• Journal of the Korean Society for Precision Engineering
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• v.6 no.1
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• pp.45-51
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• 1989

In metal cutting various types of chips are produced in consequence of cutting conditions. According to the type of chips the cutting mechanism is to be changed. Most of the cutting theory is based on the continuous chip because of its convenient analysis, but the occurrence of the saw-toothed chip depends upon the workpiece and/or the cutting conditions, one of which is titanium alloy used widely. Nowadays titanium alloys are used widely with the rapid development of aerospace structural engineering application, whereas the theory of cutting mechanism has not been established yet, and the formatting process has not been understood satisfactorily, either. Unfortunately several misconceptions, conflicting statements and statements needing further clarifi- cation are also found. In this paper an attempt is made to clarify the formation process of saw-toothed chips which are to be produced during the orthogonal cutting process of titanium alloys. They were machined at low speed to avoid the rapid tool wear. We observed the SEM-photographs of chips taken at the quick-st- opping device. It is hoped that a rational model of the mechanics of cyclic chip formation can be developed. The results obtained are as follows. 1. When a saw- toothed chip is formed, the shear band begins at the primary shear zone and trans- fers to the free surface, so that a segment is produced and it is completed by upsetting between the formatting segment and the formatted segment. 2. As the rake angle or the clearance angle increases in the machining of the titanium alloy, the chip approaches to that of the continous type. 3. When the rake angle and the clearance angle are increased the shear energy and the unit friction energy decrease, which shows the same aspect as that of the continuous chip.

• The korean journal of orthodontics
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• v.39 no.1
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• pp.54-65
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• 2009

This paper describes the case of a 50-year-old female with a Class II malocclusion who presented with severe bimaxillary protrusion and generalized alveolar bone loss due to adult periodontitis. The treatment plan consisted of extracting both upper and lower first premolars and periodontal treatment. Anterior segmental osteotomy(ASO) of the mandible and upper anterior segment retraction using compression osteogenesis after peri-segmental corticotomy(Speedy orthodontics) was performed. Correct overbite and overjet, facial balance, and improvement of lip protrusion were obtained. However, a slight root resorption tendency was observed on the lower anterior dentition. The active treatment period was 9 months and the results were stable for 27 months after debonding. This new type of treatment mechanics can be an effective alternative to orthognathic surgery.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.100-105
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• 2017

Objectives: Localization of the mandibular canal (MC) and measurement of the height and width of the available alveolar bone at the proposed implant site in the posterior segment of the mandible using cone-beam computed tomography (CBCT) in patients with a single missing tooth. Materials and Methods: A cross-sectional study was performed where CBCT scans of the patients with a single missing tooth in the posterior segment of the mandible-premolar, I (1st) molar, and II (2nd) molar were used. The scans were assessed using OnDemand3D software (version 1.0; CyberMed Inc., Seoul, Korea) for localization of the MC asnd remaining alveolar bone both vertically (from the superior position of the MC to the crest of the alveolar ridge) and horizontally (buccolingual, 3 mm below the crest of the alveolar ridge). The findings were statistically analyzed using independent t-test. Results: A total of 120 mandibular sites (40 sites for each of the three missing premolar, I molar, and II molar) from 91 CBCT scans were analyzed. The average heights (from the alveolar crest to the superior margin of the MC) at the premolar, I molar, and II molar areas were $15.19{\pm}2.12mm$, $14.53{\pm}2.34mm$, and $14.21{\pm}2.23mm$, respectively. The average widths, measured 3 mm below the crest of the alveolar ridge, at the premolar, I molar, and II molar areas were $6.22{\pm}1.96mm$, $6.51{\pm}1.75mm$, and $7.60{\pm}2.08mm$, respectively. There was no statistically significant difference between males and females regarding the vertical and horizontal measurements of the alveolar ridges. Conclusion: In the study, the measurements were averaged separately for each of the single missing teeth (premolar, I molar, or II molar), giving more accurate information for dental implant placement.

• Korean journal of applied entomology
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• v.27 no.2
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• pp.94-102
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• 1988

Studies were carried out to describe the structure and distribution of various sensilla on the antenna and mouthparts of the Oriental tobacco bud worm (H. assulta) larvae by light and scanning electron microscopy. The larval antenna has 3 segments. The second segment has 2 hairs and 3 pegs, while the third segment shows 3 regular pegs and a segmented peg (styloconicum type). Each mandible bears 2 aporous hairs on the lateral surface. The labrum bears 12 aporous hairs on its external surface. and 6 aporous hairs, 4 coeloconica-like sensilla and 2 campaniformia-like sensilla on its epipharynx. The stipes has 3 hairs, and the galea has 3 pegs. 2 papillae and 2 domes. The maxillary palpus has only a digitiform sensillum on its 1st segment but 11 sensilla of 4 different types on its 2nd segment. Maxillary sensilla represent almost 70% of total number of larval sensilla on the mouthparts. Labial pal pus has a single segment bearing a large segmented uniporous peg and a small peg. Finally their possible fun¬ctions were suggested.

• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.271-280
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• 2011

Heart Rate Variability (HRV) analysis is a convenient tool to assess Myocardial Ischemia (MI). The analysis methods of HRV can be divided into time domain and frequency domain analysis. This paper uses wavelet transform as frequency domain analysis in contrast to time domain analysis in short term HRV analysis. ST-T and normal episodes are collected from the European ST-T database and the MIT-BIH Normal Sinus Rhythm database, respectively. An episode can be divided into several segments, each of which is formed by 32 successive RR intervals. Eighteen HRV features are extracted from each segment by the time and frequency domain analysis. To diagnose MI, the Neural Network with Weighted Fuzzy Membership functions (NEWFM) is used with the extracted 18 features. The results show that the average accuracy from time and frequency domain features is 75.29% and 80.93%, respectively.

• Archives of Craniofacial Surgery
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• v.19 no.4
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• pp.304-308
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• 2018

Replantation using microvascular anastomosis is considered to be the optimal method in treating the amputated ear in terms of resulting color, texture, and shape. Only a few cases of ear replantation have been reported because it is anatomically difficult to identify suitable vessels for anastomosis. We successfully replanted the amputated helical rim of the ear using single arterial anastomosis. A 37-year-old man had his helical rim amputated by a human bite. The amputee was about $4{\times}1cm$ in dimension, composed of skin and soft tissue including auricular cartilage. Replantation was performed anastomosing a small artery of the amputee with a terminal branch of the posterior auricular artery. After replantation, intravenous heparinization was performed and prostaglandin E1 and aspirin were administered. Venous congestion was decompressed by stab incisions applied with heparin solution soaked gauze. Venous congestion of the amputee slowly began to resolve at 4 days after the operation. The amputated segment of the helical rim survived completely with good aesthetic shape and color. The authors propose that performing microvascular anastomosis should be attempted especially if it is possible to detect vessels on cut surfaces of ear amputee and stump. Proper postoperative care for venous congestion, arterial insufficiency, and infection should be followed for amputee survival.

• Journal of Korean Neurosurgical Society
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• v.47 no.5
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• pp.352-357
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• 2010

Objective : This retrospective study was performed to evaluate the clinical and radiological results of anterior lumbar interbody fusion (ALIF) using two different stand-alone cages in the treatment of lumbar intervertebral foraminal stenosis (IFS). Methods : A total of 28 patients who underwent ALIF at L5-S1 using stand-alone cage were studied [Stabilis$^{(R)}$ (Stryker, Kalamazoo, MI, USA); 13, SynFix-LR$^{(R)}$ (Synthes Bettlach, Switzerland); 15]. Mean follow-up period was 27.3 ${\pm}$ 4.9 months. Visual analogue pain scale (VAS) and Oswestry disability index (ODI) were assessed. Radiologically, the change of disc height, intervertebral foraminal (IVF) height and width at the operated segment were measured, and fusion status was defined. Results : Final mean VAS (back and leg) and ODI scores were significantly decreased from preoperative values (5.6 ${\pm}$ 2.3 ${\rightarrow}$ 2.3 ${\pm}$ 2.2, 6.3 ${\pm}$ 3.2 ${\rightarrow}$1.6 ${\pm}$ 1.6, and 53.7 ${\pm}$ 18.6 ${\rightarrow}$ 28.3 ${\pm}$ 13.1, respectively), which were not different between the two devices groups. In Stabilis$^{(R)}$ group, postoperative immediately increased disc and IVF heights (10.09 ${\pm}$ 4.15 mm ${\rightarrow}$ 14.99 ${\pm}$ 1.73 mm, 13.00 ${\pm}$ 2.44 mm ${\rightarrow}$ 16.28 ${\pm}$ 2.23 mm, respectively) were gradually decreased, and finally returned to preoperative value (11.29 ${\pm}$ 1.67 mm, 13.59 ${\pm}$ 2.01 mm, respectively). In SynFix-LR$^{(R)}$ group, immediately increased disc and IVF heights (9.60 ${\pm}$ 2.82 mm ${\rightarrow}$ 15.61 ${\pm}$ 0.62 mm, 14.01 ${\pm}$ 2.53 mm ${\rightarrow}$ 21.27 ${\pm}$ 1.93 mm, respectively) were maintained until the last follow up (13.72 ${\pm}$ 1.21 mm, 17.87 ${\pm}$ 2.02 mm, respectively). The changes of IVF width of each group was minimal pre- and postoperatively. Solid arthrodesis was observed in 11 patients in Stabilis group (11/13, 84.6%) and 13 in SynFix-LR$^{(R)}$ group (13/15, 86.7%). Conclusion : ALIF using stand-alone cage could assure good clinical results in the treatment of symptomatic lumbar IFS in the mid-term follow up. A degree of subsidence at the operated segment was different depending on the device type, which was higher in Stabilis$^{(R)}$ group.

• Korean Journal of Radiology
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• v.24 no.9
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• pp.827-837
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• 2023

Objective: To investigate the predictive value of radiomics features based on cardiac magnetic resonance (CMR) cine images for left ventricular adverse remodeling (LVAR) after acute ST-segment elevation myocardial infarction (STEMI). Materials and Methods: We conducted a retrospective, single-center, cohort study involving 244 patients (random-split into 170 and 74 for training and testing, respectively) having an acute STEMI (88.5% males, 57.0 ± 10.3 years of age) who underwent CMR examination at one week and six months after percutaneous coronary intervention. LVAR was defined as a 20% increase in left ventricular end-diastolic volume 6 months after acute STEMI. Radiomics features were extracted from the oneweek CMR cine images using the least absolute shrinkage and selection operator regression (LASSO) analysis. The predictive performance of the selected features was evaluated using receiver operating characteristic curve analysis and the area under the curve (AUC). Results: Nine radiomics features with non-zero coefficients were included in the LASSO regression of the radiomics score (RAD score). Infarct size (odds ratio [OR]: 1.04 (1.00-1.07); P = 0.031) and RAD score (OR: 3.43 (2.34-5.28); P < 0.001) were independent predictors of LVAR. The RAD score predicted LVAR, with an AUC (95% confidence interval [CI]) of 0.82 (0.75-0.89) in the training set and 0.75 (0.62-0.89) in the testing set. Combining the RAD score with infarct size yielded favorable performance in predicting LVAR, with an AUC of 0.84 (0.72-0.95). Moreover, the addition of the RAD score to the left ventricular ejection fraction (LVEF) significantly increased the AUC from 0.68 (0.52-0.84) to 0.82 (0.70-0.93) (P = 0.018), which was also comparable to the prediction provided by the combined microvascular obstruction, infarct size, and LVEF with an AUC of 0.79 (0.65-0.94) (P = 0.727). Conclusion: Radiomics analysis using non-contrast cine CMR can predict LVAR after STEMI independently and incrementally to LVEF and may provide an alternative to traditional CMR parameters.

• Biomedical Science Letters
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• v.21 no.4
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• pp.198-207
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• 2015

ST-segment elevation myocardial infarction (STEMI) and chronic total occlusion (CTO) of coronary artery are well-known atherosclerotic vascular diseases. However, the difference of intima-media thickness and plaque characteristics of carotid arteries between STEMI and CTO patients were not directly compared in previous studies. Medical records of a total of 158 (101 STEMI, 57 CTO) patients, who underwent carotid artery ultrasonography, were selected for the analysis. The baseline characteristics, ultrasonography findings, and clinical outcomes of the two groups were compared. The prevalence of hypertension, diabetes mellitus, and dyslipidemia was significantly higher in CTO patients. Carotid intima-media thickness ($0.97{\pm}0.13$ vs. $0.78{\pm}0.17cm$, P < 0.0001) and number of plaques ($2.2{\pm}1.0$ vs. $1.7{\pm}1.2$, P < 0.0001) were greater in CTO than STEMI patients. Multiple (${\geq}3$) or echogenic plaques were more frequently observed in CTO patients. During the median follow-up duration of 27 months, major adverse cardiovascular events occurred in 31% of CTO and 14% of STEMI patients (P = 0.008). We found that, compared with STEMI, CTO patients have higher burden of carotid artery atherosclerosis associated with more comorbid diseases and poor clinical outcomes.

• ALGAE
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• v.22 no.2
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• pp.107-116
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• 2007

Annual growth segments of Ascophyllum nodosum (L.) Le Jolis (Fucales, Fucaceae) are denoted by air bladders that form each spring. By examining annual growth segments, it may be possible to infer information about the physical conditions during the growth period; however, it is uncertain whether the annual segments will expand in size after the initial growth. We examined A. nodosum segments from three populations in Nova Scotia, and statistically evaluated whether the annual growth (length, mass, and maximum diameter) of segments was independent of the age of the frond, whether the segments increased in size after the initial growth, and whether the segment lengths were correlated with mean water temperatures and mean air temperatures when the segments were formed. We found that the growth in length of A. nodosum is dependent on the age of the frond, but frond age explained less than 12 % of the overall variation in length. However, the mass and maximum diameter of segments were independent of the age of the frond. Differences occurred between the lengths of segments formed in different years, but there was no significant correlation with regional mean water or air temperatures. This study indicates that the length of A. nodosum segments may be an indicator of the annual physical characteristics of a site, but future studies are needed to identify which factors have the strongest influence on growth patterns.