• Wind and Structures
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• v.28 no.2
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• pp.71-87
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• 2019

The yaw and interference effects of blades affect aerodynamic performance of large wind turbine system significantly, thus influencing wind-induced response and stability performance of the tower-blade system. In this study, the 5MW wind turbine which was developed by Nanjing University of Aeronautics and Astronautics (NUAA) was chosen as the research object. Large eddy simulation on flow field and aerodynamics of its wind turbine system with different yaw angles($0^{\circ}$, $5^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ and $45^{\circ}$) under the most unfavorable blade position was carried out. Results were compared with codes and measurement results at home and abroad, which verified validity of large eddy simulation. On this basis, effects of yaw angle on average wind pressure, fluctuating wind pressure, lift coefficient, resistance coefficient,streaming and wake characteristics on different interference zone of tower of wind turbine were analyzed. Next, the blade-cabin-tower-foundation integrated coupling model of the large wind turbine was constructed based on finite element method. Dynamic characteristics, wind-induced response and stability performance of the wind turbine structural system under different yaw angle were analyzed systematically. Research results demonstrate that with the increase of yaw angle, the maximum negative pressure and extreme negative pressure of the significant interference zone of the tower present a V-shaped variation trend, whereas the layer resistance coefficient increases gradually. By contrast, the maximum negative pressure, extreme negative pressure and layer resistance coefficient of the non-interference zone remain basically same. Effects of streaming and wake weaken gradually. When the yaw angle increases to $45^{\circ}$, aerodynamic force of the tower is close with that when there's no blade yaw and interference. As the height of significant interference zone increases, layer resistance coefficient decreases firstly and then increases under different yaw angles. Maximum means and mean square error (MSE) of radial displacement under different yaw angles all occur at circumferential $0^{\circ}$ and $180^{\circ}$ of the tower. The maximum bending moment at tower bottom is at circumferential $20^{\circ}$. When the yaw angle is $0^{\circ}$, the maximum downwind displacement responses of different blades are higher than 2.7 m. With the increase of yaw angle, MSEs of radial displacement at tower top, downwind displacement of blades, internal force at blade roots all decrease gradually, while the critical wind speed decreases firstly and then increases and finally decreases. The comprehensive analysis shows that the worst aerodynamic performance and wind-induced response of the wind turbine system are achieved when the yaw angle is $0^{\circ}$, whereas the worst stability performance and ultimate bearing capacity are achieved when the yaw angle is $45^{\circ}$.

• Environmental and Resource Economics Review
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• v.28 no.3
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• pp.355-383
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• 2019

This study is to investigate whether averting costs for wearing $anti-PM_{10}$ masks and using air purifiers at home to reduce exposure from $PM_{10}$ are influenced by subjective risk perceptions and/or objective $PM_{10}$ concentration levels, whose estimates will be used to measure the willingness to pay for $PM_{10}$ risk reduction. An empirical analysis was conducted on a sample of 1,224 respondents who participated in the web-based survey in the late October of 2017. As we reflect the potential endogeniety bias in the estimation of averting cost functions of using air purifiers, the coefficients of risk perception were differed by 6~7 times. Respondents. subjective risk perceptions were influenced by individuals' knowledge, attitudes and demographic variables, as well as the levels of $PM_{10}$ concentrations in their residential region. The marginal willingness to pay for risk reductions at the mean levels of their risk perceptions were measured at 1,000 won per month from wearing $anti-PM_{10}$ masks and 6,000 won for using air purifiers respectively.

• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.69-74
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• 2019

The purpose of this study is to compare the efficiency of bacteria removal of three different types of hand washing methods. This study performed a convenient sampling of 30 volunteers in cross-over design. The study divided the 30 volunteers into three random groups. The three groups were asked to use antiseptic soap, alcohol-based hand disinfectant, and disposable wet wipes respectively. The result of the study showed that mean log reduction values after each had washing method were $-0.45({\pm}0.69)$ with antiseptic soap and water, $-1.19({\pm}0.52)$ with alcohol-based hand disinfectant and $-0.75({\pm}0.58)$ with disposable wet wipes. The difference was statistically significant when using alcohol-based hand disinfectant compared to the other two methods (p=0.000). According to this study, alcohol-based hand disinfectant was the most effective product based on bacteria removal for hand washing. Advantages of using alcohol-based hand disinfectant are that it is cost-effective and easy to buy, also eco-friendly. Therefore, to prevent infectious disease, providing alcohol-based hand disinfectant to every corner of the community will be very helpful.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.787-797
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• 2022

The purpose of this study was to confirm the reduction of pain and symptom relief of Parkinson's disease by vertically stimulating the spine through the application of a mechanical bed capable of thermal and massage stimulation. For this purpose, after confirming the segmental motion of the spine due to the use of a medical combination stimulation bed for Parkinson's disease patients, VAS, ODI, gait ability, and spiral drawing tests were performed, and the relationship between the variables was identified. In the 10-day visual analog scale and evaluation of low back pain dysfunction, the average trend of decreasing after bed use was confirmed. For walking ability, a decrease in the moving time and an increase in the moving distance were observed. In the spiral drawing test, the mean test time after using bed was significantly lower than before. As a result, it suggested the possibility of using it as an auxiliary method for recovery and pain relief of Parkinson's disease patients due to spinal segmental movement with mechanical heating and massage. However, this study is a preliminary study, and there is a small number of subjects, so additional research is needed that considers the number and condition of future subjects in detail.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2159-2164
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• 2016

Background: A diagnosis of chronic myeloid leukemia (CML) is made on discovery of the presence of a Philadelphia (Ph) chromosome. The success of the treatment of this form of leukemia with tyrosine kinase inhibitor (TKI) is monitored by reduction of the Ph chromosome. Objective: To compare the role of conventional cytogenetic (CC) methods with a real time quantitative polymerase chain reaction (RQ-PCR) and fluorescence in situ hybridization (FISH) for diagnosis and treatment monitoring of CML patients. The secondary outcome was to analyze the treatment responses to TKI in CML patients. Materials and Methods: This was a retrospective study of CML patients who attended the Hematology clinic at Chiang Mai University Hospital from 2005-2010. Medical records were reviewed for demographic data, risk score, treatment response and the results of CC methods, FISH and RQ-PCR. Results: One hundred and twenty three cases were included in the study, 57.7% of whom were male with a mean age of 46.9 years. Most of the patients registered as intermediate to high risk on the Sokal score. At diagnosis, 121 patients were tested using the CC method and 118 (95.9%) were identified as positive. Five patients failed to be diagnosed by CC methods but were positive for BCR-ABL1 using the FISH method. Imatinib was the first-line treatment used in 120 patients (97.6%). In most patients (108 out of 122, 88.5%), a complete cytogenetic response (CCyR) was achieved after TKI therapy and in 86 patients (70.5%) CCyR was achieved long term by the CC method. Five out of the 35 analyzed patients in which CCyR was achieved by the CC method had a positive FISH result. Out of the 76 patients in which CCyR was achieved, RQ-PCR classified patients to only CCyR in 17 patients (22.4%) with a deeper major molecular response (MMR) in 4 patients (5.3%) and complete molecular response (CMR) in 55 patients (72.4%). In the case of initial therapy, CCyR was achieved in 95 patients (79.1%) who received imatinib and in both patients who received dasatinib (100%). For the second line treatment, nilotinib were used in 30 patients and in 19 of them (63.3%) CCyR was achieved. In half of the 6 patients (50%) who received dasatinib as second line or third line treatment CCyR was also achieved. Conclusions: CML patients had a good response to TKI treatment. FISH could be useful for diagnosis in cases where CC analysis failed to detect the Ph chromosome. RQ-PCR was helpful in detecting any residual disease and determining the depth of the treatment response at levels greater than the CC methods.

• Journal of Gastric Cancer
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• v.4 no.3
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• pp.156-163
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• 2004

Purpose: While E-cadherin in normal cells induces calciumdependent cell-cell adhesion, in malignant cell, it plays a role in invasion and metastasis with a reduction of adhesion. Serum soluble E-cadherin is a result of the reduction of the cellular E-cadherin molecule and is found in the circulation of normal individuals, but it is particularly known to be increased in patients with malignancies. Accordingly, through checking the level of serum soluble E-cadherin in patients with gastric cancer and analyzing it in the view of clinicopathology, we investigated whether serum soluble E-cadherin could be translated into a clinicopathologic esult and used as a tumor marker. Materials and Methods: The investigation targeted 88 patients who had been diagnosed as having gastric cancer by the Department of Surgery, St. Mary's Hospital, from October 1, 2002, to July 30, 2003, and who had under gone performed surgery. We measured the level of preoperative serum E-cadherin in the 88 patients by unsing ELISA. Among them, we collected gastric cancer tissues from 54 patients and executed immunohistochemistry for E-cadherin. The samples were compared with normal tissues in terms of both serum E-cadherin level and immunohistochemistry level, as well as with other clinicopathologic factors. Result: The mean serum E-cadherin level of the 88 patients was 4368.7 ng/ml and was significantly higher than the level in 12 normal control patients, 3335.5 ng/ml (P=0.016). In terms of clinicopathology, the serum level of E-cadherin was significantly correlated with increasing age (P=0.0006) and was higher in positive venous invasion patients (P=0.0005). When the E-cadherin immunohistochemical stain was compared with the serum E-cadherin level in 54 patients, no significant statistically meaningful result was obtained (P=0.2881). However, 4 patients with serum E-cadherin levels about 6000 ng/ml were classified into the lower expression group ($<80\%$ of E-cadherin immunohistochemicals stain. In the analysis for 36 patients who were early gastric cancer patients, the serum E-cadherin level in lymph-node-metastatic patients was higher than it was in the other patients (P=0.0442). Conclusion: The serum E-cadherin level in gastric cancer patients was higher than the level in normal control patients. In advanced gastric cancer patients, that the difference was increased. Also, since the E-cadherin level correlated with the serum E-cadherin level with venous invasion, it can be used as an effective tumor marker for gastric cancer. Particularly, in that the serum E-cadherin level correlated with lymph node metastasis in early gastic cancer, it can be used when a therapeutic method for early gastric cancer is selected.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.531-548
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• 2015

Atmospheric Motion Vector (AMV) from satellite images have shown Slow Speed Bias (SSB) in comparison with rawinsonde. The causes of SSB are originated from tracking, selection, and height assignment error, which is known to be the leading error. However, recent works have shown that height assignment error cannot be fully explained the cause of SSB. This paper attempts a new approach to examine the possibility of SSB reduction of COMS AMV by using a new target tracking algorithm. Tracking error can be caused by averaging of various wind patterns within a target and changing of cloud shape in searching process over time. To overcome this problem, Gaussian Mixture Model (GMM) has been adopted to extract the coldest cluster as target since the shape of such target is less subject to transformation. Then, an image filtering scheme is applied to weigh more on the selected coldest pixels than the other, which makes it easy to track the target. When AMV derived from our algorithm with sum of squared distance method and current COMS are compared with rawindsonde, our products show noticeable improvement over COMS products in mean wind speed by an increase of $2.7ms^{-1}$ and SSB reduction by 29%. However, the statistics regarding the bias show negative impact for mid/low level with our algorithm, and the number of vectors are reduced by 40% relative to COMS. Therefore, further study is required to improve accuracy for mid/low level winds and increase the number of AMV vectors.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.1
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• pp.39-47
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• 2006

Purpose: We proposed a new classification of pediatric intussusception based on clinical and radiologic findings. Methods: Data from 88 consecutive patients with intussusception were reviewed. We retrospectively analyzed six factors; patient age, sites of intussusception, symptoms, therapeutic methods, existence of enlarged mesenteric lymph nodes, and ultrasonographic (US) findings from clinical records. Results: 1) There was one neonatal case (1.1%), the others (98.9%) were infants and children. 2) These 87 infant and child cases consisted of 14 cases (16.1%) of small bowel intussusception (SBI) and 73 cases (83.9%) of ileo-colic intussusception (ICI). Of the 14 SBI cases, 12 cases were symptomatic and 2 cases were asymptomatic. The symptomatic group comprised 8 transient cases (66.7%), 3 operative cases (25.0%), and 1 enema-reduction case (8.3%). Two asymptomatic cases were incidentally captured by computed tomography. Of the 73 ICI cases, 19 cases (26.0%) required operation, and 54 (74.0%) enema-reduction. 3) When transient SBI cases were compared with operated SBI cases, enema-reduced and operated ICI cases, the age ($38.0{\pm}22.9$ months) of transient SBI cases were significantly higher than those of the others (p=0.003). Mean mass size ($20.8{\pm}2.7mm$) in transient SBI was significantly smaller than in the others (p=0.0001). 4) No correlation was found between the existence of enlarged mesenteric lymph nodes and therapeutic method or concomitant illness. 5) Most of the target types observed by US were in transient SBI cases, the remainder were in the enema-reduced ICI cases. In terms of the doughnuts type, all 8 cases (34.8%) with an external hypoechoic rim thickness of >8.9mm were treated surgically. Conclusion: Pediatric intussusception may be classified based on clinical and radiologic findings, which are likely to indicate appropriate therapies.

• Journal of Intelligence and Information Systems
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• v.26 no.1
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• pp.135-149
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• 2020

Artificial intelligences are changing world. Financial market is also not an exception. Robo-Advisor is actively being developed, making up the weakness of traditional asset allocation methods and replacing the parts that are difficult for the traditional methods. It makes automated investment decisions with artificial intelligence algorithms and is used with various asset allocation models such as mean-variance model, Black-Litterman model and risk parity model. Risk parity model is a typical risk-based asset allocation model which is focused on the volatility of assets. It avoids investment risk structurally. So it has stability in the management of large size fund and it has been widely used in financial field. XGBoost model is a parallel tree-boosting method. It is an optimized gradient boosting model designed to be highly efficient and flexible. It not only makes billions of examples in limited memory environments but is also very fast to learn compared to traditional boosting methods. It is frequently used in various fields of data analysis and has a lot of advantages. So in this study, we propose a new asset allocation model that combines risk parity model and XGBoost machine learning model. This model uses XGBoost to predict the risk of assets and applies the predictive risk to the process of covariance estimation. There are estimated errors between the estimation period and the actual investment period because the optimized asset allocation model estimates the proportion of investments based on historical data. these estimated errors adversely affect the optimized portfolio performance. This study aims to improve the stability and portfolio performance of the model by predicting the volatility of the next investment period and reducing estimated errors of optimized asset allocation model. As a result, it narrows the gap between theory and practice and proposes a more advanced asset allocation model. In this study, we used the Korean stock market price data for a total of 17 years from 2003 to 2019 for the empirical test of the suggested model. The data sets are specifically composed of energy, finance, IT, industrial, material, telecommunication, utility, consumer, health care and staple sectors. We accumulated the value of prediction using moving-window method by 1,000 in-sample and 20 out-of-sample, so we produced a total of 154 rebalancing back-testing results. We analyzed portfolio performance in terms of cumulative rate of return and got a lot of sample data because of long period results. Comparing with traditional risk parity model, this experiment recorded improvements in both cumulative yield and reduction of estimated errors. The total cumulative return is 45.748%, about 5% higher than that of risk parity model and also the estimated errors are reduced in 9 out of 10 industry sectors. The reduction of estimated errors increases stability of the model and makes it easy to apply in practical investment. The results of the experiment showed improvement of portfolio performance by reducing the estimated errors of the optimized asset allocation model. Many financial models and asset allocation models are limited in practical investment because of the most fundamental question of whether the past characteristics of assets will continue into the future in the changing financial market. However, this study not only takes advantage of traditional asset allocation models, but also supplements the limitations of traditional methods and increases stability by predicting the risks of assets with the latest algorithm. There are various studies on parametric estimation methods to reduce the estimated errors in the portfolio optimization. We also suggested a new method to reduce estimated errors in optimized asset allocation model using machine learning. So this study is meaningful in that it proposes an advanced artificial intelligence asset allocation model for the fast-developing financial markets.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.206-215
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• 2007

Background : The prone position is often used for operations involving the spine and provides excellent surgical access. The complications associated with the prone position include ocular and auricular injuries, and musculoskeletal injuries. In particular, the prone position during general anesthesia causes hemodynamic changes. To evaluate the cardiovascular effects of the prone position in surgical patients during general anesthesia, we investigated the effects on hemodynamic change of the prone position with the Jackson spinal surgery table. Materials and Methods : Thirty patients undergoing spine surgery in the prone position were randomly selected. After induction of general anesthesia, intra-arterial and central venous pressures (CVP) were monitored and cardiac output was measured by $NICO^{(R)}$. We measured stroke volume, cardiac index, cardiac output, mean arterial pressure, heart rate, CVP and systemic vascular resistance (SVR) before changing the position. The same measurements were performed after changing to the prone position with the patient on the Jackson spinal surgery table. Results : In the prone position, there was a significant reduction in stroke volume, cardiac index and cardiac output. The heart rate, mean arterial pressure and CVP were also decreased in the prone position but not significantly. However, the SVR was increased significantly. Conclusion : The degree of a reduced cardiac index was less on the Jackson spinal surgery table than other conditions of the prone position. The reduced epidural pressure caused by free abdominal movement may decrease intraoperative blood loss. Therefore, the Jackson spinal surgery table provides a convenient and stable method for maintaining patients in the prone position during spinal surgery.