• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.287-293
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• 2016

The equatorial region of the Earth's ionosphere exhibits large temporal variations in electron density that have significant implications on satellite signal transmissions. In this paper, the first observation results of the variations in the trough of the equatorial ionospheric anomaly at the permanent Global Navigation Satellite System (GNSS) site in Chuuk (Geographic: $7.5^{\circ}N$, $151.9^{\circ}E$; Geomagnetic: $0.4^{\circ}N$) are presented. It was found that the daytime Global Positioning System (GPS) total electron content (TEC) values vary according to the 27 day period of solar rotation, and that these trends show sharp contrast with those of summer. The amplitudes of the semi-annual anomaly were 12.4 TECU (33 %) on $19^{th}$ of March and 8.8 TECU (23 %) on $25^{th}$ of October respectively, with a yearly averaged value of 38.0 TECU. The equinoctial asymmetry at the March equinox was higher than that at the October equinox rather than the November equinox. Daily mean TEC values were higher in December than in June, which could be interpreted as annual or winter anomalies. The nighttime GPS TEC enhancements during 20:00-24:00 LT also exhibited the semi-annual variation. The pre-midnight TEC enhancement could be explained with the slow loss process of electron density that is largely produced during the daytime of equinox. However, the significant peaks around 22:00-23:00 LT at the spring equinox require other mechanisms other than the slow loss process of the electron density.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.61-67
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• 2001

Objectives : To demonstrate the preventive effect on post-operative spinal deformity of the laminoplasty compared with laminectomy for spinal cord tumor. Methods : Sixteen patients who underwent laminoplasty and 89 patients who underwent lamenectomy were reviewed retrospectively after removal of spinal cord tumors between February 1981 and December 1999. The mean follow-up period after laminoplasty and laminectomy were 29 months(range, 12-49 months) and 66 months(range, 6-120 months) respectively. Patients were observed neurologically and radiologically. Results : Postoperative kyphosis was observed 17 patients(19%) in the laminectomy group, but was not observed in the laminoplasty group. Postoperative slipping was observed 16 patients(18%) in the laminectomy group, but was not observed in the laminoplasty group. Complications such as postoperative scoliosis, rotation, and swan-neck deformity were observed in the laminectomy group, but were not observed in the laminoplasty group. Conclusions : Laminoplasty prevented postoperative spinal deformities after removal of spinal cord tumors, and afforded anatomic reconstruction of the vertebral arch. Additionally, appropriate patient selection maximizes the chance of optimal neurologic outcomes and minimizes complications. Laminoplasty appears to warrant further evaluation as an alternative to wide laminectomies for exposure of intraspinal tumors.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.2
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• pp.115-126
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• 2016

In the process of ship building, it is known that the maintenance of working period and saving cost are one of the important part during the logistics of blocks transportation. Precise operational planning inside the shipyard plays a big role for a smooth transportation of blocks. But many problems arise in the process of block transportation such as the inevitable road damage during the transportation of the blocks, unpredictable stockyard utilization of the road associated with a particular lot number, addition of unplanned blocks. Therefore, operational plan needs to be re-established frequently in real time for an efficient block management. In order to find the shortest path between lot numbers, there are several representative methods such as Floyd algorithm that has the characteristics of many-to-many mapping, Dijkstra algorithm that has the characteristic of one-to-many mapping, and the A* algorithm which has the one-to-one mapping, but many authors have published without the mutual comparisons of these algorithms. In this study, some appropriate comparison have been reviewed about the advantages and disadvantages of these algorithms in terms of precision and cost analysis of calculating the paths and planning system to operate the transporters. The flexible operating plan is proposed to handle a situation such as damaged path, changing process during block transportation. In addition, an operational algorithm of a vacant transporter is proposed to cover the shortest path in a minimum time considering the situation of transporter rotation for practical use.

• The Korean Journal of Physiology and Pharmacology
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• v.23 no.1
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• pp.71-79
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• 2019

Body surface potential map, an electric potential distribution on the body torso surface, enables us to infer the electrical activities of the heart. Therefore, observing electric potential projected to the torso surface can be highly useful for diagnosing heart diseases such as coronary occlusion. The BSPM for the heart of a patient show a higher level of sensitivity than 12-lead ECG. Relevant research has been mostly based on clinical statistics obtained from patients, and, therefore, a simulation for a variety of pathological phenomena of the heart is required. In this study, by using computer simulation, a body surface potential map was implemented according to various occlusion locations (distal, mid, proximal occlusion) in the left anterior descending coronary artery. Electrophysiological characteristics of the body surface during the ST segment period were observed and analyzed based on an ST isointegral map. We developed an integrated system that takes into account the cellular to organ levels, and performed simulation regarding the electrophysiological phenomena of the heart that occur during the first 5 minutes (stage 1) and 10 minutes (stage 2) after commencement of coronary occlusion. Subsequently, we calculated the bipolar angle and amplitude of the ST isointegral map, and observed the correlation between the relevant characteristics and the location of coronary occlusion. In the result, in the ventricle model during the stage 1, a wider area of ischemia led to counterclockwise rotation of the bipolar angle; and, during the stage 2, the amplitude increased when the ischemia area exceeded a certain size.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.45-54
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• 2019

In this study, we analyze the rattle noise of a power takeoff (PTO) driveline and develop a PTO driveline resonance model. We measured the rattle noise of the PTO driveline on the output shaft and, by analyzing the rattle noise in the time domain, we determine that the engine expansion stroke period matches the sound pressure of rattle noise. This finding helped us demonstrate that the rattle noise is caused by the collision between the PTO driving gear and the gear driven by the engine expansion stroke; the torsional vibration caused by this collision is affected by the angular velocity fluctuation of the PTO drive shaft. By measuring the angular velocity of the PTO drive shaft, we confirm that the angular velocity fluctuation of the engine flywheel tends to excessively amplify the PTO drive shaft angular velocity fluctuation. We conclude that the resonance, which occurs when the operating frequency of the engine is close to the natural frequency of the tractor power transmission system, causes the excessive angular velocity fluctuation of the PTO drive shaft. We performed a modal analysis of the PTO driveline resonance and, using the characteristic equation, we show that the resonance occurs when the engine rotation speed is close to 850 rpm, which matches the natural frequency of the PTO driveline.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.5
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• pp.380-388
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• 2019

Jet engine modulation(JEM) signals are widely used for target recognition. These signals coming from a potentially hostile aircraft provide specific information about the jet engine. In order to obtain the number of blades, which is uniquely provided by the JEM signal, one must extract the spool rate, which is the rotation speed of the blades. In this paper, we propose an algorithm to extract the spool rate from a weak JEM signal. A criterion is developed to extract the spool rate from the JEM signal by analyzing the intensity of the JEM signal component. The weak signal is first subjected to a high-pass filtering-based process, which modifies it to facilitate spool rate extraction. We then apply a peak detection process and extract the spool rate. The technique is simpler than the existing CEMD or WD method, is accurate, and greatly reduces the time required.

• Clinics in Shoulder and Elbow
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• v.22 no.4
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• pp.220-226
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• 2019

Background: This retrospective study was undertaken to evaluate mid-term clinical and radiological outcomes of lattisimus dorsi (LD) tendon transfer in patients with irreparable massive rotator cuff tears (MRCT). We hypothesize that LD tendon transfer would provide safe and satisfactory clinical outcomes at mid-term follow-up. Methods: From November 2008 to December 2016, 23 patients ($57.5{\pm}4.4years$; 20 male, 3 female) who underwent LD tendon transfer for massive tears, were enrolled. Inclusion criteria were irreparable MRCT. Exclusion criteria included full thickness subscapularis tear, rotator cuff arthropathy, anterosuperior rotator cuff tear, and osteoarthritis. Mean follow-up period was $4.7{\pm}4.0years$ (range, 2-12 years). Clinical assessment (American Shoulder and Elbow Surgeons [ASES], University of California, Los Angeles [UCLA], Simple Shoulder Test [SST]) and radiographic assessment (osteoarthritis [OA], acromiohumeral distance [AHI]) were evaluated. Results: ASES, UCLA and SST scores, and range of motion (ROM), except internal rotation, improved significantly at the last followup (p<0.05). Also, AHI was significantly improved at the last follow-up, from 6.6 mm to 8.2 mm (p=0.008). At the final follow-up, the radiologic stages of the glenohumeral osteoarthritis were determined as stage 1 in 9 patients, stage 2 in 10 patients, stage 3 in 2 patients, and stage 4 in 2 patients. Complications were observed in 21.7% cases: 3 re-tears and 2 infections were noted in our study. Conclusions: LD tendon transfer for irreparable MRCT provides satisfactory clinical outcomes at mid-term follow-up. Mild degenerative osteoarthritis (stage 1, 2) of the shoulder joint are common at the mid-term follow-up. Also, complications such as tear, infection should be considered.

• Physical Therapy Rehabilitation Science
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• v.9 no.4
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• pp.230-237
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• 2020

Objective: To investigate the physical appearance and therapeutic changes that occur with the performance of Schroth exercise in patients with scoliosis. Design: Randomized controlled trial. Methods: Fifteen subjects with maximum curvature of the lumbar who were diagnosed with idiopathic scoliosis had volunteered to participate in the study. Eight subjects were included in the experimental group where they performed the Schroth Therapeutic Exercise and the other seven were included in the control group. The experimental group underwent 2 hours of weekly treatment for 12 weeks, while the control group did not during the same period based on the decisions of patients or guardians. The Mann-Whitney rank test was carried out to compare the treatment results of the two groups, and the comparison within the group was done by Wilcoxon signed-rank test. The vertebral rotation angle (VRA) was by Scoliometer, and difference of rotated and curved portion volume (DV) between both sides on the major curvature portion measured by 3D human body scanning system. Results: In the experimental group, 12 weeks of Schroth exercise therapy has significant improved in correction rate (CR) in Cobb's angle (CA), VRA, and DV between both sides on the major curvature portion (p<0.05), while significant differences were not found between the groups regarding weight bearing difference in both feet (WD) and DV (p<0.05). Conclusions: Schroth exercise performance showed significant changes in the patient's therapeutic changes (CA, VRA), but the physical appearance (DV, WD) was not significant, indicating that external changes in the treatment goal setting are more difficult goals to achieve.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.166-171
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• 2021

Background: This study aims to compare the clinical outcomes of steroid injections during the rehabilitation period after arthroscopic rotator cuff repair (ACRC). Methods: Among patients who underwent ARCR, 117 patients who met the inclusion and exclusion criteria were enrolled. Pain and range of motion (ROM) recovery at the 3-, 6-, and 24-month follow-up visits and functional outcome at the 24-month follow-up were compared between 45 patients who received ultrasound-guided subacromial steroid injection at postoperative week 4 or 6 and 72 patients who did not. Functional outcome was assessed using the American Shoulder and Elbow Surgeons (ASES) score and Constant score. Healing of the repaired tendon and retear were observed at the 6-month follow-up via magnetic resonance imaging (MRI) or computed tomography (CT) arthrography. Results: At the 3-month follow-up, the steroid injection group showed lower visual analog scale scores than the control group (p<0.05) and showed faster recovery of forward flexion and internal rotation (p<0.05). From the 6-month follow-up, the two groups did not show differences in pain and ROM, and the ASES score and Constant score also did not significantly differ at the 24-month follow-up. The two groups did not differ in retear rate as determined by MRI or CT arthrography at the 6-month follow-up. Conclusions: This study demonstrated that ultrasound-guided subacromial steroid injection at 4 or 6 weeks after ARCR leads to quick pain reduction and ROM recovery until 3 months after surgery. Therefore, subacromial steroid injection is speculated to be an effective and relatively safe method to assist rehabilitation.

• Journal of East-West Nursing Research
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• v.16 no.1
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• pp.70-75
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• 2010

Purpose: Nursing students face constant threats of blood-borne infections such as HIV, Hepatitis B, and Hepatitis C during their clinical rotation period. This study was done to determine the frequency and risk of the exposure to blood and body fluids. Methods: The data was collected using a questionnaire. Ninety eight junior & senior nursing students were participated in this study. Results: 75.6% of the participants reported more than once during practicum. The exposure occurred most frequently while checking the blood glucose (65.3%). The general ward (45.3%) was the most frequent site for the occurrence of the exposure. However, only eight cases (10.7%) were reported to the medical or nursing personnel in charge. Conclusions: This study shows nursing students are in a great risk of the exposure to blood & body fluid. The risk is highest in the general ward during checking the blood glucose. Thorough education on preventive measures, should be provided to nursing students prior to clinical practium.