• Journal of the Korean earth science society
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• v.41 no.1
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• pp.19-30
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• 2020

To understand the impact of typhoons on Gamji gravel beach Taejongdae in Busan, we carried out beach profiling using a VRS-GPS system and a Drone photogrammetry for the typhoons 'Kong-rey' invaded in October 2018 and 'Danas' in July 2019. In addition, grain sizes are analyzed to investigate the overall distribution pattern of gravels on the beach, and the beach topography is surveyed periodically to confirm the recovery rate of the beach. Grain-size analysis reveals that mean gravel sizes, in general, become finer from -6.2Φ to -5.4Φ towards the east in the seashore line direction. Variation in mean sizes is obviously observed in the cross-shore direction. Gravels in the swash zone are relatively fine about -4.5Φ in size and equant in shape, whereas the coarse and oblate gravels ranged from -5Φ to -6Φ are found in the berm. Gamji gravel beach particularly has two lines of berms: a lower berm situated facing beach and an upper berm about 10 m landward. After the typhoon Kong-rey passed by, about 1.4 m of severe erosion in upper berm occurred, and the berm eventually disappeared. On the backshore of the upper berm about 50 cm of erosion took place so that the elevation became lower. However, tangible erosion was not observed in the lower berm. When typhoon Danas hit, rated as mild storm, both upper and lower berm were eroded out. However, about 50 cm of deposition occurred only in the backshore. Only three days later, the new lower berm was formed, meaning that sedimentation rate must be high. This result indicates that Gamji gravel beach is recovered very fast from erosion caused by the typhoons when it is under the fair-weather condition even though beach morphology changes dramatically in a short period of time. Gravel beach is estimated to be or evaluated very resilient to typhoon erosion.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.423-429
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• 2008

Background: The interest in robotic cardiac surgery has recently grown but there has not been much clinical research reported on this. The aim of this study is to examine our initial experience, since August 2007, with robotic cardiac surgery using the da $Vince^{TM}$ surgical system and to evaluate the feasibility and safety of it. Material and Method: Between August and December 2007, a total of 20 patients underwent robotic cardiac surgery using the da Vinci surgical system. For mitral valve repair (n=11), tricuspid valve repair (n=1), and ASD repair (n=1), cannulation, antegrade cardioplegia and transthoracic aortic cross-clamping were conducted for the right femoral vessels and the right internal jugular vein. For minimally invasive direct CABG (MIDCAB) (n=7), the internal thoracic artery (ITA) was harvested with the da Vinci surgical system. Result: The mean age of the patients was 50.1 (range: $26{\sim}78$) years. Three concomitant Maze procedures and one tricuspid annuloplasty were combined with mitral valve repair. The mean cardiopulmonary bypass time was $208.0{\pm}61.3$ minutes and the aortic cross clamp time was $158.8{\pm}40.6$ minutes. No patients showed more than mild mitral regurgitation after repair and the median hospital stay was 4 days. The robotic-harvested ITA was used for either left ITA (n=6) or bilateral ITA (n=1). The mean harvest time was $43.2{\pm}12.0$ minutes. The harvested ITA showed good flow and it was anastomosed under direct vision after left anterolateral thoracotomy. The patency of all the grafts was 100% (18/18) in MIDCAB. Conclusion: Robotic cardiac surgery using the da Vinci surgical system was variously adapted to areas such as mitral and tricuspid valve repair, ASD repair and ITA harvest for MIDCAB. The early results of the robotic cardiac surgery showed its safety and feasibility. With this primary report, we anticipate that clinical applications and further studies on robotic cardiac surgery using the da Vinci surgical system will be actively conducted in Korea.

• Progress in Medical Physics
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• v.16 no.1
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• pp.10-15
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• 2005

IAEA's guidance levels have been provided for western people to the end. Guidance levels lower than the IAEA'S will be necessary in view of Korean people's proportions. Therefore, we need to develope the standard doses for Korean people. And we conducted a nationwide survey of patient dose from x-ray examinations in Korea. In this study, the 278 institutions were selected from Members Book of Korean Hospital Association. The valid response rate was approximately 57.9%. Doses were calculated from the questionnaires by NDD method. We obtained the results were as follows; 1) General radiographic equipments were distributed for 42.0%, fluoroscopic equipments 29.4%, dental equipments 13.2%, CT units 8.1 % and mamographic units 7.2%. 2) According to classification by rectification, three-phase equipments were 29.9%, inverter-type generators 29.5%, single-phase equipments 25.5%, constant voltage units 9.0% and unknown units 6.0%. 3) According to classification by receptor system, film-screen types were 46.8%, CR types 26.8%, DR types 17.7% and unknown types 8.9%. 4) The number of examinations were chest 49.2%, spine 16.8% and abdomen 12.7%. 5) Patient doses were head AP 3.44 mGy, abdomen AP 4.25 mGy and chest PA 0.39 mGy.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.6 no.1
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• pp.1-9
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• 2013

Purpose: The purpose is to perform objective evaluation for rotator cuff using ultrasonography and validate factors influencing cuff integrity as well as efficacy of follow-up ultrasonography after unreamed antegrade intramedullary nailing for humerus fracture. Materials and Methods: Seventeen patients with an average age of $55.7{\pm}18.6$ years underwent antegrade intramedullary nailing for humerus fracture and follow-up ultrasonography of shoulder joint. Mean follow-up period was $43.5{\pm}32.2$ months. Intraoperative evaluation for preoperative cuff tear was performed, of which four cuffs were repaired by single row repair technique. Clinical evaluation included visual analogue scale (VAS), range of motion, Korean Shoulder Scoring System (KSS) and American Shoulder and Elbow Society (ASES) score. Ultrasonographic evaluation was performed on cuff integrity and protrusion of proximal nail tip as well. Radiographic evaluation included time to union, protrusion of proximal nail tip and migration of proximal interlocking screw which could affect shoulder joint function. Results: Mean VAS at last follow-up was $1.65{\pm}1.84$ points. Range of motion showed forward flexion of $137.0{\pm}33.5^{\circ}$, external rotation of $43.5{\pm}12.7^{\circ}$ and internal rotation of $16.4{\pm}2.0^{\circ}$ while KSS score and ASES score were $79.6{\pm}20.7$ and $83.7{\pm}17.0$ points, respectively. Bone union was demonstrated in all cases and average time to union was $3.4{\pm}1.3$ months. Migration of proximal interlocking screw was shown in 6 cases (35%). On ultrasonographic evaluation, there were normal in 8 (47%), weaving in 4 (24%), partial tear in 5 cases (29%), but no complete tear. Protrusion of proximal nail tip was demonstrated in 8 cases (47%) on plain radiographs whereas in 11 cases (65%) on ultrasonography and was associated with increasing age (p=0.038). Ultrasonographic weaving and partial tear was associated with protrusion of proximal nail tip (p=006), but not with repair of preoperative tear (p>0.05). Conclusion: Because weaving and partial tear on ultrasonography originated from protrusion of proximal nail tip, careful insertion of nail and meticulous repair of cuff during operation lead to stable fixation with satisfactory recovery of shoulder function follow-up ultrasonography can be a useful tool for evaluating protrusion of nail tip and rotator cuff tear, of which diagnosis is difficult on plain X-ray after antegrade intramedullary nailing for humerus fracture.

• Journal of Chest Surgery
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• v.30 no.1
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• pp.27-33
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• 1997

Retrograde myocardial protection is widely accepted in CABG operation because of the limitations of the antegrade method in the coronary arterial stenosis lesions. We analyzed 76 c ses of retrograde myocardial protection among 96 cases of CABG operation performed between April 1994 and August 1995, There were 48 males and 25 females, and the mean age was 58.2 $\pm$ 8.3 years. 53 patients (70%) were operated for unstable angina, 14 (18%) for stable angina, 6 (8%) for post-infarct angina, 1 (1%) for acute myocardial infarction, and 2()%) for failed PTCA. Preoperative coronary angiography revealed 3-vessel disease in 42 cases, 2-vessel disease in 11, 1-vessel disease in 10, and left main disease in 13 cases. We used SVG(63 cases), LIMA(69 cases), RIMA(11 cases), radial artery(6 cases), and gastroepiploic artery(1 case) for the grafts. Mean anastomosis was 3.2 $\pm$ 1.1. We protected the myocardium with antegrade induction and retrograde maintenance in all the cases except a case of retrograde induction and maintenance. During the aortic cross-clamping, blood cardioplegia was administered intermittently in 19 cases, and continuously in 57 In 39 cases, we used retrograde ardioplegia and antegrade perfusion of RCA graft simultaneously. We had no operative motality. Perioperative complications were arrhythmia in 15 cases, perioperatve myocardial infarction in 10, low cardiac output syndrome In 8, transient neurologic problem in 7, transient psychiatric problem in 6, ARF in 3, bleeding in 2, pneumonia in 2, wound infection in 1, and duodenal ulcer perforation in 1 . In this report, we experienced 76 cases of CABG operation with retrograde myocardial protection under the acceptable operative risk without operative mortality.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.56-63
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• 2004

Background: Patch angioplasty is an alternative surgical procedure to coronary artery bypass grafting (CABG) for left main coronary ostial stenosis. The purpose of this study is to evaluate the outcome of patch angioplasty by analyzing the short-term and long-term results. Material and Method: Twenty nine patients who had undergone patch angioplasty due to left main coronary ostial stenosis between July 1991 and May 2003 were enrolled in the study. The mean age of the patients was 53.1 $\pm$12.5 years. There were 8 males and 21 females, and there were 12 female patients who had no risk factor for atherosclerosis. Twenty six (89.7%) patients showed isolated coronary ostial stenosis without any distal coronary lesion. Result: Anterior approach was used in 28 patients and superior approach was used in one patient. Transsection of the main pulmonary artery was used in one patient. Concomitant CABG was performed in 4 patients because of left anterior descending artery lesions in 3 patients and unstable postoperative hemodynamic status in one patient. Hospital mortality had occurred in one patient (3.4%) and late mortality also in one patient, therefore the overall 5 year survival rate was 91.2$\pm$6.1%. Seventeen coronary angiographies were done in 13 patients (44.8%) postoperatively. Two distal patch stenoses, 1 proximal patch stenosis, and 1 new right coronary ostial lesion were identified and 3 percutaneous interventions and 1 CABG were performed during the follow-up period. The overall 5 year freedom from reintervention rate was 82.4 $\pm$ 8.5%. Aortic regurgitation less than grade 1 had developed postoperatively in 4 patients and one patient showed progression of preexisting aortic regurgitation from grade II to III. Conclusion: Patch angioplasty in left main coronary ostial lesion showed acceptable short-term and long-term results in this study. However, restenosis at the patch anastomosis site and aortic regurgitation should be carefully investigated during the follow-up period.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.328-334
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• 2009

Statement of problem: Pier abutments act as a Class I fulcrum lever system when the teeth are incorporated in a fixed partial denture with rigid connectors. Therefore non-rigid connector incorporated into the fixed partial denture might reduce the stresses created by the leverage. Purpose: The purpose of this study was to evaluate, by means of finite element method, the effects of non-rigid connectors and supporting alveolar bone level on stress distribution for fixed partial dentures with pier abutments. Material and methods: A 2-dimensional finite element model simulating a 5-unit metal ceramic fixed partial denture with a pier abutment with rigid or non-rigid designs, the connector was located at the distal region of the second premolar, was developed. In the model, the lower canine, second premolar, and second molar served as abutments. Four types of alveolar bone condition were employed. One was normal bone condition and others were supporting bone reduced 20% height at one abutment. Two different loading conditions, each 150 N on 1st premolar and 1st molar and 300N on 1st molar, were used. Results: Two types of FPD were displaced apically. The amount of displacement decreased in an almost linear slope away from the loaded point. Non-rigid design tended to cause the higher stresses in supporting bone of premolar and molar abutments and the lower stresses in that of canine than rigid design. Alveolar bone loss increased the stresses in supporting bone of corresponding abutment. Conclusion: Careful evaluation of the retentive capacity of retainers and the periodontal condition of abutments may be required for the prosthetic design of fixed partial denture with a pier abutment.

• Progress in Medical Physics
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• v.12 no.2
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• pp.161-169
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• 2001

For the head and neck radiotherapy, the technique of half beam using independent collimator is very useful to avoid overlapping of fields particularly when the lateral neck fields are placed adjacent to anterior supraclavicular field. Also abutting photon field with electron field is frequently used for the irradiation of posterior neck when tolerable dose on spinal cord has been reached. Using 6 MV X-ray and 9 MeV electron beams of Clinac1800(Varian, USA) linear accelerator, we performed film dosimetry by the X-OMAT V film of Kodak in solid water phantom and the dose distribution at beam center of 2 half beams further examined according to depths(0 cm, 1.5 cm, 3 cm, 5 cm) for single anterior half beam and anterior/posterior half beam. The dose distribution to the junction line between photon and electron fields was also measured. For the single anterior half beam, the absorption doses at 0.3 cm, 0.5 cm and 1 cm distances from beam center were 88%, 93% and 95% of open beam, respectively. In the anterior/posterior half beams, the absorption doses at 0.3 cm, 0.5 cm and 1 cm distances from beam center were 92%, 93% and 95% of open beam, respectively At the junction line between photon and electron fields, hot spot was developed on the side of the photon field and a cold spot was developed on that of the electron field. The hot spot in the photon side was developed at depth 1.5 cm with 7 mm width. The maximum dose of hot spot was increased to 6% of reference doses in the photon field. The cold spot in the electron side was developed at all measured depths(0.5 cm-3 cm) with 1-12.5 mm widths. The decreased dose in the cold spot was 4.5-30% of reference dose in the electron field. With above results, we concluded that when using electron beam or independent jaw for head and neck radiotherapy, the hot and cold dose area should be considered as critical point.

• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.19-31
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• 2002

To investigate the association between the hypertrophy of adenoid and jaw morphology during growth, this paper was based on children patients with experimental adenoids (male-15 subjects at each bone age group, female-15 subjects at each bone group) and comparing them to data taken from a control group (male-15 subjects at each bone age group, female-15 subjects at each bone group) with normal respiratory function. The comparisons between the groups were done at each growth stage using cervical vertebrae maturation index(CVMI) of Hassel. The obtained results were as follows : 1. The differences in craniofacial morphology between experimental group and control group were appeared from CVMI 3 and CVMI 4 (aroud adolescent period) in males, and from CVMI 1 in females. 2. The mandibular position of experimental group was more inferior than control group. The difference appeared at adolescent period(male : at CVMI 4, female : at CVMI 5). 3. Experimental group had greater anterior facial height than control group. This difference seemed a relation with lower anterior facial height. The difference appears at CVMI 3(11.94 ${\pm}$ 1.38 years old, at adolescent period) in male and at CVMI 1 in female. 4. The adenoid size of control male group was increased until CVMI 2(10.58 ${\pm}$ 1.07 years old, just before adolescent growth peak) and then decreased, but in female the adenoid size was decreased from CVMI 1(6.92 ${\pm}$ 0.53 years old).

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.310-322
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• 2000

The objectives of this study were to classify the types of vegetation in Pinus densiflora for. erecta stands. The study sites were located at Sokwang-Ri, Mt. Chungok(1,276m), Uljin, Mt. Kumma(1,017m) and Mt. Eungbong(1,267m). Two hundred thirty releves were classified and explained by phytosociological analysis(the method of ZM schools), and the results were summarized as follows. Pinus densiflora for. erecta stands were classified into Vaccinium koreanum community, Rhododendron micranthum community, Quercus dentata community, Acer pseudosieboldianum community, and Typical community. Quercus dentata community was divided into Festuca ovina group, Robinia pseudoacacia group, and Typical group, and Acer pseudosieboldianum community was divided into Hydrangea serrata for. acuminata group, Disporum smilacinum group, Magnolia sieboldii group, Carpinus laxiflora group, and Typical group, and Typical community was divided into Melampyrum roseum group and Typical group. And some groups were divided into 7 subgroups. Therefore, Pinus densiflora for. erecta stands had total of 16 vegetation units, out of those units, Vaccinium koreanum community distributed all over the studied areas. While Rhododendron micranthum community distributed mainly at Sokwang-Ri and Mt. Chungok. Therefore it was considered to be useful indicator in determining the range of afforestation and natural distribution of Pius densiflora for. erecta stands. The classified vegetation units were investigated by using of coincidence method. The results indicated that Quercus dentata community distributed mainly below 100 meters at the sea level, while other communities distributed above 350 meters at the sea level. According to the correlations between vegetation units and topography, Vaccinium koreanum and Rhododendron micranthum communities distributed mainly above middle slope areas, Quercus dentata community distributed mainly from lower slope to upper slope areas, Acer pseudosieboldianum community distributed mainly between valley and lower slope areas, and Typical community distributed mainly above upper slope areas. According to the correlations between vegetation units and 5 study areas, Quercus dentata community was distributed in the region of Uljin, and other communities were evenly distributed over other studied areas. According to the correlations between the units and aspects, all communities occurred all aspects, but most of the communities tended to be more distributed at south slopes than at north slopes, which meant that the relic stands of Pinus densiflora for. erecta were remained largely as patch phase status at south slopes.