function profile, and chest PA. These results showed that the biofeedback and electrical stimulation with Kontinence™was safe and moderately effective for female urinary incontinence comparable to Compact Elite™. However, long-term results of a larger patients are needed to ensure the therapeutic effect of Kontinence™.

STS304와 S15C 이종마찰압접부의 접합계면 응력해석

오정국,차용훈,성백섭,박창언,김하식,김충환 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.3

Friction welding has many merits such as energy efficiency, simple processing, etc. but it is difficult to obtain good welding at the welded interfaces and heat affected zone. It is discovered that stress singularity exists at the interfaces and heat affected zone. The computer program based on boundary element method is utilized in this study. A mathematical model is implemented based on results from several experiments performed at and around the welded interfaces and heat affected zone of disimilar metal under static and dynamic loadings. This study is to investigate the characteristics of the deformation and fracture behavior around interfaces for friction welded materials under static tensile load. Also, the stress distribution at the tip of crack is analyzed by using BEM based on Kelvin's solution of 2-dimensional binding zone. The results of BEM are identical with those in case of considering interfaces of both heat affected zone. Also, stress singularity at the tip of interfaces appears when the elastic modulus ration is 1.07.