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Search Results: 1 - 10 of 61867 matches for " Jun Seok Lee "
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The Effect of the Variation of the Downstream Region Distance and Butterfly Valve Angle on Flow Characteristics in a 90 Degree Bended Elbow  [PDF]
Se Youl Won, Jae Gon Lee, Jun Seok Yang
Modern Mechanical Engineering (MME) , 2014, DOI: 10.4236/mme.2014.43013
Abstract:
This study presents the numerical evaluation about the impact of flow disturbance near the intrados and extrados regions of the 90 degree bended elbow using CFX for several practical cases where the 90 degree bended upward elbow is located in a proximity to the butterfly valve and the butterfly valve open angle is changed. For the change of a butterfly valve open angle from 60% to 100% and the increase of the distance between a valve and a 90 degree bended elbow, the effect of FAC (Flow-Accelerated Corrosion) in the 90 degree bended elbow may be neglected because the value and distribution of the velocity and shear stress is rapidly decreased comparing with the present status installed in an industry, and the data of 100% valve open (Case 3) and L/D ≈ 5 (Case 4) are very good agreement comparing with the reference data, L/D ≈ 8 (Case 2). The reasons are that flow already maintains a fully developed condition and a steady state in spite of less distance than the reference case, L/D = 8. Therefore, smooth flow fields have approached at a 90 degree bended elbow. Then, the effect of shear stress and vortex is hardly investigated around the intrados area of 90 degree bended elbow.
A New Case of Turner Syndrome with Early Pubertal Development  [PDF]
Seok Ho Yoon, Dong Jun Lee, Son Moon Shin, So Young Yoon, Sung Won Park
International Journal of Clinical Medicine (IJCM) , 2016, DOI: 10.4236/ijcm.2016.75036
Abstract: Turner syndrome (TS) is a relatively common chromosomal disorder caused by complete or partial X monosomy. The most frequently observed karyotype, 45, X, arises more often by loss of the paternal X or Y chromosome in meiosis or in early embryogenesis than by loss of the maternal X chromosome. The main clinical features of TS are short stature, gonadal dysgenesis, and not to undergo pubertal development (e.g. primary amenorrhea). However, a few rare cases of TS have shown precocious puberty. Our case of a 9-year-old girl did not have any TS-specific clinical hallmarks, with the exception of short stature. She visited our clinic because of her pubertal development and short stature. In this report, we highlight the variability that can occur in patients with TS and emphasizes the need to carefully assess unusual growth patterns in any child, regardless of other underlying conditions.
A Hybrid Structure of Dual Stators and a Pneumatic Spring for Resonance Control in an Air Mount  [PDF]
Hyung-Tae Kim, Cheol-Ho Kim, Sung-Bok Kang, Seok-Jun Moon, Gyu-Seop Lee
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.53019
Abstract:

An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to 10 dB.

Rapid decrease of necrotic core after acute myocardial infarction  [PDF]
Jun Ho Lee, Eun-Seok Shin, Shin-Jae Kim, Jong Min Kim, Jung Won Hwang, Hector M. Garcia-Garcia, Patrick W. Serruys
World Journal of Cardiovascular Diseases (WJCD) , 2012, DOI: 10.4236/wjcd.2012.22015
Abstract: It is well known that the increase of necrotic core in previous atherosclerotic coronary artery disease is one of the conditions of vulnerable plaque. However, it is not known how fast necrotic core could decrease in a vulnerable plaque. We had 2 patients who had suffered from acute myocardial infarction and had large amount of necrotic core in their culprit lesions at baseline, which decreased markedly within 7 days. Also, they were clinically stable and asymptomatic over 1 year follow-up. It is first report to show mar-kedly decrease of necrotic core amount within only 7 days in culprit lesions of 2 cases of acute myocardial infarction with angiographically minimal lesions.
Intrauterine midgut volvulus without malrotation: Diagnosis from the coffee bean sign
Jun Seok Park, Seong Jae Cha, Beom Gyu Kim, Yong Seok Kim, Yoo Shin Choi, In Taik Chang, Gwang Jun Kim, Woo Seok Lee, Gi Hyeon Kim
World Journal of Gastroenterology , 2008,
Abstract: Fetal midgut volvulus is quite rare, and most cases are associated with abnormalities of intestinal rotation or fixation. We report a case of midgut volvulus without malrotation, associated with a meconium pellet, during the gestation period. This 2.79 kg, 33-wk infant was born via a spontaneous vaginal delivery caused by preterm labor. Prenatal ultrasound showed dilated bowel loops with the appearance of a ‘coffee bean sign’. This patient had an unusual presentation with a distended abdomen showing skin discoloration. An emergency laparotomy revealed a midgut volvulus and a twisted small bowel, caused by complicated meconium ileus. Such nonspecific prenatal radiological signs and a low index of suspicion of a volvulus during gestation might delay appropriate surgical management and result in ischemic necrosis of the bowel. Preterm labor, specific prenatal sonographic findings (for example, the coffee bean sign) and bluish discoloration of the abdominal wall could suggest intrauterine midgut volvulus requiring prompt surgical intervention.
Cordyceps militaris Extract Protects Human Dermal Fibroblasts against Oxidative Stress-Induced Apoptosis and Premature Senescence
Jun Myoung Park,Jong Seok Lee,Ki Rim Lee,Suk-Jin Ha,Eock Kee Hong
Nutrients , 2014, DOI: 10.3390/nu6093711
Abstract: Oxidative stress induced by reactive oxygen species (ROS) is the major cause of degenerative disorders including aging and disease. In this study, we investigated whether C ordyceps militaris extract (CME) has in vitro protective effects on hydrogen peroxide-induced oxidative stress in human dermal fibroblasts (HDFs). Our results showed that the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of CME was increased in a dose-dependent manner. We found that hydrogen peroxide treatment in HDFs increased ROS generation and cell death as compared with the control. However, CME improved the survival of HDFs against hydrogen peroxide-induced oxidative stress via inhibition of intracellular ROS production. CME treatment inhibited hydrogen peroxide-induced apoptotic cell death and apoptotic nuclear condensation in HDFs. In addition, CME prevented hydrogen peroxide-induced SA-β-gal-positive cells suggesting CME could inhibit oxidative stress-induced premature senescence. Therefore, these results suggest that CME might have protective effects against oxidative stress-induced premature senescence via scavenging ROS.
Initial Responses of Quercus serrata Seedlings and Forest Understory to Experimental Gap Treatments
Cho, Yong-Chan,Jun-Soo Kim,Chang-Seok Lee,Hyun-Je Cho
Journal of Ecology and Field Biology , 2009,
Abstract: Pinus thunbergii plantations in Pohang-si, Gyeongsangbuk-do, Korea, are of low ecological quality,with arrested succession and a high proportion of ruderal species. To improve the quality of the habitat, wecreated canopy gaps (~ 42 m2) and monitored changes in abiotic (light availability, canopy openness) and biotic(survival and growth of seedlings and understory communities) variables in 2007 and 2008 in plots that hadreceived one of five types of treatment: cutting of canopy trees and removal of the understory (CU), cutting ofcanopy trees only (C), girdling of canopy trees and removal of the understory (GU), girdling of canopy trees (G)or control. Each treatment was applied to three replicate plots. Abiotic variables did not significantly differ amongtreatments. Survival rates of target species were slightly lower in the CU, G and control conditions. Based onlogistic regression analysis, the only significant growth factor affecting survival was height growth. Positive effectsof seedling height and leaf area growth on survival were also detected, but did not reach statistical significance.In treatment G, gradual improvement of overstory conditions and mitigation of competition by limitation ofdisturbance to the understory community were likely to have promoted seedling growth. There were no significanteffects of gap treatments on changes in species abundance (cover and richness) and composition of understorybetween the study years. This result implies that the small gaps created in our study may be below the thresholdsize to affect understory growth. However, the results of this study are based on a short-term investigation ofonly two years. Long-term research is strongly recommended to clarify the effects of gap treatment on plantcommunities in afforested areas.
Clinical significance and risk factors of postembolization fever in patients with hepatocellular carcinoma
Chung Hwan Jun,Ho Seok Ki,Hoon Ki Lee,Kang Jin Park
World Journal of Gastroenterology , 2013, DOI: 10.3748/wjg.v19.i2.284
Abstract: AIM: To investigate tumor response and survival in patients with postembolization fever (PEF) and to determine the risk factors for PEF. METHODS: Four hundred forty-three hepatocellular carcinoma (HCC) patients who underwent the first session of transcatheter arterial chemoembolization (TACE) between January 2005 and December 2009 were analyzed retrospectively. PEF was defined as a body temperature greater than 38.0 °C that developed within 3 d of TACE without evidence of infection. The tumor progression-free interval was defined as the interval from the first TACE to the second TACE based on mRECIST criteria. Clinical staging was based on the American Joint Committee on Cancer tumor, node, metastases (TNM) classification of malignant tumors. All patients were admitted before their 1st TACE treatment, and blood samples were obtained from all patients before and after treatment. Clinicoradiological variables and host-related variables were compared between two groups: patients with PEF vs patients without PEF. Additionally, variables related to 20-mo mortality and tumor progression-free survival were analyzed. RESULTS: The study population comprised 370 (85.4%) men and 73 (14.6%) women with a mean age of 62.29 ± 10.35 years. A total of 1836 TACE sessions were conducted in 443 patients, and each patient received between 1 and 27 (mean: 4.14 ± 3.57) TACE sessions. The mean follow-up duration was 22.23 ± 19.6 mo (range: 0-81 mo). PEF developed in 117 patients (26.41%) at the time of the first TACE session. PEF was not associated with 20-mo survival (P = 0.524) or computed tomography (CT) response (P = 0.413) in a univariate analysis. A univariate analysis further indicated that diffuse-type HCC (P = 0.021), large tumor size (≥ 5 cm) (P = 0.046), lipiodol dose (≥ 7 mL, P = 0.001), poor blood glucose control (P = 0.034), alanine aminotransferase (ALT) value after TACE (P = 0.004) and C-reactive protein (CRP) value after TACE (P = 0.036) served as possible risk factors correlated with PEF. The ALT value after TACE (P = 0.021) and lipiodol dose over 7 mL (P = 0.011) were independent risk factors for PEF in the multivariate analysis. For the 20-mo survival, poor blood sugar control (P < 0.001), portal vein thrombosis (P = 0.001), favorable CT response after TACE (P < 0.001), initial aspartate aminotransferase (P = 0.02), initial CRP (P = 0.042), tumor size (P < 0.001), TNM stage (P < 0.001) and lipiodol dose (P < 0.001) were possible risk factors in the univariate analysis. Tumor size (P = 0.03), poor blood sugar control (P = 0.043), and portal vein thrombosis
Origin of the increased velocities of domain wall motions in soft magnetic thin-film nanostripes beyond the velocity-breakdown regime
Sang-Koog Kim,Jun-Young Lee,Youn-Seok Choi,Konstantin Yu. Guslienko,Ki-Suk Lee
Physics , 2008, DOI: 10.1063/1.2968138
Abstract: It is known that oscillatory domain-wall (DW) motions in soft magnetic thin-film nanostripes above the Walker critical field lead to a remarkable reduction in the average DW velocities. In a much-higher-field region beyond the velocity-breakdown regime, however, the DW velocities have been found to increase in response to a further increase of the applied field. We report on the physical origin and detailed mechanism of this unexpected behavior. We associate the mechanism with the serial dynamic processes of the nucleation of vortex-antivortex (V-AV) pairs inside the stripe or at its edges, the non-linear gyrotropic motions of Vs and AVs, and their annihilation process. The present results imply that a two-dimensional soliton model is required for adequate interpretation of DW motions in the linear- and oscillatory-DW-motion regimes as well as in the beyond-velocity-breakdown regime.
Progressive Processing of Continuous Range Queries in Hierarchical Wireless Sensor Networks
Jeong-Hoon Lee,Kyu-Young Whang,Hyo-Sang Lim,Byung-Suk Lee,Jun-Seok Heo
Computer Science , 2009, DOI: 10.1587/transinf.E93.D.1832
Abstract: In this paper, we study the problem of processing continuous range queries in a hierarchical wireless sensor network. Contrasted with the traditional approach of building networks in a "flat" structure using sensor devices of the same capability, the hierarchical approach deploys devices of higher capability in a higher tier, i.e., a tier closer to the server. While query processing in flat sensor networks has been widely studied, the study on query processing in hierarchical sensor networks has been inadequate. In wireless sensor networks, the main costs that should be considered are the energy for sending data and the storage for storing queries. There is a trade-off between these two costs. Based on this, we first propose a progressive processing method that effectively processes a large number of continuous range queries in hierarchical sensor networks. The proposed method uses the query merging technique proposed by Xiang et al. as the basis and additionally considers the trade-off between the two costs. More specifically, it works toward reducing the storage cost at lower-tier nodes by merging more queries, and toward reducing the energy cost at higher-tier nodes by merging fewer queries (thereby reducing "false alarms"). We then present how to build a hierarchical sensor network that is optimal with respect to the weighted sum of the two costs. It allows for a cost-based systematic control of the trade-off based on the relative importance between the storage and energy in a given network environment and application. Experimental results show that the proposed method achieves a near-optimal control between the storage and energy and reduces the cost by 0.989~84.995 times compared with the cost achieved using the flat (i.e., non-hierarchical) setup as in the work by Xiang et al.
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