• 천문학회보
• /
• 제42권2호
• /
• pp.50.1-50.1
• /
• 2017

The Non-Principal Axis (NPA) rotators can be clues to spin evolutionary processes of asteroids because their excited spin states evolve due to either internal or external forces. The NPA rotation of (5247) Krylov was confirmed by Lee et al. (2017) based on KMTNet photometric observations during the 2016 apparition. We conducted follow-up observations in 2017 apparition using the 0.6-2.1m telescopes in the northern hemisphere to determine the spin state and shape model of this asteroid. We found that it is rotating in the Short Axis Mode (SAM) based on the determined rotation period ($P_{\psi}=374.6hr$) and precession period ($P_{\phi}=67.48hr$). The greatest and intermediate principal inertia moments are nearly the same as $I_b/I_c=0.94$, but the smallest principal inertia moments are nearly half that of the others, $I_a/I_c=0.43$. This ratio of principal inertia moments suggests that dynamically equivalent shape of this asteroid is close to that of a prolate ellipsoid. In this presentation, we will provide the physical model of (5247) Krylov to discuss its possible spin evolutionary processes that acted on its spin.

• Journal of Advanced Marine Engineering and Technology
• /
• 제38권9호
• /
• pp.1146-1149
• /
• 2014

단자 표식이 불분명한 3상유도전동기에서 고정자 권선의 극성을 판별하는 데는 외부 여자전류에 의해 유도되는 기전력 특성에 기초하거나 또는 회전자의 잔류자기를 이용하는 방법이 가능하다. 회전자의 잔류자기로 유도되는 권선에서의 기전력은 자속 크기와 수동 구동의 회전자 속도 및 위상 관계에 따라 정해지며 이 같은 극성 판별이 작업현장에서 가능하려면 기전력의 크기가 멀티테스터로 확인될 수 있는 정도이어야 하고 또한, 코일 간 위상 특성이 극성 판별에 적합해야 한다. 잔류자기에 의한 기전력들이 3상 평형 관계에 있다면 전체 합성 전압은 권선들의 극성 연결 상태가 정상일 때 0이 되어야 하는 한편, 극성 연결의 오류 시에는 상대적으로 큰 출력 전압을 나타낸다는 점에서 본 연구에서는 각 경우에 대한 특성을 분석하였다. 또한, 잔류자기에 의한 판별 방식을 실험용 전동기에 적용하여 극성의 정상 및 이상 상태에서의 출력 파형을 비교함으로써 제시된 방식이 극성 판별 방법으로서 현장에서 용이하게 활용될 수 있는지를 확인한다.

• Clinics in Shoulder and Elbow
• /
• 제7권2호
• /
• pp.65-69
• /
• 2004

Purpose: The purpose of this study is to evaluate the short-term clinical outcome of the capsulolabral repair using absorbable suture anchor in traumatic anterior instability of shoulder. Materials and Methods: From June 2000 to September 2001, 15 shoulders with recurrent anterior instability were operated with arthroscopic Bankart repair using absorbable suture-anchor 'PANALOK' (Mitek, westwood, MA), and were followed up over 1 year (average; 13 months). The mean age was 23-years. There were fourteen males and one female. The mean duration from the initial symptoms to the operation was 24 months. Associated pathologies were Hill-Sachs defect in 12 cases, SLAP in 6 cases, and partial rotator cuff tear in 2 cases. The results were evaluated by patien's satisfaction, Modified Rowe Score in regard to joint stability, mobility, pain and function in comparison with the preoperative ones, and other complications. Results: At the last follow-up, the total Rowe Score increased from 38 points to 92 points. There were no recurrence and 14 patients among 15 patients gained pre-operative level of sports activity and no other complications. Conclusion: Effective capsulolabral repair could be obtained by the absorbable anchoring without any untoward complications. This procedure is simple and safe one and this system can be a good substitute for the metallic anchor.

• Clinics in Shoulder and Elbow
• /
• 제18권3호
• /
• pp.138-143
• /
• 2015

Background: To evaluate the effect of preoperative fatty degeneration of deltoid and teres minor muscles on the clinical outcome in patient with reverse total shoulder arthroplasty (RTSA). Methods: Nineteen patients with RTSA were enrolled. The mean follow-up period was 16.1 months. The fatty degeneration of three distinct parts in each deltoid and the teres minor muscle was measured using a preoperative magnetic resonance imaging. Postoperatively, the muscle strengths for forward elevation (FE), abduction (Abd), and external rotation (ER) were measured using a myometer at the last follow-up. The parameters for clinical outcome were Constant Score (CS) and Korean Shoulder Score (KSS). Results: The number of cases was 10 in group 1 and 9 in group 2. The strength of FE and Abd were significantly higher in group 1 (p<0.001 and p<0.001, respectively), and the strength of ER was not different significantly between two groups (p=0.065). For the clinical outcome, both CS and KSS were higher in group 1 (p=0.002 and p=0.002, respectively). The number of patients in group A was 11, and group B was 8. Although there was not a significant difference in terms of FE and Abd between group A and B (p=0.091, p=0.238), ER was significantly higher in group A (p=0.012). We did not find a significant difference in the clinical scores (CS, p=0.177 and KSS, p=0.238). Conclusions: These findings suggest the importance of a preoperative evaluation of the fatty degeneration of deltoid and teres minor muscles for predicting postoperative strength and clinical outcome.

• Clinics in Shoulder and Elbow
• /
• 제11권1호
• /
• pp.13-18
• /
• 2008

견관절의 모든 병적 상황의 성공적인 치료에는 정확한 진단이 요구된다. 이학적 검사는 견관절 질환의 검사에 필수적인 요소이다. 통증, 근력의 저하, 운동범위의 감소, 그리고 불안정성은 다양한 견관절 병태생리에 의해 발생하는 가장 흔한 증상들이다. 따라서, 견관절 질환을 가진 환자에게 정교한 임상적 접근이 필수적이다. 다양한 진단적 검사와 임상적 측정을 포함한 표준화된 평가가 견관절 복합체에서 한 구성요소를 특정하게 검사함으로써 진단적 정확도를 향상시킨다. 대부분의 경우, 신중한 이학적 검사가 진단과 확진 및 추가적 조사를 위해 선택적으로 시도될 수 있는 영상학적 시술과 같은 특정 진단 기술을 계획하거나 제공하게 된다.

• Clinics in Shoulder and Elbow
• /
• 제20권2호
• /
• pp.84-89
• /
• 2017

Background: Common and effective treatments for calcific tendinitis involve needling procedures. However, it has been widespread practice to refer patients with calcific tendinitis, which is a predominantly orthopedic condition, to radiology department. The purpose of this study was to compare clinical and radiological outcomes after ultrasound-guided needling for calcific tendinitis between the orthopedics and radiology department. Methods: Seventy-seven shoulders (Group 1) and 38 shoulders (Group 2) treated in the radiology and orthopedic department, respectively. A fellowship-trained orthopedic surgeon and a musculoskeletal radiologist each performed the procedure of ultrasound-guided needle decompression with subacromial steroid injection. Clinical outcomes was evaluated using the visual analogue scale for pain (pVAS) and the American Shoulder and Elbow Surgeons (ASES) shoulder score before treatment and at each follow-up. The pre- and postneedling size and shape of the calcific deposits were compared between the two groups. Results: We analyzed a total of 56 shoulders for Group 1 and 32 shoulders for Group 2. The mean age and sex ratio of the patients no significantly different. We found that the mean decrease in the diameter of calcification between pre- and post-needling was 9.0 mm for Group 1 and 13.1 mm for Group 2; the difference was significantly larger in Group 2 than in Group 1. Both groups showed improved pVAS and ASES scores after needling but the extent of these improvements did not differ with the type of operator. Conclusions: Needling decompression performed by orthopedic surgeons could a viable option for the treatment of calcific tendinitis.

• Clinics in Shoulder and Elbow
• /
• 제21권3호
• /
• pp.127-133
• /
• 2018

Background: This study was undertaken to evaluate the outcome of the arthroscopic capsular release for adhesive capsulitis of the shoulder. Methods: This study retrospectively investigated thirty shoulders in 29 patients who presented with recalcitrant adhesive capsulitis and underwent arthroscopic treatments. Other than typical findings of adhesive capsulitis, combined pathologies in the glenohumeral joint and subacromial space were evaluated by arthroscopy. Clinical evaluations were performed using the Constant's score and ranges of motion (ROM) at preoperative, 6 months postoperatively and at the final follow-up. Results: Our study included 17 women and 12 men with a mean age of 53.8 years (range, 34-74). Mean follow-up duration was 24 months (range, 12-40 months). Assessment of combined pathologies revealed that partial rotator cuff tear of less than 25% thickness, was most common (overall 83.3%; with bursal 57% and articular 23%). Subacromial synovitis and adhesion were also frequent (53.3%). The Constant score and ranges of motion significantly improved at the final follow-up, compared with preoperative levels. However, clinical results at 6 months postoperatively were found to be significantly inferior to those observed at the final follow-up ($p{\leq}0.001$ for all factors). Functional impairment was the major complaint in 59.3% patients at the 6 months follow-up. Conclusions: Although arthroscopic capsular release yielded favorable outcome at the mean 24 months follow-up, pain and motion limitations at 6-month postoperatively persisted in more than 50% of our patients. While combined pathologies were commonly encountered during arthroscopy, although their effects on surgical outcome in adhesive capsulitis remains unclear in this study.

• 대한물리의학회지
• /
• 제8권1호
• /
• pp.41-48
• /
• 2013

PURPOSE: This study was to determine the effect of the plane of movement (sagittal plane vs. scapular plane) and shoulder flexion angle ($90^{\circ}$ vs. $130^{circ}$) during scapular protraction exercises in healthy subjects by investigating the elecromyographic (EMG) activities of the serratus anterior (SA), upper trapezius (UT), and pectoralis major (PM). METHODS: Twenty-one healthy subjects participated in this study. Subjects performed maximal scapular protraction at the $90^{\circ}$ or $130^{\circ}$ shoulder flexion angles in the sagittal or scapular planes. Surface EMG was recorded from the SA and UT, and PM muscles. Dependent variables were examined by 2 (plane) ${\times}$ 2 (angle) repeated measures of analysis of variance (ANOVA). RESULTS: Significantly increased EMG activities in the SA and UT were found during scapular protraction exercise at the $130^{\circ}$ shoulder flexion angle in the sagittal and scapular plane. Also, EMG activity of the PM significantly decreased at the $130^{\circ}$ shoulder flexion angle in the sagittal plane and the $90^{\circ}$ and $130^{\circ}$ shoulder flexion in the scapular plane. CONCLUSION: we recommend scapular protraction exercise at the $90^{\circ}$ shoulder flexion in the sagittal plane to selectively strengthen the SA muscle with limitation of upper trapezius activity and at the $130^{\circ}$ shoulder flexion in the scapular plane to selectively strengthen the SA muscle with limitation of pectoralis major activity.

• 천문학회보
• /
• 제43권1호
• /
• pp.33.1-33.1
• /
• 2018

The differential rotational properties of early-type galaxies (ETGs) revealed by integral field spectroscopy surveys is arguably one of the most exciting findings in the galaxy evolution study during the past decade. Numerical studies have shown that galaxy mergers under various configurations can reproduce the observed distribution of ETG spin. However, we suggest an alternative scenario for the spin evolution of a large fraction of ETGs. Using the Horizon-AGN simulation, we follow the spin evolution of 10037 color-selected ETGs more massive than 1010 Msun that are divided into four groups: cluster centrals (3%), cluster satellites (33%), group centrals(5%), and field ETGs (59%). We find a strong mass dependence of the slow rotator fraction, fSR, and the mean spin of massive ETGs. Although the environmental dependence is not clear in the fSR, it is visible in the mean value of the spin parameter. The environmental dependence is driven by the satellite ETGs whose spin gradually decreases as their environment becomes denser. Galaxy mergers appear to be the main cause of total spin changes in 94% of central ETGs of halos with Mvir > 1012.5 Msun, but only 22% of satellite and field ETGs. We find that non-merger induced tidal perturbations better correlate with the galaxy spin-down in satellite ETGs than mergers. Given that the majority of ETGs are not central in dense environments, we conclude that non-merger tidal perturbation effects played a key role in the spin evolution of ETGs observed in the local (z < 1) universe.

• Journal of Advanced Marine Engineering and Technology
• /
• 제39권1호
• /
• pp.19-27
• /
• 2015

최근에 국제해사기구(IMO)에서 선박 평형수 처리장치(Ballast water treatment system, BWTS)와 관련된 국제 규정을 강화함에 따라 이에 대응할 수 있는 BWTS 기술개발의 중요성이 대두되고 있다. 지금까지는 세계 각국에서 선박 평형수 처리기술을 처리방식에 따라 크게 물리적 방식(막분리, 원심분리, 자외선 등)과 화학적 처리방식(염소처리, 오존처리, 화확약품 등)으로 개발하여 왔으나, 기존의 기술 방식들은 추가적인 구동전력, 낮은 생산성, 잔류처리 문제 등으로 기술적인 보완이나 대안이 요구되고 있다. 본 연구에서는 기존과는 다른 새로운 방식의 기계식 방식 평형수 처리장치의 설계를 위한 유동해석 연구이다. 고속 회전하는 몇 가지 디스크 형상에 따라 유동에서 발생하는 여러 가지 유동특성을 전산유체해석(CFD)를 통하여 분석하였다. 평판형 및 계단형 형상에서는 반경을 따라서 국부적으로 공동현상이 발생가능하며, 원주형에서는 전단응력 강도를 높일 수 있었다.