• 한국주조공학회지
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• 제10권6호
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• pp.528-537
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• 1990

7XXX aluminum alloy powders produced by the self-manufactured rotating disc atomizer were investigated to determine the influence of the atomization parameters on the particle size distributions in air atmosphere. The particle size distributions are almost always bimodal with the dominant mode on the large particle size. Average powder size of 7XXX aluminum alloy is $74/{\mu}m~125/{\mu}m$ when melt is poured with the rate of 9g /sec at 730$^{\circ}C$ on a rotating disc of 30㎜ diameter at 6300rad/sec. The mass of finer particle increased when disc diameter, angular velocity, pouring temperature increased and pouring rate decreased. The powder shapes of bimodal change from acicular to tear-drop and from tear-drop to ligament with increasing powder size. Powder shape was determined by the atomization mechanism and oxidation in liquid state. Microstructure of powders appeared to be cell and cellular dendrite. The SDAS of Al-7.9wt%Zn-2.4wt%Mg-1.5wt%Cu-0.9wt%Ni Powders is $0.8{\mu}m~1.0{\mu}m$ for the powders of $size＋44{\mu}m~53{\mu}m$ and $1.6{\mu}m∼1.8{\mu}m$ for the powders of $size＋105{\mu}m~125{\mu}m$, repectively.

• Clinics in Shoulder and Elbow
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• 제5권2호
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• pp.88-97
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• 2002

The purpose of this study was to compare the outcomes between arthroscopir repair and mini-open repair of medium and large rotator cuff tears in which arthroscopic repair was technically unsuccessful. We evaluated 76 patients of full-thickness rotator cuff tears, among them 42 patients had all-arthroscopic and 34 patients had mini-open salvage repairs. Patients who had acromioclavicular arthritis, subscapularis tear, or instability were excluded. There were 39 males and 37 females with mean age of 56 years (range,42 to 75 years). At a mean follow-up of 39 months (range, 24 to 64 months), the results of both groups were compared with regard to the UCLA and ASES shoulder rating scale s. Shoulder scores improved in all ratings in both groups (p > 0.05). Overall, sixty-six patients showed excellent or gr)of and ten patients showed fair or poor scores by the UCLA scale. Seventy-two patients satisfactorily returned to prior activity. Four showed unsatisfactory return. The range of motion, strength, and patient's satisfaction were improved postoperatively. There were no difference in shoulder scores, pain, and activity return between the arthroscopic and mini-open salvage groups (p > 0.05). However, Patients with larger size tear showed lower shoulder scores and less predictive recovery of the strength and function (p < 0.05). Postoperative pain was not different with respect to the size of the tear (p : 0.251). Arthroscopic repair of medium and large full-thickness rotator cuff tears had iln equal outcome to technically unsuccessful arthroscopic repairs, which were salvaged by conversion to a mini- open repair technique. Surgical outcome depended on the size of the tear, rather than the method of repair.

• Clinics in Shoulder and Elbow
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• 제13권1호
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• pp.64-71
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• 2010

목적: 회전근 개 파열과 동반되어진 상완 이두 건의 병변 및 치료 결과를 알아보고자 하였다. 대상 및 방법: 회전근 개 파열로 수술적 치료를 받고 후향적으로 상완 이두 건의 병변 여부를 확인할 수 있었던 92예를 대상으로 2년 이상 추시하였다. 상완 이두 건 병변은 건막염, 건의 마모 또는 비대, 파열, 불안정성의 4형태로 구분하였다. 회전근 개는 광범위 파열 중 4예를 제외하고는 모두 봉합하였으며 상완 이두 건 병변에 대해서는 변연 절제 30예, 건 절단 10예, 건 고정 8예, 재배치 4예를 시행하였다. 결과는 UCLA 평가 지수를 이용하였다. 결과: 상완 이두 건 병변을 보인 예가 70예 (76%)로 건막염은 19예, 건의 마모 또는 비대 22예, 파열 21예, 불안정성 8예의 병변을 보였다. 회전근 개 파열의 크기에 따라서 중범위 이하에서는 63%, 대범위 이상에서는 88%의 상완 이두 건 병변을 보였다. 치료 결과는 상완 이두 건 병변이 없었던 22예에서는 29.6점, 병변이 있었던 예 중 회전근 개 봉합을 시행하였던 66예에서는 28.3점이었다. 동반된 상완 이두 건을 절단하거나 재고정을 시행한 예에서는 28.2점이었다. 결론: 회전근 개 파열의 크기가 클수록 상완 이두 건 병변이 더 많이 발생하였고 형태도 보다 심하게 나타났다. 따라서 상완 이두 건 병변의 원인이 회전근 개 파열을 유발시키는 원인과 연관될 수 있다고 추측되었다. 동반된 상완 이두 건 병변의 치료로 건 절단이나 건 고정이 동통 완화에 효과적일 수 있다고 사료되었다.

• Clinics in Shoulder and Elbow
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• 제16권1호
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• pp.1-9
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• 2013

목적: 단순 방사선 사진상에서 견봉 및 상완골 대결절의 퇴행성 변화의 정도와 회전근 개 파열의 크기 사이의 연관성을 알아보고자 하였다. 대상 및 방법: 견관절의 자기 공명 영상을 시행한 퇴행성 회전근 개 파열 실험군 234예와 회전근 개 파열이 없는 대조군 284예 등 총 518예를 대상으로 하였다. 견관절 방사선 단순 촬영에서 퇴행성 변화의 정도를 관절와-상완 관절의 퇴행성 변화를 제외한 견봉과 대결절에서 골극의 길이와 형태의 변형에 따라 분류하였고, 자기 공명 영상에서 회전근 개의 파열의 정도 및 전층 파열의 크기를 분류하였다. 회전근 개의 파열의 정도와 크기에 따른 견봉 및 상완골 대결절의 퇴행성 변화 정도와의 연관성에 대해 알아 보았다. 결과: 견관절 단순 방사선 사진에서 보이는 견봉 및 상완골 대결절의 퇴행성 변화에 따른 MRI상 회전근 개 파열의 정도는 유의한 차이를 보였고(p<0.001), 견봉 및 상완골 대결절의 단순 방사선상 퇴행성 변화가 증가할수록 회전근 개 파열의 크기가 커지는 경향이 있었으며(p<0.001), 부분층 파열 보다 전층 파열 가능성이 높은 것으로 나타났다(p<0.001). 또한 고령 및 여자에서 회전근 개의 파열이 더 심하다는 결과를 얻었다(p<0.001, p<0.001). 결론: 퇴행성 회전근 개 파열 환자에서 견관절의 단순 방사선 사진상 견봉 및 상완골 대결절의 퇴행성 변화가 심할수록 회전근 개 파열의 크기가 더 크고, 나이와 성별도 관련 인자 중 하나로 사료된다.

• Clinics in Shoulder and Elbow
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• 제18권4호
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• pp.211-216
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• 2015

Background: Few studies have investigated magnetic resonance (MR) characteristics of traumatic posterosuperior rotator cuff tears involving the supraspinatus and infraspinatus. We hypothesized that traumatic rotator cuff tears may have MR characteristics distinguishable from those of non-traumatic tears. Methods: Preoperative MR arthrography and intraoperative tear size measurements were compared in 302 patients who underwent MR arthrography and subsequent arthroscopic rotator cuff repairs for traumatic (group T, 61 patients) or non-traumatic (group NT, 241 patients) tears. The inclusion criteria for both groups were posterosuperior full-thickness rotator cuff tear and age between 40 and 60 years. For group T, traumas were limited to accidental falls or slips, or sports injuries, motor vehicle accidents; injuries were associated with acute onset of pain followed by functional shoulder impairment; and time between injury and magnetic resonance imaging (MRI) was 6 weeks or less. Results: In group T, 72.1% of shoulders (44 patients) had tendon tears with blunt edges while 27.9% of shoulders (17 patients) had tears with tapering edges. In contrast, 21.2% of patients in group NT (51 patients) had blunt-edge tears, while 78.8% (190 patients) of tears had tapering edges. These results were statistically significant (p<0.001) and estimated odds ratio was 9.6. The size of tear did not vary significantly between groups. Conclusions: We found no exclusive MR characteristic to define traumatic tears. However, oblique coronal MRI of traumatic tears showed a significant tendency for abrupt and rough torn tendon edges and relatively consistent tendon thicknesses (without lateral tapering) compared to non-traumatic cuff tears.

• 펄프종이기술
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• 제29권1호
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• pp.7-12
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• 1997

This study was intended to investigate the proper shape and size of calcium carbonate for the improvement of paper properties and its end use performance. We loaded calcium carbonate of various shapes and size in the handsheet and measured their physical and optical properties. Results obtained from the study are summarized as follows : 1. Due to different particle shapes and sizes, precipitated calcium carbonate (PCC) contributed greater to bulk improvement than ground calcium carbonate (GCC). Scalenohedral form of PCC produced the bulkiest sheet, GCC made the sheet bulkier as average particle size increases. 2. Tensile strength increased as average particle size was increasing. GCC kept tensile strength more effectively than PCC. The effect of particle size on tensile strength was much more pronounced as filler addition level was increasing. 3. Over the average particle size of 6.99$\mu$m, GCC gave much higher burst strength and internal bond than PCC did. In the filler levels of 20% and 30%, GCC by using bigger size fillers showed 50~100% improvement in some cases than PCC at the same filler content. 4. Tear strength increased as average particle size was increasing. At the filler level of 30%, PCC decreased tear greatly. 5. Over the average particle size of 13.56$\mu$m, GCC kept bending stiffness greater than PCC. Due to its shape, Scalenohedral form of PCC showed higher stiffness than others at the same particle size. 6. Cubic and acicular form of PCC improved light scattering coefficient very effectively. Light scattering coefficient of GCC decreased as average particle size increased. 7. Both of particle shape and size of filler were important factor in developing optical properties and bending stiffness. Particle size was the only important factor in developing other strength properties

• Elastomers and Composites
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• 제5권1호
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• pp.69-74
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• 1970

The influence of various calcium carbonate on the physical properties of natural rubber have teen carries out extensive experiments on compounding. Final evaluation was made through various kinds of physical test-tensile strength, modulus, tear strength and hardnees-including particle size. The results are as follows: 1. Generally, tile tensile strength, modulus and tear strength showed the similar tendency in various calcium carbonate compounding. 2. The maximum volume of general using have been obtained with 150 phr calcium carbonate in $NR-CaCO_3$ compounding. 3. The particle size of domestic calcium carbonate showed $1.0\mu-2.6\mu$.

• Clinics in Shoulder and Elbow
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• 제19권3호
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• pp.125-129
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• 2016

Background: Superior migration of humeral head has been conventionally determined by measuring the acromiohumeral distance (AHD), We sought to devise a novel measurement system more reliably and accurately than AHD. We described a structural landmark called 'C-line'. In this study, we investigated the clinical usefulness of 'step-off of the C-line (SOC)' compared to that of AHD. Methods: The C-line formed from the medial margin of the proximal humeral head continuing up to the inferior margin of the articular glenoid and then to the lateral border of the scapula. The superior migration of the humeral head triggered by a rotator cuff tear introduces a discontinuity in this C-line. We measured the distance of this discontinuity. We enrolled 144 patients who underwent a rotator cuff repair. We selected 58 controls who didn't have any cuff lesions apparent on magnetic resonance imaging. Using radiographs derived from standardized true anteroposterior views of the shoulder, we measured the SOC and the AHD. We used t-tests for statistical analyses. Results: A rotator cuff tear was associated with an increase in SOC and a decrease in AHD. In control group, the mean SOC was $1.29{\pm}1.71mm$ and AHD was $9.71{\pm}2.65mm$. In cuff tear group, the mean SOC was $3.15{\pm}3.41mm$ and AHD was $8.28{\pm}1.76mm$. The mean SOCs of the patient group in relation to the mean SOC of the control group according to tear size, the SOCs of medium tear and lager groups showed statistically significant increase (p<0.05). Conclusions: The SOC may be a similarly effective to diagnose cuff tears of medium size and larger compared with AHD.

• Clinics in Shoulder and Elbow
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• 제10권2호
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• pp.160-166
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• 2007

목적: 다발성 회전근 개 파열에서 일차 복원술의 결과와 결과에 영향을 주는 인자를 분석하고자 하였다. 대상 및 방법: 1997년에서 2003년 사이에 두 개 이상 건이 이환된 회전근 개 파열에 대하여 일차 복원술을 시행한 후 2년 이상 추시된 19예(평균 연령 64.8세)를 대상으로 UCLA score의 변화를 조사하고, 외상, 능동적 운동, 견봉-상완골간 간격, 파열의 크기, 면적 등과 UCLA score사이의 상관 관계를 Pearson 선형 상관계수(PLCC)를 이용하여 검증하였다. 결과: UCLA score는 평균 9.4에서 26.1로 전 예에서 뚜렷이 증가하였으나 Ellman 기준상 53%에서 우수, 47%는 불량의 결과를 보였다. 외상, 능동적 거상, 견봉-상완골 간격 및 파열의 크기는 UCLA score와 상관관계가 없었으나 파열 면적은 UCLA score와 역 상관관계가 있었으며(PLCC=-0.696) MRI상 극하근의 Goutallier등급 III단계 이상 변성이 있는 경우는 불량한 결과를 보였다. 결론: 다발성 회전근 개 파열에서 일차 복원술의 결과는 53%에서 만족스러웠다. 큰 파열 면적, 극하근의 심한 변성은 불량 예후인자로 사료된다.

• Clinics in Shoulder and Elbow
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• 제7권1호
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• pp.5-9
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• 2004

회전근 개 파열과 동반된 관절 내 변화의 전체빈도는 활액막염 (63%), 관절순 이상(54%), 이두박 건 활차의 이상(53%), 이두박 건 이상(41%), 상완골두(30%) 및 관절와(20%) 순 이었으며. 이두박 건 장두, 이두박 건 활차, 관절와의 관절염 변화 등의 경우 2군에서 호발하였다. 또한 수술 시 치료가 필요했던건 주 변화의 경우는 2군에서 이두박 건 활차, 골두, 관절순 및 활액막에서 빈도가 증가하였다.