• Journal of the Korean Geotechnical Society
• /
• v.26 no.7
• /
• pp.117-133
• /
• 2010

A hybrid system of soil-nailing and compression anchor is proposed in this paper; the system is composed of an anchor bar (installed at the tip) with two PC strands and a steel bar. After drilling a hole, installing proposed hybrid systems, and filling the hole with grouting material, prestress is applied to the anchor bar to restrict the deformation at the head and/or to prevent shallow slope failures. However, since the elongation rate of PC strand is much larger than that of steel bar, yield at the steel bar will occur much earlier than at the PC strand. It means that the yield load of the hybrid system will be overestimated if we simply add yield loads of the two - anchor bar and PC strands. It might be needed to try to match the yielding time of the two materials by applying the prestress to the anchor bar. It means that the main purpose of applying prestress to the anchor bar should be two-fold: to restrict the deformation at the nail head; and more importantly, to maximize the design load of the hybrid system by utilizing load transfer mechanism that transfers the prestress applied at the tip to the head through anchor bar. In order to study the load transfer mechanism in a systematic way, in-situ pullout tests were performed with the following conditions: soil-nailing only; hybrid system with the variation of prestress stresses from 0 kN to 196 kN. It was found that the prestress applied to the anchor system will induce the compressive stress to the steel bar; it will result in decrease in the slope of load-displacement curve of the steel bar. Then, the elongation at which the steel bar will reach yield stress might become similar to that of PC strands. By taking advantage of prestress to match elongations at yield, the pullout design load of the hybrid system can be increased up to twice that of the soil-nailing system.

• Restorative Dentistry and Endodontics
• /
• v.24 no.1
• /
• pp.166-179
• /
• 1999

Apical sealing is essential for the success of surgical endodontic treatment. Root-end cavity is apt to be contaminated with moisture or blood, and is not always easy to be dried completely. The purpose of this study was to evaluate the influence of dry methods of retrocavity on the apical seal in endodontic surgery. Apical seal was investigated through the evaluation of apical leakage and adaptation of filling material over the cavity wall. To investigate the influence of various dry methods on the apical leakage, 125 palatal roots of extracted human maxillary molar teeth were used. The clinical crown of each tooth was removed at 10 mm from the root apex using a slow-speed diamond saw and water spray. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. After removing of the coronal 2 mm of filling material, the access cavities were closed with Cavit$^{(R)}$. Two coats of nail polish were applied to the external surface of each root. Apical three millimeters of each root was resected perpendicular to the long axis of the root with a diamond saw. Class I retrograde cavities were prepared with ultrasonic instruments. Retrocavities were washed with physiologic saline solution and dried with various methods or contaminated with human blood. Retrocavities were filled either with IRM, Super EBA or composite resin. All the specimens were immersed in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using one-way ANOVA and Duncan's Multiple Range Test. To evaluate the influence of various dry methods on the adaptation of filling material over the cavity wall, 12 palatal roots of extracted human maxillary molar teeth were used. After all the roots were prepared and filled, and retrograde cavities were made and filled as above, roots were sectioned longitudinally. Filling-dentin interface of cut surfaces were examined by scanning electron microscope. The results were as follows: 1. Cavities dried with paper point or compressed air showed less leakage than those dried with cotton pellet in Super EBA filled cavity (p<0.05). However, there was no difference between paper point- and compressed air-dried cavities. 2. When cavities were dried with compressed air, dentin-bonded composite resin-filled cavities showed less apical leakage than IRM- or Super EBA-filled ones (p<0.05). 3. Regardless of the filling material, cavities contaminated with human blood showed significantly more apical leakage than those dried with compressed air after saline irrigation (p<0.05). 4. Outer half of the cavity showed larger dentin-filling interface gap than inner half did when cavities were filled with IRM or Super EBA. 5. In all the filling material groups, cavities contaminated with blood or dried with cotton pellets only showed larger defects at the base of the cavity than ones dried with paper points or compressed air.

• Korean Journal of Psychosomatic Medicine
• /
• v.8 no.1
• /
• pp.31-45
• /
• 2000

Objectives : The present study was performed to reveal differences between female and male cases of alopecia in their alopecia related variables such as patterns of hair loss, psychiatric characteristics, associate illnesses, and methods of treatment, and to use them as basic materials for proper management and early prevention of the alopecia prone cases. Methods : In order to analysis the gender difference in hair losses, the subjects were divided into two subgroups as the 51 cases of female alopecia and the 42 cases of male alopecia, who had visited to the department of psychiatry consulted from the department of dermatology, Yongsan hopital, ChungAng University, Seoul, Korea, from January 1998 to December 1998. In data analysis, the subjects were statistically assesed by chi-squre test and analysis of varaiance, through SPSS-$PC^+$ 9.0V. Results : 1) Female subjects were more likely showed lower socio-economical level including lower eonomical level, lower educational level, or lower occupational level in their parent's job, were more likely to have larger number of siblings and to have many sisters comparison to the male cases. 2) Female subjects were more likely visited to the department of dermatology, more history of alopecia in their female family members, lesser history of alopecia in their male family members, more loss of hairs in vertex or frontal region of scalp, lesser loss of hairs in occipital region, and lesser nail changes in comparison to the male cases. 3) Female subjects were more suffered from intra-familial conflicts and economical changes, or their introverted personality makeup, lesser likely suffered from changes of business and health changes, and showed lesser conflicts related with poorer adaptaion in their job life. 4) Female subjects were more likely diagnosed as depression or conversion disorders, more frequently complaint anxiety symptoms or depressive symptoms, higher level of anxiety index, lesser complaint somatization or obsessive compulsive symptoms, and lesser diagnosed as anxiety disorder in comparison to the male cases. 5) Female subjects were more likely tended to show personality makeup such as the introverted, the lie, the repressed, or the feminine trends than the male cases. 6) Female subjects were more significantly treated by antianxiety drug such as etizolam and dermatological therapies include tretinoin, and lesser treated by clotiazepam and prednicarbonate in comparison to the male cases. Conclusion : From the facts that The most important factors in developing hair loss in the female subjects in comparison to the male cases seems to be closely correlated with the serious psychopathology such as the presence of mental disorders including depression, the presence of complaining anxiety or depressive symptomatology, the presence of stressful life events such as intrafamilial life changes, and the presence of personality makeup such as the introverted, the lie, the repressed, or the feminine trends, the authors confirmed that dermatologists act as the primary care physician are in a unique position to recognize psychiatric comorbidity and execute meaningful intervention for female patients with the alopecia with psychiatrists.

• Journal of Preventive Medicine and Public Health
• /
• v.29 no.4 s.55
• /
• pp.785-799
• /
• 1996

We investigated the 1,004 workers who worked in a automobile factory to study the epidemiologic characterists of dermatoses due to cutting oils. Among the workers, 667(66.4%) answered the questionaire. They are belong to 5 departments of the factory-the Engine-Work(258 workers), Gasoline engine Assembly(210), Diesel engine Assembly(96), Power train Work(86), Power train Assembly(17). We measured the oil mist concentration in air of the departments and examined the workers who had dermatologic symptoms. The results were follows; 1) Oil mist concentration ; Of all measured points(52),9 points(17.2%) exeeded $5mg/m^3$- the time-weighed PEL-and one department had a upper confidence limit(95%) higher than $5mg/m^3$. 2) Dermatologists examined 213 workers. 172 of them complained any skin symptoms at that time - itching(32.5%), papule(21.6%), scale(15.7%), vesicle(12.5%) in order. The abnormal skin site found by dermatologist were palm(29.3%), finger & nail(24.6%), forearm(16.2%), back of hand(8.4%) in order. 3) As the result of physical examination, we found that 160 workers had skin diseases. Contact dermatitis was the most common; 69 workers had contact dermatitis alone(43.1%), 11 had contact dermatitis with acne(6.9%), 10 had contact dermatitis with folliculitis(6.3%), 1 had contact dermatitis with acne & folliculitis, and 1 had contact dermatitis with abnormal pigmentation. Others were folliculitis(9 workers, 5.6%), acne(8, 5.0%), folliculitis & acne (2, 1.2%), keratosis(1, 0.6%), abnormal pigmentation (1, 0.6%), and non-specific hand eczema (47, 29.3%). 4) The prevalence of any skin diseases was 34.0 pet 100 in cutting oil users, and 13.3 per 100 in non- users. Especially, the prevalence of contact dermatitis was 23.0 per 100 in cutting oil users and 23.0 per 100 in non-users. 5) We tried patch test(standard serise, oil serise, organic solvents) on 49 patients to differentiate allergic contact dermatitis from irritant contact dermatitis and found 20 were positive. 6) In a multivariate analysis(independant=age, tenure, kinds of cutting oil), the risk of skin diseases was higher in the water-based cutting oil user and both oil user than non-user or neat oil user(odds ratio were 2.16 and 2.78, respectively). And the risk of contact dermatitis was much higher at the same groups(odds ratio were 5.16 and 6.82, respectively).