• Tribology and Lubricants
• /
• v.31 no.5
• /
• pp.221-228
• /
• 2015

It is possible to prevent a piston from contacting the cylinder by changing the shape of the piston or by applying micro-textures, such as micro-grooves or micro-holes, over the piston surface. Usually, the minimum radial clearance reaches its minimum value at the beginning of the suction stroke because the pressure around the piston is low and almost axisymmetric such that the net pressure force on the piston is not sufficiently high to support the piston from touching the cylinder. In this study, we apply a series of saw-tooth-shaped grooves on the piston surface, and numerically investigate the effects of groove depth, groove angle, and the number of grooves with radial clearance variations using a finite difference method. We conduct a dynamic analysis of the piston for various changes in groove geometries to obtain the minimum radial clearance variation for the entire compression cycle. The minimum radial clearance increases while friction loss decreases when we apply the series of saw-tooth-shaped grooves on the piston. In addition, we analyze the impact of the change in the groove shape variable due to changes in radial clearance. Leakage variations are relevant to radial clearance, but have almost no effect on the groove parameters.

• Journal of Preventive Medicine and Public Health
• /
• v.55 no.4
• /
• pp.351-359
• /
• 2022

Objectives: The Regional CardioCerebroVascular Center (RCCVC) project was initiated to improve clinical outcomes for patients with acute myocardial infarction or stroke in non-capital areas of Korea. The purpose of this study was to evaluate the outcomes and issues identified by the Busan RCCVC project in the treatment of ST-segment elevation myocardial infarction (STEMI). Methods: Among the patients who were registered in the Korean Registry of Acute Myocardial Infarction for the RCCVC project between 2007 and 2019, those who underwent percutaneous coronary intervention (PCI) for STEMI at the Busan RCCVC were selected, and their medical data were compared with a historical cohort. Results: In total, 1161 patients were selected for the analysis. Ten years after the implementation of the Busan RCCVC project, the median door-to-balloon time was reduced from 86 (interquartile range [IQR], 64-116) to 54 (IQR, 44-61) minutes, and the median symptom-to-balloon time was reduced from 256 (IQR, 180-407) to 189 (IQR, 118-305) minutes (p<0.001). Inversely, the false-positive PCI team activation rate increased from 0.6% to 21.4% (p<0.001). However, the 1-year cardiovascular death and major adverse cardiac event rates did not change. Even after 10 years, approximately 75% of the patients had a symptom-to-balloon time over 120 minutes, and approximately 50% of the patients underwent inter-hospital transfer for primary PCI. Conclusions: A decade after the implementation of the Busan RCCVC project, although time parameters for early reperfusion therapy for STEMI improved, at the cost of an increased false-positive PCI team activation rate, survival outcomes were unchanged.

• Journal of Korean Biological Nursing Science
• /
• v.18 no.4
• /
• pp.193-202
• /
• 2016

Purpose: The study was to analyze clinical outcomes and risk factors of for complications associated with the hip fracture surgery in the elderly before and after interdisciplinary treatment. Methods: A retrospective method was used to investigate the general and therapeutic characteristics, frequency of complications and clinical outcomes. The subjects of the study were 553 patients who underwent hip fracture surgery from January, 2009 to December, 2014. Results: The interdisciplinary group was older and less likely to walk independently even before the fracture than a usual care group. The incidence of complications was higher in the interdisciplinary group than the usual care group. The prevalence of complications in both groups was 66.5%. Multivariate logistic regression analysis showsed that the risk factors for complications of hip fracture surgery were as follows: advanced age, stroke, Parkinson disease, time interval from emergency room to operation, pre & post ambulatory status, American Society of Anesthesiologists (ASA) classification quality of postop intensive care unit (ICU) care and foley indwelling. Conclusion: This study has implications in that it recognized the necessity for interdisciplinary treatment and provided the basic base data for nursing intervention of the elderly patients who underwent hip fracture surgery.

• Tribology and Lubricants
• /
• v.30 no.5
• /
• pp.278-283
• /
• 2014

Carbon nanotubes (CNTs) are used in various composite materials to enhance electrical, thermal and mechanical properties of composite materials. In this study, we investigate the wear characteristics of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends containing multi-walled carbon nanotubes (MWCNTs). PC/ABS blends are commonly used in many industrial applications such as cellular phones and display cases and MWCNTs have been added to the PC/ABS blends to improve their electromagnetic interference shielding (EMS). We performed wear tests on PC/ABS blends containing MWCNTs under reciprocating linear sliding conditions with chrome steel balls as a counterpart material. The normal loads were 10, 30, 50, 70, 100 N, the sliding speed was 10 mm/s, the stroke length was 15 mm, and the tests lasted 900 s. The MWCNTs included in the PC/ABS blends lower the wear volume and friction coefficient of the composites. We analyzed the wear debris collected from the composites during the tests in terms of the MWCNT concentration using inductively coupled plasma optical emission spectroscopy. The results show that the quantity of MWCNTs in the debris is proportional to the concentration of MWCNTs in the composite, indicating that the exposure of the MWCNTs to environments by wear could be increased with their concentration in the composite.

• The Korea Journal of Herbology
• /
• v.34 no.2
• /
• pp.41-47
• /
• 2019

Objectives : A traditional herbal prescription, Kyung-Ok-Ko (KOK), has long been used in oriental medicine as an invigorant for age-related diseases, such as amnesia and stroke. However, the beneficial value of KOK for immune responses is largely unknown. Based on the above mentioned effects of KOK, other previous reports, and its use in traditional medicine, we hypothesized that KOK displays beneficial effects against methotrexate (MTX)-induced immune suppression. Methods : We investigated the effects of KOK (0.6 g/kg/day, oral (p.o.)) on deteriorated immunity caused by MTX (2 mg/kg/day, p.o.) in an immune suppression mouse model. MTX was fed to mice once a day for 7 days. After the immune responses of the mice deteriorated by MTX treatment, KOK in water was fed to the mice once a day for 14 days. We then measured the expression levels of various cytokines, such as T helper cell (Th1, Th2) cytokines, and the number of immune cells, such as spleen T cells, B cells, and macrophages. Results : The data showed that MTX decreased Th1 profiles (interferon $(IFN)-{\gamma}$, interleukin (IL)-2, IL-12) and the number of immune cells, and increased Th2 profiles (IL-4, IL-5, IL-13), which were normalized significantly by post-administration of KOK. However, there was no significant difference in body-weight gain between MTX- and KOK-treated mice. Conclusion : These results indicate that KOK has immune-enhancing functions and reduces immunotoxicity of MTX, suggesting that supplementation with KOK will improve immune responses clinically and be useful for the prevention of immune-related diseases.

• Journal of the Ergonomics Society of Korea
• /
• v.31 no.2
• /
• pp.379-388
• /
• 2012

Objective: This study developed a new shower carrier prototype to reduce caregivers' muscle burden and to increase use convenience by reflecting the needs of domestic long-term care institutions. Background: In the long-term care institutions, one of the ADL(Activities of Daily Life) factors is bathing/showering. Recently, bath/shower-assisting equipment is actively being introduced in care institutions to reduce the caregivers' care cost, but most of the domestic equipment was designed to imitate foreign products and rarely reflected the needs of care institutions. Method: Based on Korean elderly people's body information, the bed size(length: 1,900mm, width: 650mm) was set-up, and a variable headrest with a newly designed headform was developed to provide the comfort for the elderly and convenience for caregivers. To reduce caregivers' muscle burden on transferring and showering activities, a 3-step column lifting module equipped with dual actuators(lowest/highest levels from the ground: 600/1,100mm, Stroke: 500mm) was developed, and the wheelbase parameter(length: 1,250mm, width: 580mm) was defined securing the turn-over safety of the shower carrier. The drivability tests were performed for the prototype and foreign product, and the male and female subject's muscle activities were measured through the tests. Results: The structural stability of the shower carrier prototype was secured by finite element analysis, and the muscle activities of the subjects through the drivability tests largely decreased in the prototype, compared to the foreign product. Conclusion: In this study, a new shower carrier prototype was developed to possibly reduce caregivers' muscle burden and to increase use convenience based on the needs of long-term care institutions. It was expected that the drivability performance of the prototype could be relatively superior to that of the foreign product. Application: The results obtained from the study can be applied for the optimal development of a shower carrier including other equipment to effectively care for the elderly.

• The Journal of Internal Korean Medicine
• /
• v.30 no.2
• /
• pp.438-449
• /
• 2009

Objectives: Deep vein thrombosis (DVT) is a common complication among stroke patients. The implication of DVT progressing into a fatal pulmonary embolism is one of the main reasons treatment cannot be delayed. However, when there is a contradiction for anticoagulants, such intracranial hemorrhage (ICH), it is difficult to determine the course of treatment. Our team reports a case with both acute DVT and ICH who improved with herbal medicine Hyulbuchuko-tang. Methods : A patient with a variety of thrombosis risk factors (atrial fibrillation, DVT, Cb-inf with intracranial hemorrhage due to thrombolytic complications) showed classic symptoms of DVT (pain, edema, discoloration), disorientation and chest discomfort. The patient was administered Hyulbuchuko-tang three times a day for 24 days without any anticoagulants. Conservative therapy including elastic stocking and leg elevation was co-administered. Laboratory tests and extremity vascular Doppler sonography were carried out 3 times during the treatment period. Results : After our treatment period, both popliteal vein DVT and calf vein DVT were not discovered by sonography, and thrombosis derived factors (eg. D-dimer, fibrinogen) decreased. There was no sign of edema or discoloration after treatment, and the patient no longer complained of leg pain, disorientation or chest discomfort. Conclusion : From these results, we suggest that there is a positive effect of Hyulbuchuko-tang on DVT. Hyulbuchuko-tang should be considered as a treatment option when western medical procedures are unavailable.

• Korean Journal of Clinical Pharmacy
• /
• v.25 no.3
• /
• pp.145-150
• /
• 2015

Objective: Pain is very common in the elderly, so there is a high prevalence of analgesic use among this population. The purpose of this study was to assess patterns of analgesic use and evaluate factors associated with analgesic use in elderly patients. Method: The subjects of this study were patients over 65 years old hospitalized in a teaching hospital located in Chuncheon-si, Korea between January 1, 2014 and March 31, 2014. Data collection regarding analgesic prescriptions and baseline characteristics was conducted using computerized hospital database by medical information team. Logistic regression analysis was used to identify factors related to analgesic use. Results: A total of 2,394 patients were finally included. Among these patients, 700 (29.2%) took analgesics; 521 (74.4%) out of these 700 patients were received opioid analgesics and 179 (25.6%) were received only non-opioid analgesics. The most frequently prescribed opioid analgesic was pethidine (45.7%), and the most frequently prescribed non-opioid analgesic was acetaminophen (44.1%). Fracture was associated with increased odds of opioid analgesic prescriptions (OR = 2.766, 95% CI = 2.019-3.790, p < 0.001) and any analgesic prescriptions (OR = 2.394, 95% CI = 1.766-3.244, p < 0.001). Stroke or cerebral infarction was associated with decreased odds of opioid analgesic prescriptions (OR = 0.636, 95% CI = 0.471-0.858, p = 0.003). Conclusion: A significant proportion of hospitalized elderly patients use analgesics. Health care professionals should consider factors associated with analgesic use in this population to improve pain management.

• Archives of Plastic Surgery
• /
• v.46 no.5
• /
• pp.405-413
• /
• 2019

Background Face transplantation has naturally evolved from reconstructive procedures. However, few institutions perform face transplantations, because it is time-consuming and it is necessary to justify non-vital organ transplantation. We investigated the process of organ donation from brain-dead patients and the possibility of incorporating face transplantation into the donation process. Methods A retrospective review was performed of 1,074 brain-dead patients from January 2015 to December 2016 in Korea. We analyzed the time intervals from admission to brain death decisions (first, second, and final), the causes of brain death, and the state of the transplanted organs. Results The patient base (n=1,074) was composed of 747 males and 327 females. The average period between admission to the first brain death decision was 8.5 days (${\pm}15.3$). The average time intervals between the first brain death decision and medical confirmation using electroencephalography and between the first brain death decision and the final determination of brain death were 16 hours 58 minutes (${\pm}14hours$ 50 minutes) and 22 hours 57 minutes (${\pm}16hours$ 16 minutes), respectively. The most common cause of brain death was cerebral hemorrhage/stroke (42.3%), followed by hypoxia (30.1%), and head trauma (25.2%). Conclusions When face transplantation is performed, the transplantation team has 22 hours 57 minutes on average to prepare after the first brain death decision. The cause of brain death was head trauma in approximately one-fourth of cases. Although head trauma does not always imply facial trauma, surgeons should be aware that the facial tissue may be compromised in such cases.

• Physical Therapy Rehabilitation Science
• /
• v.12 no.3
• /
• pp.207-213
• /
• 2023

Objective: The purpose of this study was to understand the complex anatomical structure and function of the midbrain to better understand the patient's symptoms and plan effective treatment including pharmacological and rehabilitation interventions. Design: A single case study Methods: A 17-year-old girl presented with acute onset of drowsiness, gait disturbance, mutism, and ptosis. Physical examination revealed postural instability, rigidity of all limbs, and limitations in extraocular movement. The brain MRI revealed an isolated acute infarction in the bilateral midbrain. Considering the location of the infarction, the presenting symptoms were the result of an impairment of the dopaminergic pathway in addition to lesions in the nuclei of the oculomotor nerve. Levodopa/carbidopa was prescribed. And the intensive and comprehensive rehabilitation program was done. Results: As a result of the study, through comprehensive intervention, which encompassed assessments such as the manual muscle test, Korean Modified Barthel Index score, and Trail-making test, significant enhancements in the patient's condition were observed. These findings provide evidence supporting the effectiveness of the intervention in promoting the patient's physical functioning and overall well-being. Conclusions: The results of this case highlight the significance of comprehending the intricate anatomical structure and functional aspects of the midbrain, which led us to approach appropriate pharmacological and rehabilitation interventions. Through active communication among the medical team, we were able to establish a therapeutic plan, which demonstrated that effective treatment can be achieved.