• 제목/요약/키워드: 회전 제거력

검색결과 59건 처리시간 0.021초

Effect of cutting flute length and shape on insertion and removal torque of orthodontic mini-implants (교점용 미니 임플랜트의 cutting flute의 길이 및 형태에 따른 식립 및 제거 토크의 비교)

  • Yun, Soon-Dong;Lim, Sung-Hoon
    • The korean journal of orthodontics
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    • 제39권2호
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    • pp.95-104
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    • 2009
  • Objective: The purpose of this study was to evaluate the effect of length and shape of cutting flute on mechanical properties of orthodontic mini-implants. Methods: Three types of mini-implants with different flute patterns (Type A with 2.6 mm long flute, Type B with 3.9 mm long and straight flute, Type C with 3.9 mm long and helical flute) were inserted into the biomechanical test blocks (Sawbones Inc., USA) with 2 mm and 4 mm cortical bone thicknesses to test insertion and removal torque. Results: In 4 mm cortical bone thickness, Type C mini-implants showed highest maximum insertion torque, then Type A and Type B in order. Type C also showed shortest total insertion time and highest maximum removal torque, but Type A and B didn't showed statistically significant difference in insertion time and removal torque. In 2 mm cortical bone thickness, there were no significant difference in total insertion time and maximum removal torque in three types of mini-implants, but maximum insertion torque of Type A was higher than two other Types of mini-implants. Conclusions: Consideration about length and shape of cutting flute of mini-implant is also required when the placement site has thick cortical bone.

Development of a Rotation Swab Pig Method for Cleaning Water Pipes (상수관의 세척을 위한 회전식 스왑피그 공법 개발)

  • Kicheol Lee;Jaeho Kim;Kisung Kim;Jeongjun Park
    • Journal of the Korean Geosynthetics Society
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    • 제23권2호
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    • pp.63-75
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    • 2024
  • Drinking water is an essential element to ensure the basic human right to live, and the quality of clean water must always be ensured. However, domestic water facilities, which were installed intensively in the early 2000s, are deteriorating. The accidents such as discoloration of water such as chromaticity and turbidity as well as leakage of substances frequently occur. However, since it is virtually impossible to replace all water pipes, the detailed standards for maintenance of water pipe network facilities established in 2021 require water pipe cleaning. The swab pig method, one of the water pipe cleaning methods, is a method of physically removing substances in pipes and is evaluated as having the highest cleaning efficiency. However, Swab is highly likely to be damaged or deformed during the cleaning process, and may even be lost. Therefore, in this study, the material of the pig was changed to a material with high compressibility, and it was made as close as possible to the inner wall of the water pipe. And, to maximize cleaning efficiency, a rotation swab pig with a rotation blade was developed. In addition, high-strength wire and winding equipment were additionally developed to eliminate the possibility of loss and to determine the location of the pig. The inlet and outlet are connected with wires, and after verifying the performance of each detailed technology, the technology was applied on a test bed with a 30m section. As a result of the application, the performance of the technology was verified by measuring the process time and evaluating applicability.

Measuring Intracellular Mycobacterial Killing Using a Human Whole Blood Assay (인체 전혈 모델을 이용한 세포내 결핵균 살균력에 관한 연구)

  • Cheon, Seon-Hee;Song, Ho-Yeon;Lee, Eun-Hee;Oh, Hee-Jung;Kang, In-Sook;Cho, Ji-Yoon;Hong, Young-Sun
    • Tuberculosis and Respiratory Diseases
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    • 제53권5호
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    • pp.497-509
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    • 2002
  • Background : The mechanisms through which cellular activation results in intracellular mycobacterial killing is only partially understood. However, in vitro studies of human immunity to Mycobacterium tuberculosis have been largely modeled on the work reported by Crowle, which is complicated by several factors. The whole blood culture is simple and allows the simultaneous analysis of the relationship between bacterial killing and the effect of effector cells and humoral factors. In this study, we attempted to determine the extent to which M. tuberculosis is killed in a human whole blood culture and to explore the role of the host and microbial factor in this process. Methods : The PPD positive subject were compared to the umbilical cord blood and patients with tuberculosis, diabetes and lung cancer. The culture is performed using heparinized whole blood diluted with a culture medium and infected with a low number of M. avium or M. tuberculosis $H_{37}Ra$ for 4 days by rotating the culture in a $37^{\circ}C$, 5% $CO_2$ incubator. In some experiments, methlprednisolone- or pentoxifyline were used to inhibit the immune response. To assess the role of the T-cell subsets, CD4+, CD8+ T-cells or both were removed from the blood using magnetic beads. The ${\Delta}$ log killing ratio was defined using a CFU assay as the difference in the log number of viable organisms in the completed culture compared to the inoculum. Results : 1. A trend was noted toward the improved killing of mycobacteria in PPD+ subjects comparing to the umbilical cord blood but there was no specific difference in the patients with tuberculosis, diabetes and lung cancer. 2. Methylprednisolone and pentoxifyline adversely affected the killing in the PPD+ subjects umbilical cord blood and patients with tuberculosis. 3. The deletion of CD4+ or CD8+ T-lymphocytes adversely affected the killing of M. avium and M. tuberculosis $H_{37}Ra$ by PPD+ subjects. Deletion of both cell types had an additive effect, particularly in M. tuberculosis $H_{37}Ra$. 4. A significantly improved mycobacterial killing was noted after chemotherapy in patients with tuberculosis and the ${\Delta}$ logKR continuously decreased in a 3 and 4 days of whole blood culture. Conclusion : The in vitro bactericidal assay by human whole blood culture model was settled using a CFU assay. However, the host immunity to M. tuberculosis was not apparent in the human whole blood culture bactericidal assay, and patients with tuberculosis showed markedly improved bacterial killing after anti-tuberculous chemotherapy compared to before. The simplicity of a whole blood culture facilitates its inclusion in a clinical trial and it may have a potential role as a surrogate marker in a TB vaccine trial.

A Study on the Improvement of Color Detection Performance of Unmanned Salt Collection Vehicles Using an Image Processing Algorithm (이미지 처리 알고리즘을 이용한 무인 천일염 포집장치의 색상 검출 성능 향상에 관한 연구)

  • Kim, Seon-Deok;Ahn, Byong-Won;Park, Kyung-Min
    • Journal of the Korean Society of Marine Environment & Safety
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    • 제28권6호
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    • pp.1054-1062
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    • 2022
  • The population of Korea's solar salt-producing regions is rapidly aging, resulting in a decrease in the number of productive workers. In solar salt production, salt collection is the most labor-intensive operation because existing salt collection vehicles require human operators. Therefore, we intend to develop an unmanned solar salt collection vehicle to reduce manpower requirements. The unmanned solar salt collection vehicle is designed to identify the salt collection status and location in the salt plate via color detection, the color detection performance is a crucial consideration. Therefore, an image processing algorithm was developed to improve color detection performance. The algorithm generates an around-view image by using resizing, rotation, and perspective transformation of the input image, set the RoI to transform only the corresponding area to the HSV color model, and detects the color area through an AND operation. The detected color area was expanded and noise removed using morphological operations, and the area of the detection region was calculated using contour and image moment. The calculated area is compared with the set area to determine the location case of the collection vehicle within the salt plate. The performance was evaluated by comparing the calculated area of the final detected color to which the algorithm was applied and the area of the detected color in each step of the algorithm. It was confirmed that the color detection performance is improved by at least 25-99% for salt detection, at least 44-68% for red color, and an average of 7% for blue and an average of 15% for green. The proposed approach is well-suited to the operation of unmanned solar salt collection vehicles.

HISTOMORPHOMETRIC AND REMOVAL TORQUE VALUES COMPARISION OF ROUGH SURFACE TITANIUM IMPLANTS (임프란트 표면처리 방법에 따른 골유착의 조직계측학적 분석 및 제거회전력 비교 연구)

  • Lee, Sang-Chul;Song, Woo-Sik
    • Maxillofacial Plastic and Reconstructive Surgery
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    • 제23권5호
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    • pp.396-405
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    • 2001
  • Osseointegrated implants are used for the fixation of dental prosthesis with good long-term clinical results. In an attempt to improve the quantity and quality of the bone-implant interface, numerous implant modification have been used. Implants surface modifications have been used such as titanium-plasma sprayed, hydroxyapatite-coating, sandblasted, sandblasted and acid-etched, acid-etched. Rough surface implants have greater implant surface area and enhance the bone-implant interface and improve stabilization. The purpose of present study was to evaluate light microscopic and scanning microscopic examinations and removal torque value of newly developed calcium phosphate blast and acid-etched implant in the femur of rabbits. Titanium plasma sprayed(TPS) implant served as controls. After 12 weeks of healing of the femurs of 12 rabitts, the implant-containing segments of femur were removed on bloc and bone block including sections. Histologic examination and histomorphometric and removal torque values comparision were made for two implants. Obtained results are follows: 1. Newly developed calcium phosphate blasted and acid-etched implants were in close contact with bone under light microscopic examinations. 2. New implants showed mean bone-to implant contact 59.8%, whereas TPS implants showed mean bone-to implant contact 54.5% (statistically no difference p<0.05). 3. New implants showed mean bone density 56.7%, whereas TPS implants showed mean bone density 49.2% (statistically difference p<0.05). 4. New implants demonstrated mean removal torque values 40.5Ncm, whereas the mean removal torque values of TPS implants ranged 39.3Ncm. No statistical differences(p<0.05) were observed between two groups of implants nor was there any difference between the two implants at the clinical level.

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Aerodynamic Characteristics of an Insect-type Flapping Wings (곤충 모방 플래핑 날개의 공력 특성)

  • Han, Jong-Seob;Chang, Jo-Won;Choi, Hae-Cheon;Kang, In-Mo;Kim, Sun-Tae
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 한국추진공학회 2007년도 제29회 추계학술대회논문집
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    • pp.311-314
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    • 2007
  • Aerodynamic characteristics of an insect-type flapping wings were carried out to obtain the design parameters of Micro Hovering Air Vehicle. A pair of wing model was scaled up about 200 times and applied two pairs of 4-bar linkage mechanism to mimic the wing motion of a fruit fly(Drosophila). To verify the Weis-Fogh mechanism, a pair of wings revolved on the 'Delayed Rotation'. Lift and drag were measured in conditions of the Reynolds number based on wing tip velocity of about 1,200 and the maximum angle of attack of 40$40^{\circ}$. Inertia forces of a wing model were also measured by using a 99.98% vacuum chamber and subtracted on measured data in air. In the present study, high lift effect of Weis-Fogh mechanism was appeared in the middle of upstroke motion.

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Self-Starting Characteristics of Blades for Vertical Axis Wind turbine (수직축 풍력발전용 날개의 기동력특성)

  • Kim, Sung-Hoon;Kim, Young-Ik;Lee, Joon-Min
    • Journal of Energy Engineering
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    • 제29권1호
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    • pp.34-43
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    • 2020
  • A study has been done for self-starting torque of vertical axis wind turbine blade. It is especially concentrated to evaluate the torque coefficient before starting rotation. Two different aerofoils(AMI903 and AMI904) are proposed to benchmark the possible best blade(supercritical airfoil) for self-starting performance. Torque coefficients in the tangential direction of rotation are given with respect to the angle of attack in terms of drag coefficient and lift coefficient. Torque coefficient shows that the effect of Reynolds number is minimal. The thicker blade(AMI904) between two different proposed airfoils has bigger torque coefficient, which is attributed to lower lift coefficient and higher drag coefficient.

A Study on the Deposition of Chitosan for Enhancing the Adsorption Ability of Activated Carbon (활성탄의 흡착력 향상을 위한 키토산 첨착에 관한 연구)

  • Ju, Han-Shin;Kim, Byung-Hoon;Jung, Sang-Chul;Ra, Deog-Gwan;Chung, Min-Chul;Ahn, Ho-Geun
    • Journal of Korean Society of Environmental Engineers
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    • 제22권2호
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    • pp.203-210
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    • 2000
  • The preparative methods of a chitosan-deposited activated carbon and its characteristics were studied by using three kinds of chitosan with different degree of deacetylation and average molecular weight. The procedure was consisted of the dissolution of chitosan into acid solution, impregnation of activated carbon, agitation, evaporation, and drying. When the chitosan-dissolved acid and its concentration, amounts of chitosan deposited, and agitation conditions were changed, the specific surface area, deposition state on surface, and stability were investigated, and amounts of Cr(VI) adsorbed was measured. In the preparation process, it was proper to agitate the chitosan-dissolved acetic acid solution at room temperature for 1hr. In the deposition of chitosan with low molecular weight, the specific surface area of activated carbon was greatly decreased even at low chitosan loading, but in the case of high molecular weight it was not nearly changed to 10wt% loading. It was known that chitosan was uniformly and physically deposited on activated carbon. The chitosan-deposited activated carbon was stable into the solution over about pH 6. The removal of Cr(VI) was remarkably enhanced by adding the adsorption function of chitosan to the surface of activated carbon with about 5wt% chitosan. It may be therefore used as an adsorbent for removing the pollutants in air and wastewater.

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The influence of implant diameter, length and design changes on implant stability quotient (ISQ) value in artificial bone (임플란트의 직경, 길이 및 디자인변화가 임플란트 안정성지수(ISQ)에 미치는 영향)

  • Lee, Jeong-Yol;Lee, Won-Chang;Kim, Min-Soo;Kim, Jong-Eun;Shin, Sang-Wan
    • The Journal of Korean Academy of Prosthodontics
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    • 제50권4호
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    • pp.292-298
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    • 2012
  • Purpose: The purpose of this study is to ascertain the stability of the implant by comparing the effects of the change of implant diameter, length and design on implant stability quotient. Materials and methods: To remove the variable due to the difference of bone quality, the uniform density (0.48 g/$cm^3$) Polyuretane foam blocks (Sawbones$^{(R)}$, Pacific Research Laboratories Inc, Vashon, Washington) were used. Implants (Implantium$^{(R)}$, Dentium, Seoul, Korea) were placed with varying diameters (${\phi}3.8$, ${\phi}4.3$ and ${\phi}4.8$) and length (8 mm, 10 mm and 12 mm), to assess the effect on implant stability index (ISQ). Also the influence of the design of the submerged and the non-submerged (SimplelineII$^{(R)}$, Dentium, Seoul, Korea) on ISQ was evaluated. To exclude the influence of insertion torque, a total of 60 implants (n = 10) were placed with same torque to 35 N. Using Osstell$^{TM}$ mentor (Integration Diagnostic AB, Sweden) ISQ values were recorded after measuring the resonant frequency, one-way ANOVA and Tukey HSD test results were analyzed. (${\alpha}$=0.05). Results: 1. The change of the diameter of the implant did not affect the ISQ (P>.05), but the increase of implant length increased the ISQ(P<.001). 2. The change in implant design were correlated with the ISQ, and the ISQ of submerged design was significantly higher than that of the non-submerged design(P<.05). Conclusion: In order to increase implant stability, the longer implant is better to be selected, and on the same length of implant, submerged design is thought to be able to get a higher ISQ than the non-submerged.

THE TREATMENT OF AN ANTEIOR CROSS-BITE WITH THE ERUPTION OF A MAXILLARY INCISOR USING $FR\ddot{A}NKEL$ III : CASE REPORT (상악중절치 맹출시기의 $Fr\ddot{a}nkel$ III를 이용한 전치부 반대교합의 치험례)

  • Lee, Sang-Youp;Kim, Hyun-Jung;Nam, Sun-Heun;Kim, Young-Jin
    • Journal of the korean academy of Pediatric Dentistry
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    • 제26권2호
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    • pp.323-330
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    • 1999
  • It is well recognized that a cross-bite tends to occur more frequently among Japanese, Chinese and Koreans more than among Europeans. A variety of functional appliances have already invented for the treatment of cross-bites. One of them is the FR III(by Rolf $Fr\ddot{a}nkel$) which applies a quite different philosophy based on the using vestibular region compared with other methods which utilize muscular forces applied directly on the teeth. The FR III also increases both the lack of muscular tension against the dental arch and the dentition and muscular forces which can then influence the teeth indirectly. This mechanism can achieve favorable developments with the basal bone, teeth, and alveolar bone. After using FR III to the anterior cross-bite patient with the eruption of a maxillary incisor the results were as follows: 1. Forward growth of maxilla and proclination of the upper incisor 2. Downward and backward rotation of the mandible 3. Increase the facial height 4. The case which was normal mandible, underdevelopmental maxilla, deeper overbite and more nagative overjet exhibited good prognosis

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