• Investigative Magnetic Resonance Imaging
• /
• v.15 no.1
• /
• pp.41-47
• /
• 2011

Purpose : To evaluate the cause of internal jugular vein (IJV) obstruction on contrast enhanced 3D MR angiography (CE-MRA) using contrast enhanced computed tomography (CE-CT). Materials and Methods : A total number of 30 patients were enrolled, who underwent both head and neck CE-MRA and CE-CT from 2005 to 2008. We defined obstruction group which had IJV obstruction and control group which had no IJV obstruction on CE-MRA. The following parameters were measured from axial images of CE-CT: 1) diameter of IJV; 2) distance between the styloid process and ipsilateral lateral mass of the atlas; 3) maximum area of lateral mass of the atlas. Each parameter was compared between obstruction group and control group. Results : The diameter of IJV and distance between the styloid process and lateral mass of the atlas at IJV obstruction side in obstruction group were $1.6{\pm}1.0\;mm$ and $4.1{\pm}2.1\;mm$ respectively, which resulted in statistical significance (p<0.01). The maximum area of lateral mass of the atlas at IJV obstruction side in obstruction group was $103.4{\pm}25.3\;mm^2$ which is significantly larger than in control group (p<0.05). Conclusion : We found that the cause of IJV obstruction on CE-MRA could be narrow space between the styloid process and the lateral mass of the atlas, which was related with asymmetric larger area of lateral mass of atlas.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.1
• /
• pp.15-24
• /
• 2012

In this paper, we suggest the dynamic-response-free SMPS using a new high-resolution DPWM generator based on switched-capacitor delay technique. In the proposed system, duty ratio of DPWM is controlled by voltage slope of an internal capacitor using switched-capacitor delay technique. In the proposed circuit, it is possible to track output voltage by controlling current of the internal capacitor of the DPWM generator through comparison between the feedback voltage and the reference voltage. Therefore the proposed circuit is not restricted by the dynamic-response characteristic which is a problem in the existing SMPS using the closed-loop control method. In addition, it has great advantage that ringing phenomenon due to overshoot/undershoot does not appear on output voltage. The proposed circuit can operate at switching frequencies of 1MHz~10MHz using internal operating frequency of 100 MHz. The maximum current of the core circuit is 2.7 mA and the total current of the entire circuit including output buffer is 15 mA at the switching frequency of 10 MHz. The proposed circuit has DPWM duty ratio resolution of 0.125 %. It can accommodate load current up to 1 A. The maximum ripple of output voltage is 8 mV. To verify operation of the proposed circuit, we carried out simulation with Dongbu Hitek BCD $0.35{\mu}m$ technology parameter.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.15 no.3
• /
• pp.103-119
• /
• 2020

This study aimed to derive theoretical and practical implications by analyzing the relationship between adversity quotient, entrepreneurial orientation, and customer orientation, which are the internal competency of start-up entrepreneurs affecting the performance of a small business CEO. As in previous domestic studies, we deviated from analyzing internal competency as a single-dimensional functional relationship to business performance, and attempted to explain the relationship between the internal competences of start-up entrepreneurs. Empirical analysis was conducted by setting the adversity quotient as an independent variable, the entrepreneurial orientation as a parameter, and the customer orientation as a dependent variable. As a result of the analysis, first, it was found that control and ownership, which are sub-elements of adversity quotient, have a positive effect on entrepreneurial orientation and customer orientation. Second, entrepreneurial orientation was found to have a positive effect on customer orientation. Third, it was found that only the ownership of the adversity quotient had a positive effect on customer orientation through the mediating effect of entrepreneurial orientation. In other words, it was found that the entrepreneur's ownership influences customer orientation through entrepreneurial orientation. On the other hand, endurance, sub-element of adversity quotient, was found to have no significant effect on entrepreneurial orientation and customer orientation. This means that in the rapidly changing New Normal era, endurance of entrepreneur can no longer have a large impact on entrepreneurial orientation and customer orientation. This study gives implications for the entrepreneur's competencies that must be developed first and the tendency to be developed together. Furthermore, it can be helpful in policy designing start-up support programs and guidelines for investors' investment standards.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.6
• /
• pp.527-534
• /
• 2016

The non-rail mobile rack, which is used for cargo storage, can improve the storage capacities of logistics centers. Furthermore, it has the advantage that it can be used in traditional logistics centers without making any changes or renovation, such as installing rails. However, when the rack is operated by separated drive actuators mounted on the left and the right wheels, precise position control of the wheels is necessary even if the unbalanced cargo weight on the rack would affect the control. Therefore, internal synchronization control for position tracking between the left and right wheels on the non-rail mobile rack is necessary in this study. In addition, external synchronization control for realizing the same straight movements between mobile racks is necessary. For the internal and the external synchronization control, we propose a synchronization control algorithm based on the repetitive control theory. An internal synchronization control algorithm with repetitive control theory requires the application of the robust servo control method owing to parameter variations. In this case, we can set up the gains for the robust servo control system by considering the cargo variations on the mobile rack. Furthermore, for developing the external synchronization control algorithm, we use a double repetitive control system to perform synchronization control between mobile racks. The efficiency of the proposed control algorithm will be verified by simulation and experimental results. The proposed algorithm can be easily applied in the industry.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.04a
• /
• pp.835-841
• /
• 2013

Modern solid-state gyroscopes (HRG) with hemispherical resonators from high-purity quartz glass and special surface superfinishing and ultrathin gold coating become the best instruments for precise-grade inertial reference units (IRU) targeting long-term space missions. Designing of these sensors could be a notable contribution into development of Korea as a space nation. In participial, 40mm diameter thin-shell resonator from high-purity fused quartz, fabricated as a single-piece with its supporting stem has been designed, machined, etched, tuned, tested, and delivered by STM Co. (ATS of Ukraine) several years ago; an extremely-high Q-factor (upto 10~20 millions) has been shown. Understanding of the best way how to match such a unique sensor with inner glass assembly of the gyro means how to use the high potential in a maximal extent; and this has become the urgent task. Inner quartz glass assembly has a very thin indium (In) layer soldered the resonator and its silica base (case), but effects of internal resonances between operational modal pair of the shell-cup and its side (parasitic) modes can notable degrade the potential of the sensor as a whole, instead of so low level of resonator's intrinsic losses. Unfortunately, there are special combinations of dimensions of the parts (so-called, "resonant sizes"), when intensive losses of energy occurs. The authors proposed to use the length of stem's fixture as an additional design parameter to avoid such cases. So-called, a cyclic scheme of finite element method (FEM) and ANSYS software were employed to estimate different combinations of gyro assembly parameters. This variant has no mismatches of numerical origin due to FEM's discrete mesh. The optimum length and dangerous "resonant lengths" have been found. The special attention has been paid to analyses of 3D effects in a cup-stem transient zone, including determination of a difference between the positions of geometrical Pole of the resonant hemisphere and of its "dynamical Pole", i.e., its real zone of oscillation node. Boundary effects between the shell (cup) and 3D short "beams" (inner and outer stems) have been ranged. The results of the numerical experiments have been compared with the classic model of a quasi-hemispherical shell band with inextensional midsurface, and the solution using Rayleigh's functions of the $1^{st}$ and $2^{nd}$ kinds. To guarantee the truth of the recommended sizes to a designer of the real device, the analytical and FEM results have been compared with experimental data for a party of real resonators. The consistency of the results obtained by different means has been shown with errors less than 5%. The results notably differ from the data published earlier by different researchers.

• Journal of Radiation Protection and Research
• /
• v.34 no.2
• /
• pp.87-94
• /
• 2009

Tritium is the one of the dominant contributors to the internal radiation exposure of workers at pressurized heavy water reactors (PHWRs). This nuclide is likely to release to work places as tritiated water vapor (HTO) from a nuclear reactor and gets relatively easily into the body of workers by inhalation. Inhaled tritium usually reaches the equilibrium of concentration after approximately 2 hours inside the body and then is excreted from the body with a half-life of 10 days. Because tritium inside the body transports with body fluids, a whole body receives radiation exposure. Internal radiation exposure at PHWRs accounts for approximately 20-40% of total radiation exposure; most internal radiation exposure is attributed to tritium. Thus, tritium is an important nuclide to be necessarily monitored for the radiation management safety. In this paper, metabolism for tritium is established using its excretion rate results in urine samples of workers at PHWRs and an effective half-life, a key parameter to estimate the radiation exposure, was derived from these results. As a result, it was found that the effective half-life for workers at Korean nuclear power plants is shorter than that of International Commission on Radiological Protection guides, a half-life of 10 days.

• The Journal of Dong Guk Oriental Medicine
• /
• v.8 no.1
• /
• pp.107-116
• /
• 1999

The effects of Sosokmyung-tang(小續命湯) on global cerebral ischemia and cerebral in farction by MCA(middle cerebral artery) occlusion were evaluated in this study. This study was performed to investigate that Sosokmyung-tang would be useful for cerebrovascular diseases. In the case of global cerebral ischemia, ICR mice were used and divided into three group at random. Control group was treated after oral administration of normal saline, experimental group was treated after oral administration of 10.4mg/20g/day of Sosokmyung-tang extract. The multiple parameter of global cerebral ischemia included the duration of coma of KCN(potassium cyanide)-injected(1.2mg/kg, i.v) group and the survival time of KCN-injected(3.0mg/kg, i.v) group. In the case of cerebral infarction by MCA occlusion, Sprague-Dawley rats were used and divided into three group at random. Control group was given nothing before MCA occlusion, experimental group was given 157.2mg/250g/day of Sosokrnyung-tang extract before MCA occlusion. We investigated edema and ischemic ratio in 8 slices of rats' brain after MCA occlusion. The results were obtained as follows : 1. Sosokrnyung-tang significantly shortened the duration of coma of KCN-injected(1.2mg/kg,i.v) group and lengthened the survival time of KCN-injected(3.0mg/kg, i.v) group. 2. Sosokmyung-tang significantly decreased cerebral edema and ischemic ratio in rats after MCA occlusion. From the above results, it was concluded that Sosokmyung-tang can be effectively applied to cerebrovascular diseases.

• Korean Journal of Radiology
• /
• v.23 no.11
• /
• pp.1078-1088
• /
• 2022

Objective: To develop and validate a model using radiomics features from apparent diffusion coefficient (ADC) map to diagnose local tumor recurrence in head and neck squamous cell carcinoma (HNSCC). Materials and Methods: This retrospective study included 285 patients (mean age ± standard deviation, 62 ± 12 years; 220 male, 77.2%), including 215 for training (n = 161) and internal validation (n = 54) and 70 others for external validation, with newly developed contrast-enhancing lesions at the primary cancer site on the surveillance MRI following definitive treatment of HNSCC between January 2014 and October 2019. Of the 215 and 70 patients, 127 and 34, respectively, had local tumor recurrence. Radiomics models using radiomics scores were created separately for T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE-T1WI), and ADC maps using non-zero coefficients from the least absolute shrinkage and selection operator in the training set. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of each radiomics score and known clinical parameter (age, sex, and clinical stage) in the internal and external validation sets. Results: Five radiomics features from T2WI, six from CE-T1WI, and nine from ADC maps were selected and used to develop the respective radiomics models. The area under ROC curve (AUROC) of ADC radiomics score was 0.76 (95% confidence interval [CI], 0.62-0.89) and 0.77 (95% CI, 0.65-0.88) in the internal and external validation sets, respectively. These were significantly higher than the AUROC values of T2WI (0.53 [95% CI, 0.40-0.67], p = 0.006), CE-T1WI (0.53 [95% CI, 0.40-0.67], p = 0.012), and clinical parameters (0.53 [95% CI, 0.39-0.67], p = 0.021) in the external validation set. Conclusion: The radiomics model using ADC maps exhibited higher diagnostic performance than those of the radiomics models using T2WI or CE-T1WI and clinical parameters in the diagnosis of local tumor recurrence in HNSCC following definitive treatment.

• Tuberculosis and Respiratory Diseases
• /
• v.44 no.1
• /
• pp.93-103
• /
• 1997

Background : Malnutrition is a common finding in patients with chronic obstructive pulmonary disease, especially in the emphysema group. Although the mechanism of malnutrition is not confirmed, it is believed to be a relative deficiency caused by hypermetabolism due to increased energy requirements of the respiratory muscles, rather than a dietary deficiency. Malnutrition in chronic obstructive pulmonary disease is not a merely coincidental finding. It is known that the nutritional status correlates with physiologic parameters including pulmonary function, muscular power, and exercise performance, and is one of the important and independent prognostic factors of the disease. Methods : Patients with chronic obstructive pulmonary disease Yongdong Severance Hospital from May, 1995 to March, 1996 and age-matched healthy control group were studied. Survey of nutritional intake, anthropometric measurements and biochemical tests were done to assess nutritional status. Relationship between nutritional status and FEV1 (forced expiratory volume at one second), which was a significant functional parameter, was assessed. Results : 1) The patient group was consisted of 25 males with mean age of 66.1years and FEV1 of $42{\pm}14%$ of predicted values. The control group was consisted of 26 healthy males with normal pulmonary function, whose mean age was 65.0 years. 2) The ratio of calorie intake/calorie requirement per day was $107{\pm}28%$ in the patient group, and $94{\pm}14%$ in the control group, showing a tendency of more nutritional intake in patient group(B=0.06). 3) There were significant differences between the patient group and control group in percent ideal body weight(92.8% vs 101.6%, p=0.024), body mass index($20.0kg/m^2$ VS $21.9kg/m^2$, p=0.015), and handgrip strength(29.0kg vs 34.3kg, p=0.003). However, there were no significant differences in triceps skinfold thickness, mid-arm muscle circumference, albumin, and total lymphocyte count between two groups. Percentage of underweight population was 40%(10/25) in the patient group, and 15%(4/26) in the control group. 4) The percent ideal body weight, triceps skinfold thickness, and mid-arm muscle circumference had significant correlation with FEV1. Conclusion : The patients with chronic obstructive pulmonary disease showed significant depletion in nutritional parameters such as body weight and peripheral muscle strength, while absolute amount of dietary intake was not insufficient. Nutritional parameters were well correlated with FEV1.

• Tuberculosis and Respiratory Diseases
• /
• v.61 no.3
• /
• pp.227-232
• /
• 2006

Background: In the measurement of bronchodilator reversibility, the forced expiratory volume in one second($FEV_{1}$) and the forced vital capacity(FVC) are commonly used parameters and recommended criteria for the reversibility requiring an increase of more than 200ml and 12% above the baseline, respectively. However, aged patients do not often meet the criteria of an increase in volume(>200ml) even though the medical history of that patient is adequate for asthma. This study investigated the role of the forced expiratory volume in six seconds($FEV_{6}$) in the bronchodilator reversibility test in elderly patients. Methods: A total of 236 patients more than 65 years of age with a $FEV_{1}$/FVC ratio<80% were enrolled in this study. The bronchodilator revesibility tests were examined. With the setting $FEV_{1}$ as the baseline, the patients were divided into three groups; Group I : $$FEV_{1}{\geq_-}80%$$ of the predicted value, Group II : 60%<$FEV_{1}$<80% of the predicted value, Group III : $$FEV_{1}{\leq_-}60%$$ of the predicted value. Results: Positive reversibility in the $FEV_{1}$, $FEV_{6}$, and FVC was in 33(14.0%), 49(20.8%) and 55(23.3%). However, Group III presented with reversibility in the $FEV_{1}$, $FEV_{6}$, and FVC in 15(22.4%), 30(44.8%) and 32(47.8%) respectively. Conclusions: The $FEV_{6}$ might be used as a complementary parameter in bronchodilatror reversibility in elderly patients. However, more study will be needed to determine the usefulness of $FEV_{6}$ in bronchodilator reversibility test.