• Elastomers and Composites
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• 제57권4호
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• pp.147-156
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• 2022

In this study, we chose a flat die to optimize a general die geometry. The optimization was aimed at obtaining a uniform velocity distribution across the exit of the die. For the optimization, the input and output design parameters were randomly computed, and response surfaces were generated to obtain statistical data for the minimum and maximum sensitivities computed during optimization. Subsequently, object functions with constraints were numerically computed to obtain the minimum errors in the velocity difference (i.e., variable "Outp" in this study). Finally, we obtained the candidate optimized dataset. Note that the current numerical computations were simultaneously conducted for an entire extruder, i.e., screw plus die. The numerical outlet velocity distributions in the modified die geometry tended to be much more uniform than the conventional distributions in the current optimization processes for this specific flat die.

• The Journal of Advanced Prosthodontics
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• 제8권2호
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• pp.150-157
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• 2016

PURPOSE. The modified lateral-screw-retained implant prosthesis (LSP) is designed to combine the advantages of screw- and cement-retained implant prostheses. This retrospective study evaluated the mechanical and biological complication rates of implant-supported single crowns (ISSCs) inserted with the modified LSP in the posterior region, and determined how these complication rates are affected by clinical factors. MATERIALS AND METHODS. Mechanical complications (i.e., lateral screw loosening [LSL], abutment screw loosening, lateral screw fracture, and ceramic fracture) and biological complications (i.e., peri-implant mucositis [PM] and peri-implantitis) were identified from the patients' treatment records, clinical photographs, periapical radiographs, panoramic radiographs, and clinical indices. The correlations between complication rates and the following clinical factors were determined: gender, age, position in the jaw, placement location, functional duration, clinical crown-to-implant length ratio, crown height space, and the use of a submerged or nonsubmerged placement procedure. RESULTS. Mechanical and biological complications were present in 25 of 73 ISSCs with the modified LSP. LSL (n=11) and PM (n=11) were the most common complications. The incidence of mechanical complications was significantly related to gender (P=.018). The other clinical factors were not significantly associated with mechanical and biological complication rates. CONCLUSION. Within the limitations of this study, the incidence of mechanical and biological complications in the posterior region was similar for both modified LSP and conventional implant prosthetic systems. In addition, the modified LSP is amenable to maintenance care, which facilitates the prevention and treatment of mechanical and biological complications.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제46권2호
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• pp.133-142
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• 2020

Objectives: In this study, we determined the incidence and pattern of screw loosening in patients who received dental implants. Materials and Methods: Patients who received implants between January 2008 and October 2013 and completed their prosthetic rehabilitation were evaluated for the incidence, frequency, and onset of screw loosening using dental charts and radiographs. The association between each factor and screw loosening was analyzed using the chi-square test and a multivariate analysis with binary logistic regression models (P<0.05). Results: Total 1,928 implants were placed in 837 patients (448 males, 389 females), whose follow-up period after loading varied from 0.25 to 70 months (mean period, 31.5 months). Screw loosening occurred in 7.2% of implants. Most cases occurred less than six months after loading. Among those, 22.3% experienced recurrent screw loosening. Screw loosening was most common in the molar region (8.5%) and frequently associated with an implant diameter of ≥5 mm (14.2%). External implant-abutment connections (8.9%) and screw-retained implant prostheses (10.1%) showed higher incidence of problems than internal implant-abutment connections and cement-retained implants, respectively. Screw loosening was most common in implant prostheses with single crowns (14.0%). Conclusion: Within the limits of the current study, we conclude that the incidence of screw loosening differs significantly according to the position of implant placement, the type of implant and manufacturer, implant diameter, the type of implant-abutment connection, the type of retention in the implant prosthesis, and the type of implant prosthesis.

• 한국식품영양과학회지
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• 제29권3호
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• pp.412-419
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• 2000

본 연구는 오징어, 쌀가루 및 탈지콩가루를 혼합하여, 압출성형 공정을 이용하여, 새로운 스낵제품을 만들고자 수행하였다. 실험실용 single-screw extruder를 이용하여 제품의 낮은 전단력과 높은 팽화율을 목적으로 수 차례 실험한 결과, 15.7%의 혼합물수분과 16$0^{\circ}C$의 조리 오도가 비교적 좋은 제품 생산조건으로 나타났다. 이 조건에서 냉동 건조 오징어가루나 아주 곱게 갈은 생 오징어를 다른 재료들과 혼합하여 최종 제품들을 만들었다. 전단력은 두 오징어 첨가제품간에 유의성 있는 차이는 없었으나, 팽화율의 경우는 생 오징어를 첨가하여 만든 제품이 냉동 건조시킨 오징어를 첨가하여 만든 제품에 비해 유의적으로 높았다. 소비자 관능검사 결과 생 오징어로 만든 제품이 냉동 건조시킨 오징어로 만든 제품에 비해 유의적으로 높았다. 소비자 관능검사 결과 생 오징어로 만든 제품이 냉동 건조시킨 오징어로 만든 제품에 비해 외관, 맛, 향, 그리고 전체적 면에서 선호도가 높았다. 결론적으로 본 연구는 단백질이 풍부한 오징어와 탈지 코가루를 쌀가루에 첨가하여 비교적 팽창이 잘된 스낵제품을 생산할 수 있는 조건을 제시하였으며, 이 결과는 차후 제품개발의 기반으로 사용할 수 있을 것이라고 본다.

• Journal of Periodontal and Implant Science
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• 제36권4호
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• pp.925-938
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• 2006

The aim of this study was to systematically investigate the complications of single implant-supported restorations followed more than 5-year. Thirty-five studies were selected for the systematic review. A total of 3932 single implants were included at the beginning of studies. Thirty-one implants were removed before loading and 91 implants after loading. The overall implant loss rate was 3.1 %. Implant losses were concentrated on the period between loading and 2-year follow-up, and, after a stable period, increased after 5-year follow-up. The mean marginal bone loss at single-tooth implants was well within 0.2 mm/year, i.e., acceptable annual bone loss by the implant success criteria. However, considerable amounts of single implants suffered a marginal bone loss at implant more than 0.2 mm/year. Fistula was a frequent biological complication in the early studies. The most frequent technical problem was a screw loosening, but its frequency was reduced after the use of a gold screw and torque controller. Within the limits of this study, the complications of single implants might be underestimated due to the lack of information about the biological and technical complications available in the relevant literature.

• Journal of Korean Neurosurgical Society
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• 제40권3호
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• pp.175-179
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• 2006

Objective : The surgical outcome of anterior lumbar interbody fusion[ALlF] with pedicle screw fixation for elderly isthmic spondylolisthesis was analyzed. Methods : Consecutive nineteen elderly patients [aged 65 years or more] with isthmic spondylolisthesis [Grade I or II] who underwent single level ALIF with pedicle screw fixation in 2002 were analyzed. Using clinical chart and mailed questionnaires, preoperative and postoperative Visual Analogue Scale[VAS] of back and leg pain and postopertive Macnab criteria were evaluated. Results : The mean age at the time of operation was 68.4 years [range 65 to 78 years]. Twelve patients underwent ALIF with percutaneous pedicle screw fixation. Seven patients underwent ALIF followed by posterior decompression and pedicle screw fixation. The postoperative complication rate was 10.5% [wound dehiscence in 1 patient and incisional hernia in 1 patient]. There was no postoperative major morbidity or mortality. At a mean follow-up duration of 30.7 months [range 25 to 35 months], 93.3% [14/15] of the patients showed excellent or good outcomes in terms of Macnab criteria. The mean VAS scores of back pain and leg pain significantly decreased after surgery. Conclusion : ALIF with pedicle screw fixation yielded favorable results for elderly isthmic spondylolisthesis in selected cases.

• 대한조선학회논문집
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• 제58권6호
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• pp.407-414
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• 2021

The manoeuvrability of a ship with an unwanted heel angle due to a maritime accident is changed from the original characteristics. The purpose of this study is to quantitatively investigate the change in the manoeuvring performance of a twin-screw ship under various hee angles and speed conditions. A series of free running model test campaigns were performed in the Ocean Engineering Basin of Korea Research Institute of Ships & Ocean Engineering (KRISO) for a twin-screw car ferry vessel. Turning circle test and zig-zag 10/10 and 20/20 tests were carried out on the heel angles of 0, -10, and -19.5 degrees. In addition, two-speed conditions were considered to understand the effect of ship speed. In order to examine the effect of the bilge keel, a heel angle of -22 degree where the bilge keel is exposed outside the water surface, was considered. Finally, the change of manoeuvring characteristics according to the heel angle for a twin-screw and a single-screw vessel is discussed.

• 대한족부족관절학회지
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• 제9권1호
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• pp.87-93
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• 2005

Purpose: We conducted this study to examine the clinical results of the proximal metatarsal wedge osteotomy using a single screw fixation and the distal soft tissue procedure in patients with moderate to severe hallux valgus deformity. Materials and Methods: Between February 2002 and February 2004, we performed these procedures on 12 patients (15 cases). The 6 cases of all patients had mild to moderate instability in the first MTC (metatarsocuneiform) joint. We estimated the clinical outcomes, the radiological findings and complications. Results: AOFAS score was improved from preoperative 41.5 points to 87.7 points lastly on average. The mean correction angle of HVA and IMA was $23.8^{\circ}$ and $6.6^{\circ}$, respectively. The mean position of tibial sesamoid was 2.67 before surgery and 0.87 after surgery. The mean shortening of the first metatarsal bone was 3.07 mm after surgery. There was no pain and complications on the first MTC joint except the breakage of screw in one case and instability of the first MTC joint was improved postoperatively. Conclusion: We obtained good clinical and radiographic outcomes in our series. So, proximal metatarsal wedge osteotomy using a single screw fixation and distal soft tissue procedure seems one of the good surgical treatments for moderate hallux valgus deformity.

• 한국식품과학회지
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• 제33권1호
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• pp.45-49
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• 2001

본 연구는 single-screw extrusion puffing을 이용하여 동태, 탈지콩가루의 양은 고정시키고, 쌀가루와 옥수수가루의 함량을 달리하여 제조한 압출 성형제품의 특성을 알아보고자 실행하였다. 각 제품에 있어 일반성분에서의 통계적인 차이는 나타나지 않았으며 품질특성에서는 쌀가루 100%로 제조한 제품이 다른 제품과 비교했을 때 팽화율이 높고, 밀도가 낮으며 전단력이 가장 낮게 나타나 유의성 있는 차이를 보여주었다(P<0.05). 100% 쌀가루제품이 색도에서도 명도가 가장 높았고, 관능검사의 전반적인 바람직성 검사에서도 선호도가 높게 나타났다. 결론적으로 수산식품인 동태와 탈지콩가루를 쌀가루에 첨가하여 옥수수가루보다 팽창이 잘된 압출성형제품을 전단력이 낮은 좋은 조건에서 생산할 수 있었다. 이 결과는 차후 제품 개발에 동태를 첨가시킨 쌀가루 스낵제품을 만들 수 있는 기초자료가 될 것으로 사료된다.

• Tribology and Lubricants
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• 제25권3호
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• pp.182-186
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• 2009

Extruders can be basically divided into bisk and screw type of extruders. Though plastic extruders are often used for its simplicity for water and oil transportation pumps, these days screw extruders are mostly used. Screws are used in many extrusion processes to manufacture complex and complicated shaped parts made of plastics, medicine materials, food, polymer composites, iron and ceramic powders, etc. Also, material correction of deformities is caused by flow and physicochemical reaction phenomenonand material extrusion is processed according to heat transfer. various material comes to hopper because extruder has function by blender and mixing of materials can go well before come out through dice. These change process is so complicated that process condition is decided by trial and error that process condition is underground mainly at extrusion molding process.