• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.755-761
• /
• 2003

Recently, the development of mobile devices demands information storage systems to use micro drive devices and cheap media. These should have several characteristics, for example, the subminiature of size, the robustness of shock, the minimum of cost and power consumption, and the removability of multiple applications. A conventional optical disk drive is more suitable for these specifications than the others. The optical storage system of the new generation to use a blue laser and a high numerical aperture (NA) is the perfect candidate for micro optical disk drives. In this paper, the micro actuator that can be applied to a micro optical disk drive is designed by response surface methodology to use a structural analysis and an electro-magnetic analysis. Based on above results, the coarse actuator and fine actuator are designed and improved from the point of view of the size and the power. Consequently, the designs of a micro actuator are proposed through these courses.

• Journal of The Korean Astronomical Society
• /
• v.28 no.2
• /
• pp.223-243
• /
• 1995

We describe the implementation of a multi-dimensional numerical code to solve the equations for idea! magnetohydrodynamics (MHD) in cylindrical geometry. It is based on an explicit finite difference scheme on an Eulerian grid, called the Total Variation Diminishing (TVD) scheme, which is a second-order-accurate extension of the Roe-type upwind scheme. Multiple spatial dimensions are treated through a Strang-type operator splitting. Curvature and source terms are included in a way to insure the formal accuracy of the code to be second order. The constraint of a divergence-free magnetic field is enforced exactly by adding a correction, which involves solving a Poisson equation. The Fourier Analysis and Cyclic Reduction (FACR) method is employed to solve it. Results from a set of tests show that the code handles flows in cylindrical geometry successfully and resolves strong shocks within two to four computational cells. The advantages and limitations of the code are discussed.

• The Korean Journal of Emergency Medical Services
• /
• v.9 no.1
• /
• pp.89-93
• /
• 2005

Penetrating chest trauma by stab injury may result in massive hemothorax from damage to single or multiple intrathoracic organs such as heart, aorta, internal mammary artery, intercostal artery or pulmonary parenchyme. Prognosis of massive hemothorax necessitating emergency thoracotomy is fatal especially so if there exists concomitant underlying compromise of cardiopulmonary function. A 56 year old man with destroyed left lung due to old pulmonary tuberculosis was stabbed in right parasternal lesion through third intercostal space. Intubation with cardiopulmonary resuscitation and closed thoracostomy were performed to resuscitate from cardiac asystole from hemorrhagic shock and acute respiratory distress. Midsternotomy was made to expose active bleeding foci in right mammary artery, subclavian vein, intercostal artery and anterior segment of right upper lung showing severe bullous change and pleural adhesion. Postoperative care included ventilator support, inotropic instillation and cautious, balance fluid therapy ; successful extubation was done on third postoperative day and patient was discharged on tenth postoperative day without any complication.

• Journal of Chest Surgery
• /
• v.52 no.5
• /
• pp.372-375
• /
• 2019

A 55-year-old man was admitted to the trauma center after a car accident. Cardiac tamponade, traumatic aortic injury, and hemoperitoneum were diagnosed by ultrasonography. The trauma surgeon, cardiac surgeon, and interventional radiologist discussed the prioritization of interventions. Multi-detector computed tomography was carried out first to determine the severity and extent of the injuries, followed by exploratory sternotomy to repair a left auricle rupture. A damage control laparotomy was then performed to control mesenteric bleeding. Lastly, a descending thoracic aorta injury was treated by endovascular stenting. These procedures were performed in the hybrid-angio room. The patient was discharged on postoperative day 135, without complications.

• Structural Engineering and Mechanics
• /
• v.77 no.3
• /
• pp.395-406
• /
• 2021

Near-field underwater explosion (UNDEX) phenomena were investigated by experiments and numerical simulations. The UNDEX experiments were performed in a water tank using a ship-like model. One kilogram of TNT, one of the most widely used military high explosives, was used for the experiments. Numerical simulations were performed under the same conditions as in the experiments using the commercial software LS-DYNA. Underwater pressures, accelerations, velocities, and strains by shock waves were measured at multiple locations. Further, the bubble pulsation period and the whipping deformations of the ship-like model were explored. The experimental results are presented and examined through comparison with the results obtained from widely used empirical equations and numerical simulations.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.32.2-32.2
• /
• 2021

Radio relics, Mpc-size elongated diffuse radio emissions found at galaxy cluster outskirts, are known as the result of shock acceleration during the cluster merger. Theories have claimed that low Mach number shocks are too inefficient to create the observed properties of radio relics. Alternative scenarios such as fossil cosmic ray electrons (CRes) from AGNs are required to explain the observations. However, how exactly the fossil CRes from AGNs can supply the Mpc-size radio relic is still an open question. In this study, we present our recent uGMRT radio observation results of the merging galaxy cluster Abell 514. We found three remarkable AGN jet tails that may have undergone multiple reorientations and extend nearly 800 kpc. Using multi-frequency data, we have performed spectral analysis along the AGN tails and track how the tails lose or gain energy as they propagate in the intracluster medium. We will discuss whether these AGN jets can provide sufficient seed CRes to radio relics.

• Childhood Kidney Diseases
• /
• v.27 no.2
• /
• pp.127-132
• /
• 2023

Cystinuria, a genetically inherited disorder, is a rare cause of kidney stones. It is characterized by impaired transport of cystine and amino acids in the proximal renal tubule and the small intestine. Most patients develop cystine stones throughout their lifetime. Recurrent renal stones need to be extracted by repeated urologic interventions. Treatment options of cystinuria for preventing stone recurrence are limited and poorly tolerated. In this study, we report a pediatric case of cystinuria with a heterozygous SLC3A1 mutation diagnosed by stone analysis, measurement of urine cystine excretion, and genetic analysis. There were recurrent renal stones despite repetitive shock wave lithotripsy and retrograde intrarenal surgery. However, the rate of stone formation seemed to be slower after D-penicillamine was added into adequate hydration and urinary alkalinization.

• Journal of Trauma and Injury
• /
• v.18 no.2
• /
• pp.119-126
• /
• 2005

Background: Blunt thoracic trauma in children has a high morbidity and mortality. In this study, we assessed the significance of the injury pattern, mechanism and initial status in emergency department on severity and prognosis in pediatric blunt thoracic trauma patients. Method: We retrospectively reviewed medical records and chest X-ray and CT images of 111 pediatric blunt thoracic trauma patients from October 2000 to June 2005. Data recorded age, gender, season, injury mechanism, injury pattern, associated injury, length of hospital stay and cause of death. Result: Of all 111 patients, 68 patients were injured by motor vehicle accidents, 30 were falls, 5 were motorcycle accidents, 3 were sports accidents and 5 were miscellaneous. In thoracic trauma, single injury of lung contusion were 35 patients and 32 patients had multiple thoracic injuries. Hospital stay in school age group were longer than preschool age group. The causes of death were brain injury in 9, respiratory distress in 4, and hypovolemic shock in 2 patients. Emergently transfused and mechanically ventilated patients had higher mortality rates than other patients. Patients required emergency operation and patients with multiple thoracic injuries had higher mortality rates. Conclusion: In this study, patients with combined injury, emergency transfusion, mechanical ventilation, emergency operation, multiple injuries in chest X-ray had higher mortality rates. Therefore in these pediatric blunt thoracic trauma patients, accurate initial diagnosis and proper management is required.

• Journal of Trauma and Injury
• /
• v.22 no.2
• /
• pp.254-259
• /
• 2009

Purpose: Pelvic trauma is a serious skeletal injury with high mortality. Especially in cases of severe injury trauma, treatment outcomes depend on early diagnosis and intervention. We expect trauma surgeon to play an important role in the management of severe multiple trauma patients. Methods: A retrospective study was performed on pelvic trauma patients with hemodynamic instability between March 2005 and September 2009. We divided the time period into period I (March 2005~Feburary 2009) and period II (March 2009~September 2009). The trauma surgeon and team started to work from period II. Data were collected regarding demographic characteristics, mechanism of injury, type of pelvic fracture, ISS(injury severity score), treatment modality, transfusion requirement, time to definitive treatment, and mortality. Results: During period I, among 7 hemodynamically unstable patients, 4(57.1%) patients died. However during Period II, only one of 6(16.6%) patients died. The demographic data and injury scores showed no differences between the two time periods, but the time to definitive treatment was very short with trauma team intervention(14.4 hrs vs. 3.9 hrs). Also, the amount of transfusion was less(41.1 U vs. 13.9 U). With arterial embolization, early pelvic external fixation led to less transfusion and made patients more stable. Conclusion: This study demonstrated the importance of the trauma surgeon and the trauma team in cases of hemodynamically unstable pelvic trauma. Even with the same facility and resources, an active trauma team approach can increase the survival of severely injured multiple trauma patients.

• Publications of The Korean Astronomical Society
• /
• v.27 no.4
• /
• pp.243-248
• /
• 2012

Nearby spiral galaxies M101 and M81 are considered to have undergone a galaxy-galaxy interaction. M101 has experienced HI gas infall due to the interaction. With AKARI far-infrared (IR) photometric observations, we found regions with enhanced star forming activity, which are spatially close to regions affected by the interaction. In addition, the relation between the star formation rate (SFR) and the gas content for such regions shows a significant difference from typical spiral arm regions. We discuss possible explanations for star formation processes on a kiloparsec scale and the association with interaction-triggered star formation. We also observed the compact group of galaxies Stephan's Quintet (SQ) with the AKARI Far-infrared Surveyor (FIS). The SQ shows diffuse intergalactic medium (IGM) due to multiple collisions between the member galaxies and the IGM. The intruder galaxy NGC 7318b is currently colliding with the IGM and causes a large-scale shock. The 160 micron image clearly shows the structure along the shock ridge as seen in warm molecular hydrogen line emission and X-ray emission. The far-IR emission from the shocked region comes from the luminous [CII]$158{\mu}m$ line and cold dust (~ 20 K) that coexist with molecular hydrogen gas. Survival of dust grains is indispensable to form molecular hydrogen gas within the collision age (~ 5 Myr). At the stage of the dusty IGM environment, [CII] and $H_2$ lines rather than X-ray emission are powerful cooling channels to release the collision energy.