• Clean Technology
• /
• v.12 no.1
• /
• pp.11-18
• /
• 2006

In this study, aqueous polyurethane dispersion(PUD) was synthesized using polyhexamethylene carbonate glycol (PHMCG) as soft segment, isophorone diisocyanate (IPDI) and dimethylol propionic acid (DMPA) as hard segment. Also, polyurethane/clay nanocomposites were prepared by adding pristine montmorillonite (PM) and organically modified clays, C15A and C30B into PUD. The degree of clay dispersion in the nanocomposites was investigated using XRD and the physical and thermal properties were examined through UTM and TGA. These results showed that nanocomposites with C15A gave higher physical and thermal properties than those with C30B or PM. As a result, the properties of nanocomposites were observed to vary depending on the types of clay modifiers and clay contents.

• Journal of Korean Neurosurgical Society
• /
• v.57 no.5
• /
• pp.350-358
• /
• 2015

Objective : To evaluate the morphometry of the anterior thalamoperforating arteries (ATPA). Methods : A microanatomical study was performed in 79 specimens from 42 formalin-fixed adult cadaver brains. The origins of the ATPAs were divided into anterior, middle, and posterior segments according to the crowding pattern. The morphometry of the ATPAs, including the premammillary artery (PMA), were examined under a surgical microscope. Results : The anterior and middle segments of the ATPAs arose at mean intervals of $1.75{\pm}1.62$ mm and $5.86{\pm}2.05$ mm from the internal carotid artery (ICA), and the interval between these segments was a mean of $3.17{\pm}1.64$ mm. The posterior segment arose at a mean interval of $2.43{\pm}1.46$ mm from the posterior cerebral artery (PCA), and the interval between the middle and posterior segments was a mean of $3.45{\pm}1.39$ mm. The mean numbers of perforators were $2.66{\pm}1.19$, $3.03{\pm}1.84$, and $1.67{\pm}0.98$ in the anterior, middle, and posterior segments, respectively. The PMA originated from the middle segment in 66% of cases. A perforator-free zone was located >2 mm from the ICA in 30.4% and >2 mm from the PCA in 67.1% of cases. Conclusion : Most perforators arose from the anterior and middle segments, within the anterior two-thirds of the posterior communicating artery (PCoA). The safest perforator-free zone was located closest to the PCA. These anatomical findings may be helpful to verify safety when treating lesions around the PCoA and in the interpeduncular fossa.

• Korean Journal of Applied Biomechanics
• /
• v.22 no.1
• /
• pp.43-53
• /
• 2012

The purpose of this study was to quantitatively examine the biomechanical variables of Fouette turns for expert and beginner ballet dancers and to determine the difference in the variables between the two groups. sixteen female ballet dancers participated in this study. They were divided into an expert group(age, $25.38{\pm}1.92$ years; height, $168.38{\pm}4.66$ cm; mass, $49.63{\pm}4.41$ kg) and a beginner group(age, $20.88{\pm}1.13$ years; height, $161.63{\pm}7.42$ cm; mass, $48.88{\pm}3.64$ kg) depending on their ballet experience. Descriptive data were expressed as mean ${\pm}$ standard deviation (SD) for all variables including the duration, displacement of the center of the body, velocity of the center of the body, angle of the body segments, angular velocity of the body segments, ground reaction force, lower extremity torque, muscle activity, body weight, age, and body mass. An independence t-test was conducted to determine how the following variables differed between the beginners and experts: duration, displacement of the center of the body, velocity of the center of the body, angle of the body segments, angular velocity of the body segments, ground reaction force, lower extremity torque, and muscle activity. All comparisons were made at the p<0.05 significance level. The results show that the experts scored high on the biomechanical variables, although all the variables were not significant. Significant differences were found in the angle of body segments, angular velocity of the body segments, lower extremity torque, and muscle activity(p<0.05). The findings of this study demonstrate that the experts have the required skill to make an improved Fouette turn. The findings may also help ballet dancers to learn and understand the Fouette turn.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.10
• /
• pp.1486-1492
• /
• 2015

The following study carried out the characteristic analysis based on the magnet segment of Interior Permanent Magnet Synchronous Motor(IPMSM) for the urban railway vehicles. IPMSM affects the electromagnetic characteristics through the change in magnetic flux based on the rotor structure, and significantly influences the structural features through the change of pressure. Therefore, satisfied by the demanded traction force of the IPMSM, magnet segment derived three different model types. The 1-segment PM model consisted an undivided permanent magnet. The 2-Bridge model consisted a divided permanent magnet with the application of Bridge. The 3-Bridge model consisted additional dividing with one more Bridge applied. The electromagnetic characteristics of the three models were compared and analyzed along with the structural features regarding the scattering of permanent magnet based on strong centrifugal force from the rotation of the rotor at high speed. In conclusion, the final model with electromagnetic characteristics and structural features most suitable of IPMSM for the urban railway vehicles was derived, and the effectiveness was verified through the characteristic experiments after the production of the derived model.

• Korean Journal of Cleft Lip And Palate
• /
• v.7 no.2
• /
• pp.93-106
• /
• 2004

본 연구의 목적은 편측성 구순구개열 (UCLP) 환자에서 술전 비치조 정형장치 (presurgical nasoalveolar molding appliance, PNAM) 와 구순 봉합수술의 치조골 정형효과를 3차원 (3-D) 분석을 통하여 평가하는 것이다. 연구대상은 16명의 UCLP 환자 (평균 파열부거리: 10.46mm) 이며 PNAM 장치에 의한 치료와 rotation-advancement법에 의한 구순 봉합수술을 받았다 처음 내원시 (평균연령: $37.0{\pm}27.89$ 일), PNAM 치료를 받고 난 후이며 구순봉합수술 1달 전 (평균연령: $119.25{\pm}40.18$ 일), 구순봉합수술 2달 후 (평균연령: $190.81{\pm}42.78$ 일)에 상악의 인상을 채득하였다. 그 후 laser scanning machine (Orapix, Dimennex, Seoul, Korea) 과 3-D view software (3Dxer, Dimennex) 를 사용하여 3-D모형을 제작하였다. 선, 각도, 정중선변이, 거리, 면적 항목을 3-D 모형상에서 계측하고, 각 시기별의 차이를 비교하기 위하여 Wilcoxon signed rank test를 사용하여 분석하였다. PNAM치료 동안과 구순 봉합수술 후에도 치조골 후방부는 안정된 구조물이었다. PNAM치료에 의한 파열부 거리의 감소는 대분절 (greater segment) 의 내측 굴곡 (bending) 에 의하여 발생하였다. 대분절 (greater segment)의 전방 성장은 PNAM치료에 의하여 억제되었으나, 구순 봉합수술 후에 회복되었다. 구순 봉합수술 후에 대분절과 소분절 사이의 전방부 각도의 증가는 구순 반흔 (lip scar) 의 압력에 의한 치조골 정형 효과 때문으로 생각된다. 정중선변이는 PNAM치료에 의하여 개선되었다. PNAM치료 동안과 구순 봉합수술 후에 구개부 (palatal segment) 의 면적은 계속 증가하였다. 치조골 면적과 거리 항목의 증가는 후방부에서 크게 나타났다. 이러한 결과는 PNAM치료에 의한 치조골 정형효과는 주로 전방부에서 발생하며, 치조골의 성장은 구순 봉합수술 후에 후방부에서 주로 발생한다는 것을 의미한다.

• The Journal of Churna Manual Medicine for Spine and Nerves
• /
• v.8 no.1
• /
• pp.39-47
• /
• 2013

Objectives : The purpose of this study is to find out the relationship between hip internal rotation angle and the level of herniation of lumbar intervertebral disc(HIVD) in single-segment. Methods : We investigated 314 patients (158 male, 156 female) who were diagnosed as herniation of lumbar intervertebral disc(HIVD) in single-segment. We measured 314 patients' hip internal rotation angle and analysed the relationship between the hip internal rotation angle and the level of herniation of lumbar intervertebral disc(HIVD). Results : 1. Among 314 cases, the hip internal rotation angle was different between male and female. Hip internal rotation angle of male was mainly limited and that of female was mainly excessive. 2. Among 314 cases, the normal group, defined as patients who have specific range of hip internal rotation angle(male : $35^{\circ}{\pm}10^{\circ}$, female : $45^{\circ}{\pm}10^{\circ}$), tends to be occurred HIVD at L4/5 level. The limited group, defined as patients who have less angle than normal group, the excessive group, defined as patients who have more angle than normal group, and the complex group, defined as patients who have more angle of one leg and less angle of the other leg than normal group, tend to be occurred HIVD at L5/S1 level(p<0.05). Conclusions : In single-segment lumbar HIVD patients, The normal hip internal rotation angle mainly leads to L4/5 HIVD, while the limited and excessive hip internal rotation angle mainly lead to L5/S1 HIVD.

• The Korean Journal of Pain
• /
• v.23 no.2
• /
• pp.131-136
• /
• 2010

Background: We prospectively evaluated the incidence and possible factors causing intramuscular injection during lumbar sympathetic ganglion block and compared the multiple needle technique to the single technique to obtain a profound and complete block effect. Methods: Among 83 patients, 58 patients (group A, n = 27, multiple needle technique and group B, n = 31, single needle technique) were reevaluated for the changes of skin temperature (Ts) and mean segment of longitudinal contrast spread. After injecting the contrast agent, the incidence of psoas muscle injection and the change of Ts was compared between two groups. Results: The incidence of psoas muscle injection was 21.3% (46/216) and it was associated with the level of injection (L2) significantly (${\chi}_2$ = 14.773, P = 0.001). $DT^{post}$ (postblock temperature difference between ipsilateral and contralateral great toe, $4.6{\pm}2.8^{\circ}C$, $1.8{\pm}1.6^{\circ}C$, P < 0.001 for group A and B) and $DT^{net}$ ($DT^{post}$ - $DT^{pre}$, $3.9{\pm}2.7^{\circ}C$, $1.5{\pm}1.5^{\circ}C$, P < 0.001 for group A and B) was significantly higher in group A. The mean segment of longitudinal contrast spread was $8.1{\pm}0.9$ for group A and $3.2{\pm}1.6$ for group B (P < 0.001). Conclusions: The LSGB at the L2 level showed the lowest incidence of psoas muscle injection of contrast. Multiple needle approach showed more significant increase of $DT^{net}$ and $DT^{post}$.

• Korean Journal of Applied Biomechanics
• /
• v.25 no.3
• /
• pp.353-361
• /
• 2015

Objective : The aim of this study was to develop the non-powered horse riding device and was to evaluate the elaborate its applicability throughout static structural and transient structural analysis of the outdoor core strength exercise equipment. Method : Fifteen college students (mass: $69.55{\pm}13.38kg$, height: $1.69{\pm}5.61m$, age: $21.42{\pm}1.83yrs$) rode the powered horse riding device and 14 college students (mass: $71.12{\pm}9.74kg$, height: $1.73{\pm}3.31m$, age: $22.50{\pm}1.47yrs$) rode the non-powered horse riding device for the comparison. All motion capture data was collected at 100 Hz using six infrared cameras and the muscular activities were collected using a Delsys Trigno wireless system. The peak forward/backward lean angle, range of motion anter/posterior and vertical COM(Center of mass) movement of trunk and pelvis segment, and muscle activities of six muscles were compared between the two devices by using independent t-test (p<.05). Results : Several kinematic variables (peak forward-backward lean angle and vertical COM movement of trunk and pelvis segment, range of motion of trunk) significantly different between non-powered and powered horse riding device. The muscle activities of Rectus abdominis and External oblique of abdomen on the non-powered horse riding device were significantly greater than those of the powered device. Conclusion : It was concluded that non-power horse riding device could give the effect of core strength exercise as well as the body motion which can simulate the powered horse riding device.

• Journal of Korean Neurosurgical Society
• /
• v.59 no.4
• /
• pp.374-378
• /
• 2016

Objective : A modified surgical technique of posterior cervical foramintomy called posterior cervical inclinatory foraminotomy (PCIF) was introduced in previous preliminary article. PCIF allows better preservation of facet joint and capsule than conventional techniques. The authors conducted a study to investigate long-term outcomes of PCIF. Methods : We retrospectively reviewed demographic, radiologic, and clinical data from the patients who underwent PCIFs at our institution. Criteria included a minimum of 48 month follow-up and PCIFs for patients with radiculopathy from foraminal stenosis (C2-T1; single or multilevel) with persistent or recurrent root symptoms despite conservative treatment for more than 3 months. Patients who had undergone previous cervical operation were excluded. The visual analogue scale (VAS) score was used for clinical follow-up, and radiologic follow-up was performed to compare the changes of cervical sagittal alignment, focal angle and disc-space height of treated segment. Results : The PCIFs were performed between April 2007 and March 2011 on 46 patients (32 males and 14 females) with a total of 73 levels affected. The average duration of follow-up was 74.4 months. Improvements in radiculopathic pain were seen in 39 patients (84.7%), and VAS score decreased from $6.82{\pm}1.9$ to $2.19{\pm}1.9$. Posterior neck pain also improved in 25 patients (71.4%) among 35 patients, and VAS score decreased from $4.97{\pm}2.0$ to $2.71{\pm}1.9$. The mean disc-space heights of treated segment were $5.41{\pm}1.03mm$ preoperatively and decreased to $5.17{\pm}1.12mm$ postoperatively. No statistically significant changes in cervical sagittal alignment, focal angle were seen during the follow-up period (Cox proportional hazards analysis and Student t-test, p>0.05). Conclusion : The PCIF is highly effective in treating patients with cervical spondylotic radiculopathy, leading to long-lasting relief in pain. Long-term radiologic follow-up showed no significant spinal angular imbalance.

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