• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제38권6호
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• pp.332-336
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• 2012

Objectives: This study sought to evaluate fixation methods and determine the best method for the postoperative stabilization of maxillary osteotomy. For our analysis we performed a three-dimensional finite element analysis of stress distribution on the plate, screw, and surrounding bone, as well as displacement onto the plate. Materials and Methods: We generated a model using synthetic skull scan data; an initital surface model was changed to a solid model using software. Modified anterior segmental osteotomy (using Park's method) was made using the program, and four different types of fixation methods were used. An anterior load of 100 N was applied on the palatal surface of two central incisors. Results: The Type 1 (L-shaped) fixation method gave stresses of 187.8 MPa at the plate, 45.8 MPa at the screw, and 15.4 MPa at the bone around the plate. The Type 2 (I-shaped) fixation method gave stresses of 186.6 MPa at the plate, 75.7 MPa at the screw, and 13.8 MPa at the bone around the plate. The Type 3 (inverted L-shaped) fixation method gave stresses of 28.6 MPa at the plate, 29.9 MPa at the screw, and 15.3 MPa at the bone around the plate. The Type 4 (I-shaped) fixation method gave stresses of 34.8 MPa at the plate, 36.9 MPa at the screw, and 14.9 MPa at the bone around the plate. The deflection of the plates for the four fixation methods was 0.014 mm, 0.022 mm, 0.017 mm, and 0.018 mm, respectively. Conclusion: The Type 3 (inverted L-shaped) fixation method offers more stability than the other fixation methods. We therefore recommend this method for the postoperative stabilization of maxillary osteotomy.

• 한국HCI학회논문지
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• 제2권1호
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• pp.33-39
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• 2007

디지털 컨버전스 제품은 복잡한 정보 구조로 인한 인지적 과부하로 메뉴로 부터 효과적인 정보 인출의 방해를 초래하고 있다. 이러한 인지적 과부하를 완화하기 위해서 현재까지 크게 두 가지 방법(메뉴의 폭과 깊이에 관련된 물리적 방법과 메뉴 타이틀에 관련된 어의적 방법)을 사용하여 효과적인 메뉴구조를 만들기 위하여 노력하여 왔다. 본 연구는 visual search에 수반되는 Fixation과 Fixation Duration을 사용한 또 다른 어의적 방법론을 제안하여 메뉴구조 설계 방법으로서의 효능을 입증하고자 한다. 특히, Fixation은 인간의 인지 모델에 따라 자동적으로 이루어지기 때문에 Fixation을 통해 정보 구조와 인지 모델간의 일치 여부를 파악할 수 있으므로 인지적으로 잘 설계된 메뉴 구조는 Fixation 수와 Duration이 잘못 설계된 메뉴구조보다 적다는 가설이 성립된다. 이러한 가설의 검정을 위하여 본 연구에서는 Eye-Tracking 장비를 사용하여 메뉴 수정 전 후의 Fixation 수와 Duration을 측정하여 비교하였다. 그 결과 수정 후의 Fixation 수와 Duration이 유의하게 감소됨으로서 수정 후의 메뉴구조가 수정 전보다 효과적인 메뉴구조임을 알 수 있다. 다시 말해서 본 연구에서 제안한 visual search에 수반되는 Fixation과 Fixation Duration을 사용한 메뉴구조 설계 방법론이 효과적인 방법이라는 것이 증명되었다.

• Journal of Korean Neurosurgical Society
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• 제66권4호
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• pp.476-481
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• 2023

Objective : The latest version of the Leksell Gamma Knife Icon^TM allows for mask- and frame-based fixation. Although mask fixation provides fractionated treatment and immobilization using a noninvasive method, it is not free from collision. The authors investigated the collision problem with a modified mask fixation method. Methods : This study presents a case of two meningiomas in the frontal area, where a collision occurs in the occipital area. A modified mask fixation method was introduced to avoid the collision : first, the edges of the head cushion were cut off and polystyrene beads with a diameter of approximately 5 cm were removed. Next, the head cushion was sealed using a stapler. Finally, the head cushion was flattened in the adapter. We compared the shot coordinates, 3-dimensional (3D) error, clearance distance, and vertical depth of the head cushion between the initial and modified mask fixations. Results : When comparing the initial and modified mask fixations, the difference in the shot coordinates was +10.5 mm along the y-axis, the difference in the 3D error was approximately 18 mm, and the difference in clearance was -10.2 mm. The head cushion was approximately 8 mm deeper in the modified mask fixation. Conclusion : Based on these findings, we recommend a modified mask fixation method for gamma knife radiosurgery using ICON with a collision.

• Journal of Korean Neurosurgical Society
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• 제61권2호
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• pp.180-185
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• 2018

Objective : Many lumbosacral fixation techniques have been described to offer a more screw-bone purchase. The forward anatomical fixation parallel to the endplate is still the most preferred method. Literature revealed little knowledge regarding the mechanical stability of lumbosacral trans-endplate fixation compared to the traditional trans-pedicular screw fixation method. The aim of this study is to assess the pull-out strength of lumbosacral screws penetrating the end plate and comparing it to the conventional trans-pedicular screw insertion method. Methods : Eight lumbar and eight sacral vertebrae, with average age 69.4 years, Left pedicles of the 5th lumbar vertebrae were used for trans-endplate screw fixation, group 1A, right pedicles were used for anatomical trans-pedicular screw fixation, group 1B. In the sacral vertebrae, the right side S1 pedicles were used for trans-endplate fixation, group 2A, left side pedicles were used for anatomical trans-pedicular screw fixation, group 2B. The biomechanical tests were performed using the axial compression testing machine. All tests were applied using 2 mm/min traction speed. Results : The average pull-out strength values of groups 1A and 1B were $403.78{\pm}11.71N$ and $306.26{\pm}17.55N$, respectively. A statistical significance was detected with p=0.012. The average pull-out strength values of groups 2A and 2B were $388.73{\pm}17.03N$ and $299.84{\pm}17.52N$, respectively. A statistical significance was detected with p=0.012. Conclusion : The trans-endplate lumbosacral fixation method is a trustable fixation method with a stronger screw-bone purchase and offer a good alternative for surgeons specially in patients with osteoporosis.

• ALGAE
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• 제21권4호
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• pp.479-483
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• 2006

In preparation of the biological samples for electron microscopy, the chemical fixation by glutaraldehyde, paraformaldehyde, and OsO4 has been generally used for a long time. However, the chemical fixation method has some problems: the infiltration time is a little bit long and the ultrastructure of cell or tissue transforms before complete fixation of sample. So, recently, cryo-fixation is considered more often in biomedical field. In this study, we compared High Pressure Freezing (HPF) method with chemical fixation method using a algal sample (Ptilota filicina J. Agardh), which was difficult to fix using chemical fixation method. In chloroplast, the ultrastructure of thylakoid lamella and phycobilisome can not show clearly by chemical fixation. In this study we could observe the ultrastructure of thylakoid lamella and phycobilisome of chloroplast very clearly using HPF fixation. An improved images of ultrastructures of nucleus, mitochondrion and floridean starch could obtain. These results suggest that HPF method is very useful method in algal specimen for electron microscopy.

• 대한기계학회논문집A
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• 제33권4호
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• pp.430-439
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• 2009

Posterior Cruciate Ligament (PCL) plays an important role in knee extension. Rotational instability due to injured PCL can be restored by various PCL reconstruction methods. In this study, the initial lengthening affected by fixation device and location was demonstrated, and furthermore, the slippage and the relationship between lengthening ratio and slippage ratio in the calcaneus and soft tissue fixation methods was newly suggested. Eight specimens of proximal tibia and Achilles tendon grafts were harvested from four cadavers and divided into four groups in regard to the four different types of transtibial fixation techniques. The cyclic load ranged from 50 N to 250 N applied to each graft fixed to proximal tibia in 55 degrees. The initial lengthening ratio to the total elongation has been approximately constant regardless of the fixation methods. The soft tissue fixation method with an interference screw showed about 56.4% slippage ratio to the total elongation and the same method with a double cross-pin presented about 45.4% slippage ratio. The soft tissue fixation method with an interference screw demonstrated approximately 2 mm less total elongation and about 13% more slippage than lengthening because of poor fixation compared to the same method with a double cross-pin.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제13권4호
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• pp.412-420
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• 1991

Seventeen rigid screw fixation and sixteen nonrigid wire fixation cases of mandibular sagittal slit ramus osteotomy were selected to compare postoperative dental and skeletal changes. A constructed horizontal plane was drawn seven degrees under sella-nasion plane and detailed cephalometirc assessment was applied to serial radiographic films taken before surgery($T_0$), immediately after surgery($T_1$), and at least six months after surgery($T_2$). Linear and angular positional changes were measured and analyzed statistically using paired t-test method and percent of positional changes(amount of post-op change/amount of intra-op change)${\times}100$. The results were as follows; 1. It was 29.4% in rigid fixation cases and 37.5% in nonrigid fixation cases comparing the postoperative positional change of more than 2mm at point B. So rigid fixation method was slightly more stable. 2. In nonrigid fixation cases, the positional change might be caused by incomplete bony union at the osteotomy site and soft tissue tension acting on this site. 3. In rigid fixation cases, the positional change might be caused by interaction between relapse tendency of protracted condyle-proximal segment and neighboring soft tissue tension.

• 한국의류학회지
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• 제42권2호
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• pp.342-359
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• 2018

This research investigated the relationship between the amount of fixed pigment and the color of silk dyed with three types of fermented indigo powder dye under different temperatures and pH, by reduction or nonreduction method. Amount of fixed pigment was analyzed using the Ultimate 3000 HPLC-DAD instrument and the color of dyed silk was measured using the X-rite spectrocolorimeter. All silk samples dyed by reduction method showed PB color. The amount of indigotin fixation was dependent on the dyeing temperature and pH regardless of the indigotin composition in the dye. Indirubin was less dependent upon the dyeing condition in the reduction dyeing and its fixation was minimum level. Dyeing conditions which can maximize the indigotin fixation were $50^{\circ}C/pH$ 11 and $70^{\circ}C/pH$ 7 conditions in reduction dyeing. Color of silk showed more redness ($a^*$) thus higher PB color when the indigotin fixation was low and indirubin fixation was relatively high. Indirubin fixation was very low with slightly better fixation by nonreduction method. More reddish color was obtained by nonreduction dyeing, and by more alkaline dyebath.

• Journal of Trauma and Injury
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• 제20권2호
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• pp.72-76
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• 2007

Purpose: The purpose of this clinical trial was to evaluate the fixation method for treating alveolar fractures in an emergency department. Methods: The efficiency of using the fixation method was judged on the basis of clinical criteria. Stability, occlusion state, bleeding amount after fixation, operation time, and difficulties during procedural operation were recorded. Results: Eight patients were enrolled in this study. In all instances, the fixation method was effective in bleeding control. Each patient had a noticeable decrement in bleeding. A wire was used for four of the eight patients, and nylon strings was used for the others. The average operation time was 6.3 minutes for the wire patients and 2.8 minutes for the Nylon string patients. No specific problem was identified during the procedural operation. However, the difference in the fixation material influenced the effectiveness of the procedure, the operation time, and the satisfaction of the doctor. Conclusion: In the emergency department, the fixation method using wire or nylon string in the treatment of alveolar fractures is effective in bleeding control

• 대한의생명과학회지
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• 제13권4호
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• pp.361-368
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• 2007

Biological samples can be fixed either by chemical method by using chemical solution or physical methods by using heat treatment. The problem in traditional heat fixation is unsatisfactory quality due to uneven heat conduction in specimen and loss of inner cell contents. Chemical fixation method also bears several intrinsic problems like the limit in specimen size, time consumption in fixative impregnation, and loss of low molecular weight cell components. These factors deteriorate the quality of fixed specimen, thus limit the magnification and contrast of tissue pictures. Microwave heat has been reported to be a good alternative to current chemical methods to overcome these problem. In this study, we tried to introduce the microwave energy method to routine fixation work in hospital. We replaced chemical fixative with saline to provide moderate reaction condition, and used frozen section to reduce time for sample preparation. Temperature was measured at each experiment. The fixation of rat kidney tissue with 2.45 GHz electromagnetic wave and saline showed similar result to the control group fixed with traditional chemical method. Human tumor tissue fixed with 2.45 GHz electromagnetic in frozen section was improved in terms of histochemistry of PAS and immunohistochemistry of tumor marker like cytokeratin. Total turnaround time was reduced from $24\sim38$ h to to $2\sim4$ h. In conclusion, the quality of samples prepared by microwave heating method was at least as good as that of traditional method. If the condition for the fixation of different specimens is standardized, this new method could be applied to routine work in hospital, and could save working time as well.