• Journal of Chest Surgery
• /
• v.31 no.5
• /
• pp.481-487
• /
• 1998

The surgical management of acute type B dissection is controversial. The complexity of the repair usually requires a period of aortic cross-clamping exceeding 30 minutes, which can cause ischemic injury of the spinal cord. Several forms of distal perfusion have been considered for use to prevent this injury. To determine the safety and efficacy of a graft replacement with cardiopulmonary bypass in reparing acute dissection of descending thoracic aorta, we retrospectively reviewed our surgical experience treating 8 patients who had aortic dissection secondary to atherosclerosis, trauma, and carcinoma invasion. Cardiopulmonary bypass was performed with two aortic cannulas for simultaneous perfusion of the upper and lower body and one venous cannula for draining venous blood from the right atrium or inferior vena cava. Although aortic cross-clamp time was relatively long (average, 117.8 minutes; range, 47 to 180 minutes) in all cases, there was no neurologic deficit immediately after graft replacement for the aortic lesion. Two patients(25%) of relatively old age died on the postoperative 31st and 41st days, respectively, because of delayed postoperative complications, such as pulmonary abscess and adult respiratory distress syndrome. Although any of several maneuvers may be appropriate in managing dissection of the descending aorta, graft replacement with cardiopulmonary bypass during aortic cross-clamping may be a safe and effective method for the treatment of acute dissection of the descending thoracic aorta.

• Journal of Chest Surgery
• /
• v.40 no.2 s.271
• /
• pp.97-102
• /
• 2007

Background: Endovenous laser treatment has recently been introduced as a less invasive technique, with many good results reported, A 980-nm diode laser was used on the great saphenous vein (GSV) occlusions in patients with varicose veins, due to GSV reflux, and the therapeutic effects analyzed. Material and Method: Between September 2003 and February 2006, 238 patients (332 cases) with GSV reflux underwent endovenous laser treatment with a 980-nm diode laser. Operative procedures were simultaneous endovenous laser treatment and ambulatory phlebectomy. The preoperative clinical findings, postoperative complications and postoperative duplex US follow up results at 1 and 3 months were reviewed. Result: Postoperative complications were ecchymosis in almost cases, paresthesia 68 cases (20.5%) and skin burn in 3 cases (0.9%). Follow up duplex US revealed 26 and 10 cases at 1 and 3 months of GSV reflux or partial recanalization, with therapeutic success rates of 91.3 and 87.9%, respectively. Conclusion: The treatment of GSV occlusion with an endovenous laser is less invasive than traditional GSV stripping, but relatively high recanalization was experienced, possibly due to inadequate laser power, laser fiber pullback speed or an extremely dilated GSV. However, continuous attempts will be required to reduce the recanalization after the procedure, with accurate follow up using duplex US.

• Journal of Korean Society of Transportation
• /
• v.22 no.6
• /
• pp.159-173
• /
• 2004

Using a generalized translog multiproduct cost function model, this paper examines economies of scale and scope in the vertically-integrated Korean railway industry. The paper then conceptualizes that the Korea National Railroad (KNR) produces four outputs (passenger-kilometers, ton-kilometers of freight, average length of passenger trips, and average length of freight haul) using three input factors(labor, fuel and maintenance, and rolling stock and capital). Using time series data collected from the KNR's annual records for the years from 1977 to 2002, the simultaneous equation system consisting of a cost function and two input share equatins is estimated with the Zellner's iterative seemingly unrelated regression. The findings show that the cost function corresponding to a non-Cobb-Douglas, non-homothetic, and non-homogeneous production technology adequately represents the KNR's cost structure. On the other hand, the Korean railway industry experiences sizeable overall scale economies, which result from substantial product-specific scale economies associated with passenger-kilometers and freight ton-kilometers and from scope economies associated with their joint production. In addition, the magnitude of economies of scope is influenced largely by the ratio of passenger trips, and has increased over time as the former has increased while the latter has decreased.

• Journal of Korean Society of Transportation
• /
• v.24 no.5 s.91
• /
• pp.109-121
• /
• 2006

The road should be designed in the consistent alignment which the driver can drive safely. Also, proper highway environments in order to maintain optimal operational speeds on highway sections should be provided In design stage, for highway environments, it is essential for an operational speed estimation model to different highway environments. If a method which could evaluate the status of the road safety is developed through this operational speed estimation model, it is possible to provide safe and more comfortable highways to road users. In the study factors to effect on operational speeds are classified into three groups horizontal & vertical alignments and traffic operation characteristic factors. Factors are chosen to effect on operational speeds by using collation analysis as classifications of tangent sections, horizontal curve sections and vertical curve sections. In order to develop operational speed estimation models in express highways, multi-regression analysis has been used in this study using the selected factors. This study has meaning that the developed estimation models for operational speeds and evaluation of degree of safety to horizontal and vortical alignments simultaneous. In order to represent whole area of the country with the developed models, the models should be re-analyzed with vast data related with road alignment factors in the near future.

• 한국가시화정보학회:학술대회논문집
• /
• 2002.11a
• /
• pp.1-6
• /
• 2002

How is the flow in a rotating impeller. About 35 years have passed since one experimentalist rotating with the impeller. of a huge centrifugal blower made the flow measurements using a hot-wire anemometer (Fowler 1968). Optical measurement methods have great advantages over the intrusive methods especially for the flow measurement in a rotating impeller. One is the optical flow visualization (FV) technique (Senoo, et al., 1968) and the other is the application of laser velocimetry (LV) (Hah and Krain, 1990). Particle image velocimetries (PIVs) combine major features of both FV and LV, and are very attractive due to the feasibility of simultaneous and multi-points measurements (Hayami and Aramaki, 1999). A high-pressure-ratio transonic centrifugal compressor with a low-solidity cascade diffuser was tested in a closed loop with HFC134a gas at 18,000rpm (Hayami, 2000). Two kinds of measurement techniques by image processing were applied to visualize a flow in the compressor. One is a velocity field measurement at the inducer of the impeller using a PIV and the other is a pressure field measurement on the side wall of the cascade diffuser using a pressure sensitive paint (PSP) measurement technique. The PIV was successfully applied for visualization of an unsteady behavior of a shock wave based on the instantaneous velocity field measurement (Hayami, et al., 2002b) as well as a phase-averaged velocity vector field with a shock wave over one blade pitch (Hayami, et al., 2002a. b). A violent change in pressure was successfully visualized using a PSP measurement during a surge condition even though there are still some problems to be overcome (Hayami, et al., 2002c). Both PIV and PSP results are discussed in comparison with those of laser-2-focus (L2F) velocimetry and those of semiconductor pressure sensors. Experimental fluid dynamics (EFDs) are still growing up more and more both in hardware and in software. On the other hand, computational fluid dynamics (CFDs) are very attractive to understand the details of flow. A secondary flow on the side wall of the cascade diffuser was visualized based either steady or unsteady CFD calculations (Bonaiuti, et al.,2002). EFD and CFD methods will be combined to a hybrid method being complementary to each other. Measurement techniques by image processing as well as CFD calculations give a huge amount of data. Then, data mining technique will become more important to understand the flow mechanism both for EFD and CFD.

• Toxicological Research
• /
• v.26 no.2
• /
• pp.157-162
• /
• 2010

In this study, we investigated the atmospheric heavy metal concentrations in the particulate matter inside the subway stations of Seoul. In particular, we examined the correlation between the heavy metals and studied the effect of the heavy metals on cell proliferation. In six selected subway stations in Seoul, particulate matter was captured at the platforms and 11 types of heavy metals were analyzed. The results showed that the mean concentration of iron was the highest out of the heavy metals in particulate matter, followed by copper, potassium, calcium, zinc, nickel, sodium, manganese, magnesium, chromium and cadmium in that order. The correlation analysis showed that the correlations between the heavy metals was highest in the following order: (Cu vs Zn), (Ca vs Na), (Ca vs Mn), (Ni vs Cr), (Na vs Mn), (Cr vs Cd), (Zn vs Cd), (Cu vs Cd), (Ni vs Cd), (Cu vs Ni), (K vs Zn), (Cu vs K), (Cu vs Cr), (K vs Cd), (Zn vs Cr), (K vs Ni), (Zn vs Ni), (K vs Cr), and (Fe vs Cu). The correlation coefficient between zinc and copper was 0.937, indicating the highest correlation. Copper, zinc, nickel, chromium and cadmium, which are generated from artificial sources in general, showed correlations with many of the other metals and the correlation coefficients were also relatively high. The effect of the heavy metals on cell proliferation was also investigated in this study. Cultured cell was exposed to 10 mg/l or 100 mg/l of iron, copper, calcium, zinc, nickel, manganese, magnesium, chromium and cadmium for 24 hours. The cell proliferation in all the heavy metal-treated groups was not inhibited at 10 mg/l of the heavy metal concentration. The only exception to this was with the cadmium-treated group which showed a strong cell proliferation inhibition. This study provides the fundamental data for the understanding of simultaneous heavy metal exposure tendency at the time of particulate matter exposure in subway stations and the identification of heavy metal sources. Moreover, this study can be used as the fundamental data for the cell toxicity study of the subway-oriented heavy metal-containing particulate matter.

• Korean Journal of Pharmacognosy
• /
• v.28 no.4
• /
• pp.215-224
• /
• 1997

Gamijiyu-tang (GJT) described originally in the Dong Eui Bo Gam, a traditional reference for oriental medicine in the Korea, has been clinically used for treatment of chronic liver disease. In order to evaluate scientifcally a hepatoprotective effect of GJT in the liver fibrotic disease, the present study investigated how GJT improves a hepatic function in the dimethylnitrosamine (DMN)-treated rat. DMN treatment caused a significant increase of relative liver weight to the body at 28 days after DMN induction. Administration of with a clinical dose decreased significantly the sAST level $(158.8{\pm}7.76\;IU/L)$ elevated by DMN in jection (p<0.01). A similar phenomenon was also observed at change of both Salt and Salt level in the GJT and/or DMN-treated animal (p<0.01, p<0.05, respectively). A remarkable increase of hydroxyproline was observed by treatment of DMN with comparing to the normal rat $(361.9{\pm}7.35\;vs.\;1278.1{\pm}52.9\;{\mu}g/g\;tissue,\;p<0.01)$. This was significantly reduced by a simultaneous treatment of GJT with DMN for 21 days (p<0.05), but not recovered completely to its normal value. In addition. GJT administration ameliorated conspicuously the DMN-induces histopathological changes of liver such as hemorrhage. Cell necrosis and fibrosis. Tak'en together, results described here demonstrated scientifically in first the medicinal efficacy of GJT by using in vivo animal model, indicating that GJT improves the DMN-induced hepatic injury through reducing an excessive accumulation of collagen and histopathological changes. The decreased collagen content may be a pivotal process for GJT to improve hepatic function in the DMN-induced liver fibrosis. The present study suggests that GJT may be useful for and applicable to the treatment of hepatic fibrosis in chronic liver disease.

• Journal of Life Science
• /
• v.26 no.2
• /
• pp.247-252
• /
• 2016

Cultivated wild ginseng is a widely used dietary supplement and medicinal herb. The aim of this study was to optimize the ginseng using high performance liquid chromatography (HPLC)- charged aerosol detection (CAD) for ginsenoside analysis. CAD measures the physical property of an analyte and responds to almost all non-volatile species, independent of their nature, spectral properties, or particle size. It has become widely employed in pharmaceutical analysis. The cultivated wild ginseng extracts were analyzed for compositions of ginsenosides Rb1, Rd, Rg1, Rf, Re, and Rh1. The optimal analysis condition was set up from an experiment using a gradient. Ten grams of cultivated wild ginseng were extracted with 95% EtOH 100 ml for 24 hr at 80℃. The contents of the 6six major ginsenosides in the cultivated wild ginseng extract were Rb1 (5.48±0.12 mg/g), Rd (5.33±0.14 mg/g), Rg1 (12.80± 0.05 mg/g), Rf (19.08±0.68 mg/g), Re (19.87±0.05 mg/g), and Rh1 (16.47±0.16 mg/g), respectively. HPLC showed that the protopanaxatriol group (Rg1, Rf, Re, Rh1) had more content than the protopanaxadiol group (Rb1, Rd) in cultivated wild ginseng extract. In summary, the ginsenosides were identified with HPLC-CAD analysis, and their presence and quantity imply the importance of quality control, as well as the pharmacological activity of the ginseng root.

• Journal of Life Science
• /
• v.22 no.3
• /
• pp.428-436
• /
• 2012

Protein phosphorylation is a universal mechanism that regulates cellular activities. The brassinosteroid (BR) signal transduction pathway is a relay of phosphorylation and dephosphorylation cascades. It starts with the BR-induced activation of the membrane receptor kinase brassinosteroid insensitive 1 (BRI1), resulting in the dephosphorylation of transcription factors such as BZR1/BES2 and BZR2/BES1 followed by BR-induced gene expression. Brassinosteroid signal transduction research has progressed rapidly by identifying the phosphorylation/dephosphorylation site(s) of the BR-regulated kinase and phosphatase substrates with a simultaneous pursuit of mutant phenotypes. Autophosphorylation, transphosphorylation, and serine/threonine and tyrosine phosphorylation of the receptor protein kinases BRI1 and BRI1-associated kinase (BAK1) have increased the understanding of the regulatory role of those kinases during physiological and developmental processes in plants. The phosphorylation event initiated by BR is also found in the regulation of receptor-mediated endocytosis and the subsequent degradation of the receptor. However, the basic molecular links of the BR signal transduction pathway are not well understood regarding this phosphorylation/dephosphorylation event. This review summarizes the current state of BR signal transduction research to uncover the phosphorylation/dephosphorylation networks and suggests directions for future research on steroid signal transduction to gain a more comprehensive understanding of the process.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.8
• /
• pp.771-782
• /
• 2017

This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.