• Journal of the Korean Geotechnical Society
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• v.34 no.8
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• pp.37-49
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• 2018

Since the observation of ground motions in South Korea, liquefaction manifestation was the first to be observed in Pohang earthquake in 2017 with $M_L$ 5.4. Because liquefaction causes ground settlement and lateral spread damaging in-ground or super structures, various researchers have been analyzing the Pohang liquefaction case history to better understand and predict liquefaction consequence and to prevent future disasters. In prior research at the 2018 EESK conference, a map of Liquefaction Potential Index (LPI), indicating the severity of liquefaction, in Pohang was created and compared with damage observations. The LPI correlated well with the observations, but the severity categorized by LPI range was significantly higher than the actual observations in most regions. The prior LPI map was created evaluating ground motions using the simplified approach. In this research, we perform the effective site response analyses with porewater pressure generation model for the detailed evaluation of liquefaction on the liquefied sites in Pohang. We found that the simplified approach for LPI evaluation can overestimate the severity.

• The Korean Journal of Pharmacology
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• v.20 no.2
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• pp.59-71
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• 1984

To explore the regulatory roles of CNS on the renal function, clonidine, a specific presynaptic ${\alpha}-adrenoceptor$ agonist, was administered into a lateral ventricle of the brain (icv) and the changes of renal function were studies in urethane-anesthetized rabbits. $5{\mu}g/kg$ icv elicited no significant changes in renal function. However, $15{\mu}g/kg$ induced marked natriuresis and kaliuresis for 20 min. Neither RPF nor GFR changed significantly. The fractional sodium reabsorption was significantly reduced, indicating that the renal action was of the tubular origin. Changes of systemic blood pressure were not contributory to the renal action. Yohimbine, a specific antagonist for presynaptic ${\alpha}-adrenoceptor$, when given icv in doses of $100{\mu}g/kg$ 20 min prior to clonidine, completely abolished the renal action of icv clonidine. Yohimbine icv did not produce any significant changes in renal function. Intravenous clonidine, $15{\mu}g/kg$, elicited antidiuresis and decrement of renal function immediately after administration, followed by a slight tendency toward natriuresis, but no natriuresis corresponding to those seen after the icv clonidine were observed, indicating that in the renal action of icv clonidine no direct action is involved. These observations indicate that the central sympathetic tone plays a role in the regulation of renal function in the rabbit.

• Tunnel and Underground Space
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• v.26 no.6
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• pp.484-492
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• 2016

This study is the numerical analysis for the ground stability assessment in ${\bigcirc}{\bigcirc}$mine. The subsidence factors applied to the numerical analysis were as follows. First, the deterioration of the rock mass properties by excavation of the disturbed zone. Second, using the average lateral pressure coefficient of Korea. Third, a study of the mine history. Fourth, the excavating collapsed rock mass in numerical analysis based on the assumption that the rock mass around the goaf was collapsed due to the mining. The developed methods were applied to the cross section (5+10) of the actual subsidence in ${\bigcirc}{\bigcirc}$mine. The feasibility of the numerical analysis methods was confirmed by providing the same results as those of the actual subsidence. Next, the developed methods were applied to the cross section (3+10) that had a high probability of subsidence and the ground stability was evaluated. The analysis results show that the vertical displacement for the 5+10 cross section occurs at a maximum of 46 mm, whereas the analysis results show that the vertical displacement for the 3+10 cross section occurs at a maximum of 7 mm. Hence, it is concluded that the probability for subsidence is low.

• Korean Journal of Applied Biomechanics
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• v.15 no.3
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• pp.161-173
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• 2005

Recently among several tennis techniques forehand stroke has been greatly changed in the aspect of spin, grip and stance. The most fundamental factor among the three factors is the stance which consists of open, square and closed stance. The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle according to open stance patterns during forehand stroke in tennis. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVlEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and racket head angle were defined 1. In three dimensional maximum linear velocity of racket head the X axis showed $11.41{\pm}5.27m/s$ at impact, not the Y axis(horizontal direction) and the z axis(vertical direction) maximum linear velocity of racket head did not show at impact but after impact this will resulted influence upon hitting ball It could be suggest that Y axis velocity of racket head influence on ball direction and z axis velocity influence on ball spin after impact. the stance distance between right foot and left foot was mean $74.2{\pm}11.2m$. 2. The three dimensional anatomical angular displacement of shoulder joint showed most important role in forehand stroke. and is followed by wrist joints, in addition the movement of elbow joints showed least to the stroke. The three dimensional anatomical angular displacement of racket increased flexion/abduction angle until the impact. after impact, The angular displacement of racket changed motion direction as extension/adduction. 3. The three dimensional anatomical angular displacement of trunk in flexion-extension showed extension all around the forehand stroke. The angular displacement of trunk in adduction-abduction showed abduction at the backswing top and adduction around impact. while there is no significant internal-external rotation 4. The three dimensional anatomical angular displacement of hip joint and knee joint increased extension angle after minimum of knee joint angle in the forehand stroke, The three dimensional anatomical angular displacement of ankle joint showed plantar flexion, internal rotation and eversion in forehand stroke. it could be suggest that the plantar pressure of open stance during forehand stroke would be distributed more largely to the fore foot. and lateral side.

• Journal of Trauma and Injury
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• v.21 no.1
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• pp.46-52
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• 2008

Purpose: This study was to evaluate the effect of arterial embolization on survival in patients with pelvic bone fractures and arterial bleeding. Methods: From January 2001 to December 2007, in all, 18 patients with pelvic bone fractures that had been treated with interventional arterial embolization were included in this retrospective study. The Injury Severity Score (ISS), the Revised Trauma Score (RTS), the initial hemodynamic status, the blood gas analysis, blood transfusion data, and mortality were the main outcome measurements. Results: Pelvic bone fractures were classified into lateral compression (LC), antero-posterior compression (APC), vertical shear (VS), and combined (CM) type according to the Young-Burgess classification. The Survivor group included 11 patients (61.1%), and the non-survivor group included 7 patients (38.9%). The mean ages for the survivor and the non-survivor groups were 40.0 and 45.6 years (p=0.517). The types of pelvic bone fractures were LC 11 (61.1%), APC 6 (33.3%), and VS 1 (5.6%): LC 7 (63.6%), and APC 4 (36.4%) in the survivor group and LC 4 (57.1%), APC 2 (28.6%), and VS 1 (14.3%) in the non-survivor group. The internal iliac artery was the predominant injured vessel among both the survivors (n = 5, 45.5%) and the non-survivors (n = 4, 57.1%). No differences in initial blood pressures, ISS, and RTS existed between the two groups, but the arterial pH was lower in the non-survivor group (pH 7.09 (${\pm}0.20$) vs 7.30 (${\pm}0.08$), p=0.018). The number of transfused 24-hour units of packed RBC was greater in the non-survivor group ($24.1{\pm}12.5$ vs $14.4{\pm}6.8$, p=0.046). Conclusion: No differences in initial blood pressure and trauma scores existed between survivors and non-survivors with pelvic bone fractures, who had been treated with arterial embolization, but arterial pH was lower the in non-survivors.

• Journal of Trauma and Injury
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• v.21 no.1
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• pp.22-27
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• 2008

Purpose: Treatment and prognosis in patients with pelvic bone fracture depend on the characteristics of the fracture and the stability of the pelvic ring. The purpose of this study is to analyze the characteristics of and the relationships between fracture patterns, injury mechanisms, clinical courses, and prognoses according to the hemodynamic pattern. Methods: Between January 2004 and September 2006, 89 patients under diagnosis of pelvic bone fracture were retrospectively analyzed on the basis of medical records and radiologic examinations. Patients with confirmed hemorragic shock with a systolic pressure of less than 90 mmHg were defined as the shock group. Young's classification was used to characterize fracture patterns. Factors relating to the clinical manifestation and to treatments such as transfusion and surgery were analytically compared. Results: The mean age of the patients was $48.8{\pm}18.7$, among which 49 (55.1%) were male. The numbers of shock and non-shock patients were 35 (39.3%) and 54 (60.7%) respectively. Eighteen (51.4%) of the shock patient had injuries resulting from pedestrian accidents (p=0.008). According to Young's classification, lateral impact fractures amounted to 20 and 33, front-rear impact fractures to 9 and 20, and multiple fractures to 6 and 1 among the shock and non-shock patients, respectively (p=0.027). Thirty-nine (39) cases in non-shock injuries were conservatively managed while 18 cases in shock injuries were surgically treated. In the shock group, the liver and the kidney were often damaged, as well. Among the shock patients, the average admission period was $7.5{\pm}8.7days$ in intensive care and $55.1{\pm}47.9days$ in total, which were longer than the corresponding numbers of days for the non-shock patients (p<0.05). No deaths occurred in the non-shock group while 5 deaths (14.2%) occurred in the shock group (p=0.007). Conclusion: The factors affecting hemodynamic instability in patients with pelvic bone fracture are injury mechanism, classification of fracture, and associated injuries.

• Journal of Korean Society of Transportation
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• v.30 no.6
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• pp.27-36
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• 2012

In Korea, 28,641 cases of traffic accidents were caused by drunk driving in 2010. These statistics accounted for 12.62% of total number of traffic accidents. Moreover, the percentages of deaths and injuries from them were nearly 15% of those from whole traffic accidents. While police has emphasized enforcement efforts in order to reduce drunk driving, culture generous to drunk driving in addition to the absence of an appropriate intervention system for habitual drunk drivers have contributed to the increasing number of the drunk driving accidents in Korea. This study examined specific behavioral changes in drunk driving by comparing drivers' behavior pattern in non-alcoholic condition to those in alcoholic condition, using a psychomotor test and a driving simulator. In the psychomotor test measuring participants' reactions to the target stimulus, it was revealed that participants' correct responses were decreased, false responses were increased, and no responses also were increased after drinking. Furthermore, in the driving simulator performance after drinking, not only driving speed was faster but also the deviation of an accelerator pedal pressure and of the vehicle's lateral position were much increased. These results indicated that alcohol consumption would impair visio-cognitive ability and deteriorate driving safety. Finally, the implications and limitations of our findings and suggestions for the future research were discussed.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.352-359
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• 2010

Stability of twin tunnels depends on the pillar width and the ground condition. In this study, large scale model tests were conducted for investigating the influence of the pillar width of twin tunnels on their behavior in the regular horizontal jointed rock mass. Jointed rocks was composed of concrete blocks. Pillar width of twin tunnels varied in 0.29D, 0.59D, 0.88D and 1.18D, where D is the tunnel width. During the test, pillar stress, lining stress, tunnel distortion, and ground displacement were measured. Lateral earth pressure coefficient was kept in a constant value 1.0. As a result, it was found that the pillar stress and the displacement of the ground and tunnel were increased by decreasing pillar width. The maximum displacement rate was measured just after the upper excavation in each construction sequence. And the maximum influence position was the right shoulder of the preceeding tunnel at the pillar side. It was also found that for the stability assessment the inner displacement was more critical than the crown displacement. The influence zone was formed at the pillar width 0.59D~0.88D that was smaller than 0.8D~2.0D, which was proposed by experience for a good ground condition. And it would be concluded that horizontal joints could also influence on the stability of the twin tunnels.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.1049-1056
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• 2021

The purpose of this study was to develop a respiratory synchronization device for X-ray (X-RSD) to increase the reproducibility of inspiration when examining the Chest X-ray of a patient who difficulty in breathing coordination. The X-RSD was self-made using an air pressure sensor and air was injected by connecting a ventilator to the mannequin for CPR. At this time, the amount of injected air was quantified using the SkillReporting device. After placing the X-RSD on the chest of the mannequin, the amount of air was tested in 6 steps from 200 to 700 cc by 100 cc increased. For the accuracy evaluation, the sensitivity of X-RSD was measured by repeating a total of 80 measurements, and the sensitivity was 100%, and very precise results were obtained. After that, the images examined while viewing the X-RSD of the chest lateral examination and the images obtained by the blind examination were compared and evaluated. The lung volume of X-RSD was larger than that of the blind test, and the deviation was smaller. Overall, the use of X-RSD can help with chest X-ray examination of patients who have difficulty in cooperating, and it is thought that it will be possible to contribute to the reduction of exposure dose by reducing the repeat rate of general X-ray examinations.

• Asian Spine Journal
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• v.12 no.6
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• pp.1060-1068
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• 2018

Study Design: Retrospective study. Purpose: Lumbar intervertebral disc degeneration is an important cause of low back pain. Overview of Literature: Spinal fusion is often reported to have a good course for adolescent idiopathic scoliosis (AIS). However, many studies have reported that adjacent segment degeneration is accelerated after lumbar spinal fusion. Radiography is a simple method used to evaluate the orientation of the vertebral column. magnetic resonance imaging (MRI) is the method most often used to specifically evaluate intervertebral disc degeneration. The Pfirrmann classification is a well-known method used to evaluate degenerative lumbar disease. After spinal fusion, an increase in stress, excess mobility, increased intra-disc pressure, and posterior displacement of the axis of motion have been observed in the adjacent segments. Methods: we retrospectively secured and analyzed the data of 15 patients (four boys and 11 girls) with AIS who underwent a spinal fusion surgery. We studied the full-length view of the spine (anterior-posterior and lateral) from the X-ray and MRI obtained from all patients before surgery. Postoperatively, another full-length spine X-ray and lumbosacral MRI were obtained from all participants. Then, pelvic tilt, sacral slope, curve correction, and fused and free segments before and after surgery were calculated based on X-ray studies. MRI images were used to estimate the degree to which intervertebral discs were degenerated using Pfirrmann grading system. Pfirrmann grade before and after surgery were compared with Wilcoxon signed rank test. While analyzing the contribution of potential risk factors for the post-spinal fusion Pfirrmann grade of disc degeneration, we used generalized linear models with robust standard error estimates to account for intraclass correlation that may have been present between discs of the same patient. Results: The mean age of the participant was 14 years, and the mean curvature before and after surgery were 67.8 and 23.8, respectively (p<0.05). During the median follow-up of 5 years, the mean degree of the disc degeneration significantly increased in all patients after surgery (p<0.05) with a Pfirrmann grade of 1 and 2.8 in the L2-L3 before and after surgery, respectively. The corresponding figures at L3-L4, L4-L5, and L5-S1 levels were 1.28 and 2.43, 1.07 and 2.35, and 1 and 2.33, respectively. The lower was the number of free discs below the fusion level, the higher was the Pfirrmann grade of degeneration (p<0.001). Conversely, the higher was the number of the discs fused together, the higher was the Pfirrmann grade. Conclusions: we observed that the disc degeneration aggravated after spinal fusion for scoliosis. While the degree of degeneration as measured by Pfirrmann grade was directly correlated by the number of fused segments, it was negatively correlated with the number of discs that remained free below the lowermost level of the fusion.