• 구강회복응용과학지
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• 제40권3호
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• pp.125-134
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• 2024

목적: 구강 스캐너를 이용해 상악, 하악 스캔을 시행 후 교합 스캔을 하는 과정에서 어떠한 범위를 스캔했을 때 가장 정확한 교합 인기가 되는지를 파악하고자 하였다. 연구 재료 및 방법: 성인 30명을 대상으로 교합지를 사용하여 교합점을 채득하고 이를 기준으로 다양한 범위의 협측 교합 스캔의 결과를 비교하였다. 총 5개 영역(상악 치아를 기준으로 좌우 양측의 제1소구치에서 제2소구치, 제1소구치에서 제1대구치, 제1소구치에서 제2대구치, 제2소구치에서 제1대구치, 양측 견치)의 협측 교합 스캔을 시행하였으며, 이후 협측 교합 스캔파일을 CAD 프로그램을 통해 해당하는 범위 치아의 협측 부위만 남겨두고 데이터 편집 및 정렬을 통해 스캔 파일에서 교합 되는 영역을 확인하였다. 이후 교합지로 얻어진 교합점과 스캔 파일에서 얻어진 교합 영역의 일치도를 비교하였으며, 등분산성 T-test를 통해 통계 분석하였다(α = 0.05). 결과: 각 그룹간 정렬 성공률과 정렬 실패율은 양측 견치에서는 각각 77.23%, 40.85%로 나타났고, 양측 제1소구치에서 제2소구치에서 각각 68.23%, 28.89%, 양측 제1소구치에서 제1대구치에서 63.76%, 29.97%, 양측 제1소구치에서 제2대구치에서는 61.31%, 32.04%, 그리고 양측 제2소구치에서 제1대구치는 67.55%, 27.46%로 나타났다. 양측 견치에서의 결과는 상악 모든 구치부 스캔 결과와 비교했을 때 정렬 성공률과 실패율 모두 높은 양상이 나타났다. 정렬 성공률에서 구치부를 스캔 범위에 따른 통계적 유의성은 나타나지 않았으나, 구치부와 양측 견치의 결과 비교에서는 양측 제2소구치에서 제1대구치의 스캔 결과를 제외하고 통계적 유의성이 관찰되었다. 정렬 실패율에서는 구치부 스캔 범위에 따른 통계적 유의성은 나타나지 않았고, 구치부와 양측 견치의 결과에서는 모두 통계적 유의성이 관찰되었다. 결론: 교합 협측 스캔 채득 시 전치부를 스캔할 경우 구치부를 스캔할 때보다 교합 되는 영역이 더 많이 나타나며, 구치부를 스캔할 경우 범위에 따른 교합 인기의 유의미한 차이는 나타나지 않는다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.46-49
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• 2003

Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties, Until now, strengthening of the copper at toy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the at toy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conduct ing material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the copper matrix composites of high strength and electric conductivity In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process in order to manufacture the intermediary materials for the carbon nanofiber reinforced Cu matrix nanocomposite and align mechanism as well as optimized drawing process parameters are verified via experiments and numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of $10~20\mu\textrm{m}$ In length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber. Optimal parameter for drawing process was obtained by experiments and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc Lower reduction areas provides the less rupture of cu tube is not iced during the drawing process. Optimal die angle was between 5 degree and 12 degree. Relative density of carbon nanofiber embedded in the copper tube is higher as drawing diameter decrease and compressive residual stress is occurred in the copper tube. Carbon nanofibers are moved to the reverse drawing direct ion via shear force caused by deformation of the copper tube and alined to the drawing direction.

• 한국광학회지
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• 제27권6호
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• pp.223-228
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• 2016

액정과 같은 단축 이방성 분자들의 정렬 정도에 따라 달라지는 복굴절으로부터 상대 복굴절 ${\Delta}n_{rel}$를 구하고 ${\Delta}n_{rel}$과 방향질서변수(orientational order parameter) S의 관계를 탐색하였다. 무질서한 분포를 하고 있는 경우를 포함하여 액정의 정렬정도를 달리 표현할 수 있는 분포함수를 도입하고 이 분포함수를 사용하여 질서변수 S가 0부터 1까지 변하도록 액정분자들의 정렬정도를 달리하며 ${\Delta}n_{rel}$과 S를 수치계산 하였다. 이 계산 결과로부터 s와 ${\Delta}n_{rel}$는 $S=(1+a){\Delta}n_{rel}-a{\Delta}n^2_{rel}$와 같이 준선형적인 관계를 만족하며 a는 $n_o{\frac{{\Delta}n}{4}}$으로 근사할 수 있음을 확인하였다. 또한 복굴절으로부터 Vuks의 방법에 따라 구한 분자분극의 이방성과 Neugebauer의 방법에 따라 구한 분자분극의 이방성이 각각 질서변수 S와 또 다른 준선형 관계식들을 따름을 보였다.

• PNF and Movement
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• 제13권2호
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• pp.103-109
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• 2015

Purpose: Abdominal breathing exercises are recommended to activate the breathing muscles and the pelvic floor muscles, as well as to increase postural alignment during exhalation. The purpose of this study was to clarify the effect of improving abdominal muscle strength on menstrual pain in women in their twenties using abdominal breathing exercises. Method: In this study, 32 female university students were included as the subjects. The subjects were divided into two groups based on the area of menstrual pain: lumbar pain (n=16) and lower abdomen pain (n=16). The abdominal breathing positions were divided into two positions, which included a hook lying position and hip and knee flexions at $90^{\circ}$ in the supine position. Exercises were used to strengthen the abdominal muscles during exhalation. Four sets of the exercises were completed three times a week over the course of eight weeks. The degree of pain was measured using the Numeric Rating Scale (NRS). Muscle thickness was measured using an ultrasound. Result: The thickness of the transverse abdominis (TrA) and internal oblique (IO) increased in the lower abdomen pain group. However, thickness of the external oblique (EO) did not increased following abdominal breathing. No significant difference in posture was identified in the lower abdomen group. TrA thickness increased significantly in the lumbar pain group. However, thickness did not increase significantly in the lumbar pain group. In addition, the lumbar pain group experienced no significant effects on posture. IO thickness increased following hip and knee flexions at $90^{\circ}$ in the lumbar pain group. Menstrual pain decreased following intervention in both groups. There was no significant difference in the degree of pain reduction between both groups. Conclusion: As examples of alternative medicine, abdominal breathing exercises may be effective in decreasing menstrual pain.

• 공업화학
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• 제22권1호
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• pp.81-86
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• 2011

자기 조립성 염료인 Sunset Yellow-FCF 수용액은 상온에서 농도 25 wt%부터 schlieren 구조의 액정상을 보이기 시작하여, 28 wt% 이상이면 완전한 네마틱 액정상으로 관찰되었다. 전단배향에 의한 코팅으로 광학적 이방성 필름을 제조하기 위해서는 30 wt% 이상의 농도가 필요하였다. 액정 색소의 농도, 코팅속도, 건조 온도, 상대습도 등 코팅 변수가 최종 박막필름의 두께, 투과도에 미치는 영향 분석에 의하면, 최종 필름의 두께에는 용액의 농도가 가장 큰 영향을 주었으며, 평행방향의 투과도에는 건조 온도와 농도의 영향이 가장 컸다. 특히 Sunset Yellow-FCF의 농도 증가로 전단코팅에 의한 배향성이 개선되고 높은 편광도를 갖는 필름제조가 가능하였다. 본 실험에서는 33 wt%의 Sunset Yellow-FCF 수용액을 사용하면, 89.7~98.7%의 편광도를 갖는 광학적 이방성 필름이 제조되었다.

• The Journal of Advanced Prosthodontics
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• 제15권6호
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• pp.290-301
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• 2023

PURPOSE. The study aimed to determine the influence of implant angulation on the trueness of multi-unit implant impressions taken through different techniques and strategies. MATERIALS AND METHODS. As reference models, three partially edentulous mandibular models (Model 1: No angulation; Model 2: No angulation for #33, 15-degree distal angulation for #35 and #37; Model 3: No angulation for #33, 25-degree distal angulation for #35 and #37) were created by modifying the angulations of implant analogues. Using a lab scanner, these reference models were scanned. The obtained data were preserved and utilized as virtual references. Three intraoral scanning (IOS) strategies: IOS-Omnicam, ISO-Quadrant, and IOS-Consecutive, as well as two traaditional techniques: splinted open tray (OT) and closed tray (CT), were used to create impressions from each reference model. The best-fit alignment approach was used to sequentially superimpose the reference and test scan data. Computations and statistical analysis of angular (AD), linear (LD), and 3D deviations (RMS) were performed. RESULTS. Model type, impression technique, as well as interaction factor, all demonstrated a significant influence on AD and LD values for all implant locations (P < .05). The Model 1 and SOT techniques displayed the lowest mean AD and LD values across all implant locations. When considering interaction factors, CT-Model 3 and SOT-Model 1 exhibited the highest and lowest mean AD and LD values, respectively. Model type, impression technique, and interaction factor all revealed significant effects on RMS values (P ≤ .001). CT-Model 3 and SOT-Model 1 presented the highest and lowest mean RMS values, respectively. CONCLUSION. Splinted-OT and IOS-Omnicam are recommended for multi-unit implant impressions to enhance trueness, potentially benefiting subsequent manufacturing stages.

• 대한족부족관절학회지
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• 제13권2호
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• pp.162-168
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• 2009

Purpose: To evaluate the efficiency of the minimally invasive percutaneous plate osteosynthesis (MIPPO) with locking compression plate (LCP) for distal tibial metaphyseal intra-articular fracture compared with extra-articular fracture. Materials and Methods: From February 2006 to June 2008, 21 patients with distal tibia metaphyseal intra-articular fracture and 20 patients with extra-articular fracture were treated operatively by MIPPO technique with LCP and followed for at least one year. In the group with intra-articular fracture, mean age was 48.85 years old and a mean follow-up was 15 months. In the other group with extra-articular fracture, mean age was 52.35 years old and a mean follow-up was 14.5 months. The type of fracture was evaluated using the AO/OTA classification and open-fractures were according to the Gustilo-And gron classification. Radiologic evaluation with fracture healing and tibial alignment, clinical evaluation with Olerud and Molander ankle score and restriction of motion were done for treatment. Results: According to AO/OTA classification, There were 21 type A, 15 type B, 5 type C. Average union time of the intra-articular fracture (type B, C) was 18.7 weeks. Average union time of the extra-articular fracture (type A) was 17.1 weeks. All fractures were healed without malunion. There were no difference of mean restriction angle between intra-articular fracture (ankle dorsiflexion was 3.57 degree, plantar-flexion was 5.95 degree) and extra-articular fracture (ankle dorsiflexion was 3 degree, plantar-flexion was 3.75 degree). There were no difference of Olerud and Molander ankle score between them as a mean score of intra-articular and extra-articular was 89.25, 91.25 each other. As a complication, there were 3 case of skin necrosis, 8 case of discomfortable skin tenting by plate and 1 superficial infection, but could be healed by conservative care. Conclusion: MIPPO technique, combined articular reduction, with LCP of distal tibial metaphyseal fracture was a good method with high functional recovery.

• 한국주조공학회지
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• 제11권4호
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• pp.293-302
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• 1991

Aluminum alloy matrix composites reinforced with various amounts of $Al_2O_3$ short fibers have been produced by a combined technique of rheo-compocasting and hot extrusion. Distribution of fibers in the composites fabricated by rheo-compocasting was relatively uniform. A good degree of uniaxial fiber alignment has been achieved by hot extrusion, but a lot of fibers fractured during extrusion. The tendency of fiber fracturing increases as the aspect ratio and the amount of fibers increase. Relatively good bonding between fiber and matrix was obtained by the formation of $MgAl_2O_4$ and Mg(Al, Fe)$_2O_4$ at the interface between fiber and matrix. In extruded composites, fiber-strengthening effect was relatively small since a lot of fibers fractured during hot extrusion. On the other hand, dispersion strengthening effect may increase. In order to improve the fiber strengthening effect, it is important to optimize the extrusion condition with consideration of metal flow in extrusion die.

• Carbon letters
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• 제19권
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• pp.89-98
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• 2016

Taguchi’s experimental design was employed in the melt spinning of molten mesophase pitch to produce carbon fibers. The textures of the obtained carbon fibers were radial with varied crack angles, as observed by scanning electron microscopy and polarized optical imaging. The diameter, crack angle, preferred orientation, and tensile modulus of the produced samples were examined to investigate the influence of four spinning variables. The relative importance of the variables has been emphasized for each characteristic. The results show that thicker carbon fiber can be obtained with a smaller entry angle, a higher spinning temperature, a reduced winding speed, and an increased extrusion pressure. The winding speed was found to be the most significant factor in relation to the fiber diameter. While it was observed that thicker carbon fiber generally shows improved preferred orientation, the most important variable affecting the preferred orientation was found to be the entry angle. As the entry angle decreased from 120° to 60°, the shear flow was enhanced to induce more ordered radial alignment of crystallite planes so as to obtain carbon fibers with a higher degree of preferred orientation. As a consequence, the crack angle was increased, and the tensile modulus was improved.

• 한국도로학회논문집
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• 제16권5호
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• pp.173-182
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• 2014

PURPOSES : The purpose of the study is to a) explore the operating speed of trucks on rural highways affected by road geometry, and thereby b) develop a predictive model for the operating speed of trucks on rural highways. METHODS : Considering that most of the existing studies have focused on cars, the current study aimed to predict the operating speed of trucks by conducting linear regression analysis on the speed data of trucks operating on the linear-curved-linear portions of the road as a single set. RESULTS : The operating speed in the plane curve portion increased with the length of the curve, and decreased with a lower vertical grade and a smaller curve radius. In the straight plane portion, the operating speed increased with a larger curve radius(upstream), and decreased with an increase in the change of the vertical grade, depending on the length of the vertical curve. CONCLUSIONS : This study developed estimation models of truck for operational speed and evaluated the degree of safety for horizontal and vertical alignments simultaneous. In order to represent whole area of the rural highway, the models should be ew-analyzed with vast data related with road alignment factor in the near future.