• Journal of Korean Orthopaedic Sports Medicine
• /
• v.10 no.2
• /
• pp.86-93
• /
• 2011

Purpose: The purpose of this study was to analyze the characteristics of the injuries of the national elite Taekwondo players with the best performance in the international championship competition. Materials and Methods: Fifty-two athletes who got the injury in the 2011 Gyeongju World Taekwondo Championship competition were included in this sturdy. 950 members of national team of 146 countries participated in this game, 1,063 matches were performed. We analyzed the characteristics of the injuries such as injury rate by gender, age, weight class, injured region and injury type. Results: Fifty-two athletes of 950 athletes in 1,063 matches got injured and injury rate was 5.47 per 100 participants and 24.47/1,000 athlete-exposures. Injury rate of female athletes was higher than mail, but there was no significant statistical difference (p=0.512). Injury rate of over 30 years old was 17.39 per 100 participants, and injury rate of over 87 kg in male weight class and 68 to 73kg in female weight class were highest than other groups, but there was no significant statistical difference (p=0.838). Overall injury rate of the lower extremity was 13.17/1,000 A-E, higher than upper extremity or head and neck or trunk, but injury rate of the hand was 5.17/1,000 A-E, highest as a specific injured region, followed by the knee, 4.70/1,000 A-E (p=0.714). Injury rate of the sprain was 10.81/1,000 A-E, highest as an injury type, the second most common injury type was the fracture, 5.40/1,000 A-E in men, and was the contusion, 9.63/1,000 A-E in women (p=0.033). As one of the most serious injury, 4 of 8 fractures were occurred in hand. Conclusion: Overall injury rate of the elite Taekwondo players in 2011 Gyeongju World Taekwondo Championship was 5.47 per 100 participants and 24.46 per 1,000 athlete exposures. Although the most common type of injury was the sprain of the knee and ankle, the fractures were more commonly occurred in hand.

• Geophysics and Geophysical Exploration
• /
• v.19 no.1
• /
• pp.1-10
• /
• 2016

The hypocenter distribution of microseismic events generated by hydraulic fracturing for shale gas development provides essential information for understanding characteristics of fracture network. In this study, we evaluate how inaccurate velocity models influence the inversion results of two widely used location programs, hypoellipse and hypoDD, which are developed based on an iterative linear inversion. We assume that 98 stations are densely located inside the circle with a radius of 4 km and 5 artificial hypocenter sets (S0 ~ S4) are located from the center of the network to the south with 1 km interval. Each hypocenter set contains 25 events placed on the plane. To quantify accuracies of the inversion results, we defined 6 parameters: difference between average hypocenters of assumed and inverted locations, $d_1$; ratio of assumed and inverted areas estimated by hypocenters, r; difference between dip of the reference plane and the best fitting plane for determined hypocenters, ${\theta}$; difference between strike of the reference plane and the best fitting plane for determined hypocenters, ${\phi}$; root-mean-square distance between hypocenters and the best fitting plane, $d_2$; root-mean-square error in horizontal direction on the best fitting plane, $d_3$. Synthetic travel times are calculated for the reference model having 1D layered structure and the inaccurate velocity model for the inversion is constructed by using normal distribution with standard deviations of 0.1, 0.2, and 0.3 km/s, respectively, with respect to the reference model. The parameters $d_1$, r, ${\theta}$, and $d_2$ show positive correlation with the level of velocity perturbations, but the others are not sensitive to the perturbations except S4, which is located at the outer boundary of the network. In cases of S0, S1, S2, and S3, hypoellipse and hypoDD provide similar results for $d_1$. However, for other parameters, hypoDD shows much better results and errors of locations can be reduced by about several meters regardless of the level of perturbations. In light of the purpose to understand the characteristics of hydraulic fracturing, $1{\sigma}$ error of velocity structure should be under 0.2 km/s in hypoellipse and 0.3 km/s in hypoDD.

• Geophysics and Geophysical Exploration
• /
• v.10 no.3
• /
• pp.173-182
• /
• 2007

It is well known that manganese nodules enriched with valuable metals are abundantly distributed in the abyssal plain area in the Clarion-Clipperton (C-C) fracture zone of the northeast Pacific. Previous studies using deep-sea camera (DSC) system reported different observations about the relation of seafloor topographic change and nodule abundance, and they were sometimes contradictory. Moreover, proper foundation on the estimation of DSC underwater position, was not introduced clearly. The variability of the mining condition of manganese nodule according to seafloor topography was examined in the Korea Deep Ocean Study (KODOS) area, located in the C-C zone. In this paper, it is suggested that the utilization of deep towing system such as DSC is very useful approach to whom are interested in analysing the distributional characteristics of manganese nodule filed and in selecting promising minable area. To this purpose, nodule abundance and detailed bathymetry were acquired using deep-sea camera system and multi-beam echo sounder, respectively on the seamount free abyssal hill area of southern part ($132^{\circ}10'W$, $9^{\circ}45'N$) in KODOS regime. Some reasonable assumptions were introduced to enhance the accuracy of estimated DSC sampling position. The accuracy in the result of estimated underwater position was verified indirectly through the comparison of measured abundances on the crossing point of neighboring DSC tracks. From the recorded seafloor images, not only nodules and sediments but cracks and cliffs could be also found frequently. The positions of these probable unminable area were calculated by use of the recorded time being encountered with them from the seafloor images of DSC. The results suggest that the unminable areas are mostly distributed on the slope sides and hill tops, where nodule collector can not travel over.

• 한국해양학회지
• /
• v.27 no.3
• /
• pp.210-227
• /
• 1992

KODOS-89 area, the northwestern part of Clarion-Clarion-Clipperton fracture zones in the Northeast Pacific, was surveyed in order to study the occurrence and distribution of manganese nodules. Variations in the nodule characteristics are related mainly to seafloor topography. Nodules from abyssal plain have high Mn/Fe ratio and high Mn, Cu, Ni and Zn concentrations, whereas those from seamount are characterized by low Mn/Fe ratio and high Fe and Co concentrations. These compositional characteristics are attributed to toxic diagnosis and hydrogenesis, respectively. Nodules of the early diegenetic origin tend to accurate crystalline Mn-oxides uniformly within the topmost sediment layers and maintain a regular spheroidal, ellipsoidal to discoidal shape with rough surface textures. On the other hand, those of hydrogenetic origin are characterized by polynucleation, irregualr shape, and smooth surface textures. Nodule abundance is high (avg. 13.4 kg/m$^2$) in seamount area, resulting from ample supply of nucleating materials by auto-fragmentation of older nodules. Nodule abundance in abyssal plain is relatively low (avg. 3.9 kg/m$^2$) and tends to increase southward. This phenomenon results from facilitation of taking seed materials from adjacent seamount and enhancement of the early diagenesis by sufficient supply of organic materials. Nodule abundance is considered to be controlled primarily by seeding effects and secondly by supplies of organic materials.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.27 no.1
• /
• pp.45-53
• /
• 2000

Enamel microabrasion is a means by which superficial enamel discoloration is removed using hydrochloric acid and fine pumice. As enamel microabrasion alone may not be sufficient in cases of deeper discoloration, composite resin restoration is recommended in areas where there is remaining discoloration. The purpose of this study was to investigate the effects of different methods and number of applications of enamel microabrasion on the shear bond strength of composite resin to enamel. Untreated control was designated as group 1. 5-second applications of a mixture of 18% HCl and fine pumice were performed 5 and 10 times on groups 2 and 3, respectively. A commercially available mixture of 10% HCl and abrasives(PREMA) was applied using a 10 : 1 gear reduction handpiece 5 and 10 times on groups 4 and 5, respectively, with each application lasting 20 seconds. After etching with 37% phosphoric acid, composite resin was bonded. Thermocycling was performed and shear bond strength was measured. The following results were obtained : 1. Group 2 showed the highest bond strength$(24.36{\pm}3.34)$, while group 3 showed the lowest$(19.35{\pm}3.43)$, Shear bond strength decreased in the following order: 2>4>5>1>3. 2. Group 2 showed bond strength significantly higher compared to groups 1 and 3(p<0.05). 3. There were no significant differences between groups 2 and 3, which had been microabraded using HCl and pumice, and groups 4 and 5, to which PREMA had been applied, when bond strengths were compared(p>0.05). 4. When modes of fracture were examined, adhesive failure was observed in groups 3 and 4, while cohesive failure was observed in groups 1, 2, 3 and 4. Only mixed failures were found group 5. 5. When viewed using a SEM, groups 2 and 3, which had been microabraded using HCl and pumice, showed surface appearances similar to that of enamel etched with phosphoric acid. Groups 4 and 5, treated with PREMA, exhibited a smooth surface similar to that of group 1. All oops showed similar, typical surface characteristics following phosphoric acid etching.

• The korean journal of orthodontics
• /
• v.25 no.1 s.48
• /
• pp.55-72
• /
• 1995

The purpose of this study is to evaluate the effects of mechanical and thermal fatigue on the shear bond strength(SBS) in orthodontic brackets bonded to human premolars with chemically cured adhesive(Mono-$Lok^2$, Rocky Mountain Orthodontics). Two types of metal brackets (Ormesh, Microloc) and three types of ceramic brackets (Fascination, Starfire, Transcend 2000) were used in this study. The $10^6$ loadcycles of $|7.4{\times}10{^2}sin2{\pi}ft|g{\cdot}cm$ and the 1,000 thermocycles of 15 second dwell time each in $5^{\circ}C\;and\;55^{\circ}C$ baths were acturated as mechanical and thermal fatigue stress, and SBS were measured after each fatigue test. The fracture sites were examined by stereoscope and scanning electron microscope. The results obtained were summarized as follows, 1. In static shear bond test, Fascination brackets showed the maximum SBS($20.78\pm3.45$ MPa) and Microloc brackets showed the minimum SBS($14.88\pm3.10$ MPa). Fascination and Starfire brackets showed significantly greater SBS than Microloc brackets(P<0.05). 2. In mechanical fatigue test, Fascination brackets showed the maximum SBS ($20.19\pm3.45$ MPa) and Starfire brackets showed the minimum SBS($9.10\pm8.33$ MPa). The SBS or Transcend 2000 brackets(P<0.01) and Starfire brackets(P<0.05) significantly decreased after $10^6$ loadcycles. 3. In thermocycling test, Ormesh brackets showed the maximum SBS ($19.36\pm2.76$ MPa) and Starfire brackets showed the minimum SBS($11.94\pm6.86$ MPa). The SBS of Transcend 2000(P<0.01), Microloc and Starfire brackets(P<0.05) significantly decreased after $10^3$ thermocycles. 4. Failure sites of thermocycling groups were similar to those of static groups but after mechanical fatigue test, Ormesh and Transcend 2000 brackets failed at the bracket/resin interface and Microloc brackets failed within adhesive. Facination brackets failed at the enamel/resin interface irrespective of experimental condition.

• Horticultural Science & Technology
• /
• v.30 no.6
• /
• pp.700-708
• /
• 2012

In order to optimize a method to determine the firmness of Chinese cabbage, hardness of midrib tissues was examined based on their chronological order of emergence. Texture measurement using volodkevich bite jaws gave a consistent and highest regression ($r^2=0.85$) between firmness and the order of leaf emergence, while blade set, cylinder probe, and crisp fracture support rig showed a lower coefficient of determination. Thickness of midrib tissue within an individual head from 16 cultivars of Chinese cabbage was positively correlated with the order of emergence, becoming thinner toward inner leaves. Mean thickness of midrib tissue from the head ranged from 7.74 mm for 'CR-shingshing' and 9.28 mm for 'Norangyeorum'. The covariance of leaf thickness within a head was highly cultivar-dependent, ranging from 23.6% for 'Chihili' and 5.8% for 'Bulam'. Firmness of the midrib tissue, defined as maximum peak height per tissue thickness, became higher from outer to inner leaves, showing $2^{nd}$ order of regression. Mean firmness of the midrib tissue from individual head varied from 1.58 N for 'Rangno' to 3.46 N for 'CR-shingshing'. The $10^{th}$ or $11^{th}$ leaf brought the best correlation coefficient (r = 0.81) between firmness of an individual leaf and the mean firmness of the entire leaves in a head, suggesting a reliable and rapid method to estimate the firmness of a head in lieu of examining all leaves in the head. The relationship between firmness of midrib tissue and dry mass ($r=0.70^{**}$) as well as cell wall content ($r=0.58^*$) of the head were positively correlated. Results obtained from the present study suggested that a new method to determine midrib firmness would enable to clarify the relationship between textural quality of fresh Chinese cabbage and their processed product, 'Kimchi'. It will also be important to apply this method to screen textural quality of various genotypes under breeding programs.

• Journal of Conservation Science
• /
• v.33 no.6
• /
• pp.399-416
• /
• 2017

The 'Wat Phou and Associated Ancient Settlements within the Champasak Cultural Landscape' of Laos was designated as a UNESCO World Cultural Heritage in 2001. The uppermost structure of the Sanctuary in Wat Phou has been destroyed and being variably damaged, maintenance is required through scientific and systematic diagnosis. The Sanctuary of Wat Phou was constructed mainly using sandstones and bricks. There are physical damages including fracture, break out, exfoliation and interval as well as biological damages by lichen, mosses and weeds. According to the ultrasonic velocity measurement and property evaluation of the sandstones of the Sanctuary in Wat Phou, weathering index of the eastern side sandstones is 0.10 to 0.74 (mean 0.36), showing MW grade. Southern and northern side sandstones have relatively higher properties with average weathering indices of 0.30 and 0.32. The results of slope analysis of the Sanctuary, indicated that the 4th spot in the southern side has the largest slope of $5^{\circ}W$, seemingly due to the unstable ground around the Sanctuary. Based on the relative level measurement and past drawings, the Sanctuary is verified to have been located on ground with a certain slope rather than flatland. The ground of the southern side is inclined $1.51^{\circ}$ more than that of the northern side, which will affect the structural stability of the temple. The interval width of the selected southern spot is the largest with an average width of 159.5 mm, and the largest width is 328.3 mm at the top, since the width increases above rather than below, seemingly due to the unequal subsidence of the ground. Constant maintenance for conservation is required for the structural stability of the Sanctuary in Wat Phou, which was partly collapsed and has also suffered physical damage.

• Clinical and Experimental Pediatrics
• /
• v.50 no.5
• /
• pp.436-442
• /
• 2007

Purpose : To promote awareness and efforts by pediatricians to identity and prevent child abuse by investigation of characteristics of victim and types of injury caused by abuse. Methods : A retrospective study was performed with 20 patients who had been diagnosed or suspected as child abuse at Hallym University Hospital from January 1999 to December 2005. The medical records, radiologic documents, and social worker's notes were reviewed to investigate age, sex, visiting time, form of abuse, perpetrator, risk factor, and type of injury. Results : The mean age of the subjects was 2.8 years. Fourteen patients were between 0-1 years old, 2 patients between 1-6 years old, 3 patients between 7-12 years old, and 1 case over 13 years old. The ratio of male to female was 1:1. The majority of these patients (70%) visited via emergency department. Eight five percent of these patients reported with physical abuse, 5% psychological abuse, 5% sexual abuse, and 5% neglect respectively. The suspected perpetrator was the biological father in six cases, the biological mother in three cases, the stepmother in two cases, caregiver in one case, relatives in one case and "unknown" in six cases. Bruise and hematoma (80%) were the most common physical findings. Skull fractures were diagnosed in six cases, long bone fractures in two cases, hemoperitoneum in two cases, subdural hemorrhage in 10 cases, epidural hemorrhages in two cases, subarachnoidal hemorrhages in two cases, and retinal hemorrhages in five cases respectively. Seventeen cases required hospitalization and surgical operations performed were in nine cases. Four patients died and three patients had sequalae such as developmental delay and quadriplegia. Conclusion : Child abuse results in high mortality and morbidity in victims. Therefore early recognition and prevention is very important. Pediatricians should always suspect the possibilities of abuse in cases of fracture, intracranial hemorrhage, abdominal injury, or even any injury to the body. We recommend that the clinical investigation of suspicious children should include a full multidisciplinary social assessment, a skeletal survey and CT or MRI.

• Journal of Preventive Medicine and Public Health
• /
• v.10 no.1
• /
• pp.166-175
• /
• 1977

The author have performed an epidemiological study on the accidental deaths at industry from 1970 to 1975, in order to seek for the preventive measures of industrial accident with the under-standing of its cause and characteristics of the accidental deaths. The obtained results were as follows; 1. Total number of deaths for 6 years were 361 (350 males, 11 females). and the mean death rate was 33.8 per 100,000 industrial workers during 6 years. By the highest as 52.9 was in 1974 and the lowest as 13.7 in 1970. By the industry group, the death rate of Electricity, Gas and Water was 149.3, Construction 83.9 and the lowest was Manufacturing as 18.3. 2. Standardized mortality rate of the cases by the age group showed that 20-29 years old group was 43.0, 40-49 years old group 38.1, 30-39 years old group 32.0, and the lowest as 17.9 was under 19 years old group. 3. The cumulative percentage of the cases by years of service showed that under 6 months was 60.4%, under 1 year 72.9%, under 2 years 83.1%. 4. By the month of occurrence, the highest was 15.8% which occurred in August and the lowest was 5.8% in February. The highest as 19.1% was on Friday and the lowest as 11.9% on Monday by the day of a week. 5. By the causes of accident, car accidents was 28.3%, fall accidents 19.1%, accidents by a crash 9.1% in that order. By the location of injury, head was 44.6%, multiple injuries 33.0%, chest 10.5%, and back was the lowest as 1.9%. The distribution of the cases by nature of injury shelved that cerebral contusion and hemorrhage was 39.4%, fracture and dislocation 33.2%, asphyxia 8.0% in that order. 6. The cumulative percentage of the cases by the duration from injury to death showed that the injuried day was 74.2%, within 3 days after injury 88.5%, within 7 days 96.1%. Therefore most of the cases were occurred within 7 days after injury. 7. Byythe daily mean wages, most of the cases as 91.7% were under 2,000 won, and more 4,000 won was 1.6% merely.