• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.1
• /
• pp.86-93
• /
• 2015

Globally, wind power development is experiencing dramatic growth and wind power penetration levels are increasing. Wind generation is highly variable in time and space and it doesn't guarantee the system reliability and secure system operation. As wind power capacity becomes a significant portion of total generation capacity, the reliability assessment for wind power are therefore needed. At present, this operational reliability assessment is focusing on a generation adequacy perspective and does not consider transmission reliability issues. In this paper, we propose the critical transmission operating constraint prediction(CTOCP) system with high wind power penetration to enhance transmission reliability.

• Research in Mathematical Education
• /
• v.25 no.2
• /
• pp.135-158
• /
• 2022

This study aimed to building models to understand the relationships between reasoning resources and content knowledge. We applied Support Vector Machine and linear models to the data including fifth graders' scores in the Cornel Critical Thinking Test and the Iowa Assessments, demographic information, and learning science approach (a student-centered approach to learning called the Science Writing Heuristic [SWH] or traditional). The SWH model showing the relationships between critical thinking domains and academic achievement at grade 5 was developed, and its validity was tested across different learning environments. We also evaluated the stability of the model by applying the SWH models to the data of the grade levels. The findings can help mathematics educators understand how critical thinking and achievement relate to each other. Furthermore, the findings suggested that reasoning in mathematics classrooms can promote performance on standardized tests.

• Tuberculosis and Respiratory Diseases
• /
• v.73 no.4
• /
• pp.231-233
• /
• 2012

Tadalafil is a phosphodiesterase-5 inhibitor (PDE5I), which is widely used to treat erectile dysfunction. Although PDE5Is have excellent safety profiles, and most of the side effects are mild, rare serious adverse events have been reported in association with PDE5Is. Thrombosis is one of those events, and a few previous reports have suggested the association of PDE5Is with thrombosis. We report the case of a 61-year-old male who developed pulmonary embolism combined with pulmonary infarction directly after taking tadalafil. Both the patient and the physician suspected tadalafil as the culprit drug, as the patient was in an otherwise healthy condition. However, after extensive evaluation, we noticed that factor VIII levels were elevated. Prior reports suggesting the association between thrombosis and PDEIs either lack complete information on coagulation factors, or show inconsistencies in their results. Physicians should operate caution prior to accepting the diagnosis of adverse drug reaction.

• Journal of Korean Neurosurgical Society
• /
• v.56 no.4
• /
• pp.330-333
• /
• 2014

Objective : To identify the accuracy and efficiency of the computed tomographic (CT)-based navigation system on upper cervical instrumentation, particularly C1 lateral mass and C2 pedicle screw fixation compared to previous reports. Methods : Between May 2005 and March 2014, 25 patients underwent upper cervical instrumentation via a CT-based navigation system. Seven patients were excluded, while 18 patients were involved. There were 13 males and five females; resulting in four degenerative cervical diseases and 14 trauma cases. A CT-based navigation system and lateral fluoroscopy were used during the screw instrumentation procedure. Among the 58 screws inserted as C1-2 screws fixation, their precise positions were evaluated by postoperative CT scans and classified into three categories : in-pedicle, non-critical breach, and critical breach. Results : Postoperatively, the precise positions of the C1-2 screws fixation were 81.1% (47/58), and 8.6% (5/58) were of non-critical breach, while 10.3% (6/58) were of critical breach. Most (5/6, 83.3%) of the critical breaches and all of non-critical breaches were observed in the C2 pedicle screws and there was only one case of a critical breach among the C1 lateral mass screws. There were three complications (two vertebral artery occlusions and a deep wound infection), but no postoperative instrument-related neurological deteriorations were seen, even in the critical breach cases. Conclusion : Although CT-based navigation systems can result in a more precise procedure, there are still some problems at the upper cervical spine levels, where the anatomy is highly variable. Even though there were no catastrophic complications, more experience are needed for safer procedure.

• Journal of the Korea Safety Management & Science
• /
• v.11 no.3
• /
• pp.19-26
• /
• 2009

It is becoming more and more important to develop safety-critical systems with special attention. Examples of the safety-critical systems include the mass transportation systems such as high speed trains, airplanes, ships and so forth. Safety critical issues can also exist in the development of atomic power plants that are attracting a great deal of attention recently as oil prices are sky-rocketing. Note that the safety-critical systems are in general large-scale and very complex for which case the effects of adopting the systems engineering (SE) approach has been quite phenomenal. Furthermore, safety-critical requirements should necessarily be realized in the design phase and be effectively maintained thereafter. In light of these comments, we have considered our approach to developing safety-critical systems to be based on the method combining the systems engineering and safety management processes. To do so, we have developed a design environment by constructing a whole life cycle model in two steps. In the first step, the integrated process model was developed by integrating the SE (ISO/IEC 15283) and systems safety (e.g., hazard analysis) activities and implemented in a computer-aided SE tool environment. The model was represented by three hierarchical levels: the life-cycle level, the process level, and the activity level. As a result, one can see from the model when and how the required SE and safety processes have to be carried out concurrently and iterately. Finally, the design environment was verified by the computer simulation.

• Child Studies in Asia-Pacific Contexts
• /
• v.3 no.2
• /
• pp.139-158
• /
• 2013

The present study investigated the direct and interactive effects of children's temperament and mothers' reactions to hypothetical vignettes of children's aggression on 3- to 6-year-old children's overt aggression (OA) and relational aggression (RA). A total of 317 mothers of 3- to 6-year-old children and 26 teachers from eight day-care centers and kindergartens were contacted. Each mother reported her child's background, assessed her child's temperament and responded to the Mothers' Reaction to Hypothetical Vignettes of Children's Aggression (MRCA) scale. Children's OA and RA were assessed by teachers. Results showed that high levels of children's surgency predicted children's OA and RA. Although mothers' reactions did not predict children's OA and RA directly, significant interactions indicated that mothers' restrictive reactions were more strongly related to children's OA for children with high levels of surgency and low levels of effortful control. In addition, mothers' responsive reactions were more strongly related to children's OA for children with low levels of surgency. This study demonstrates that relative contributions of children's temperament and mothers' reactions differ according to the form of children's aggression. It also shows that certain types and levels of mothers' reactions to children's aggressive behavior can be critical for children with certain types and levels of temperament in developing children's overt aggression. The findings of this study can be applied to building early prevention and future intervention programs for young children's aggression.

• Culinary science and hospitality research
• /
• v.23 no.6
• /
• pp.20-26
• /
• 2017

To guarantee the safety of rice cake production, the Hazard Analysis Critical Control Points system was applied to the production process. The purpose of this study was to analyze the microbiological hazards of the manufacture of rice cakes, and establish critical limits in the process of the manufacturing rice cakes. To control the microbiological hazards, the sterilization process was set to a critical limit. The process of manufacturing rice cakes can reduce these microbiological hazards during the steaming process. A microorganism test for each specimen was conducted three times and compared with before and after steaming processes. The finished product was conducted by microbiology experiment and the validity of the steaming process was verified. The results were determined to be capable of reducing the biological element of Critical Control Point via the steaming process. Microbiology such as aerobic plate count, coliform, Escherichia coli(E. coli), Listeria monocytogenes, Enterohemorrhagic E. coli, Salmonella spp., Bacillus cereus, Staphylococcus aureus and Clostridium perfringens was evaluated by the experimental method of Korean Food Standards Codex. Aerobic plate count was reduced by steaming process, and no microorganism were detected. All rice cakes in the finished product were judged to be safe for both the Escherichia coli and general bacteria. In conclusion, it suggested that a HACCP plan was necessary for management standard and systematic approach in the establishment of critical limit, problem resolution, verification method, education, and records management. Based on this study, it is intended to provide a baseline for improving quality control standards and improving hygiene levels for small manufacturers.

• Tuberculosis and Respiratory Diseases
• /
• v.67 no.4
• /
• pp.359-363
• /
• 2009

Immunoglobulin G4 (IgG4) related autoimmune diseases are characterized by high serum IgG4 concentrations, sclerosing inflammation of numerous IgG4-positive lymphoplasma cells of varying origin, and a positive response to steroid treatment. Autoimmune pancreatitis, sclerosing cholangitis, and retroperitoneal fibrosis are representative presentations of IgG4 related autoimmune disease. Herein, we describe 2 patients (40-years-old woman and 47-years-old man) diagnosed with pulmonary involvement of IgG4-related autoimmune disease. The patients were admitted for an evaluation of the lung mass or multiple lung nodules found on chest radiography. Surgical lung biopsies were performed and pathologic finding revealed lymphoplasmacytic sclerosing inflammation with numerous IgG4 positive cells. The patients had elevated serum total IgG and IgG4 levels. Treatment consisted of high dose methylpredinisolone (1 mg/kg/day) and demonstrated good responsiveness. However, one patient experienced 2 relapses while being tapered off of steroid treatment.

• Journal of Korean Association for Spatial Structures
• /
• v.20 no.4
• /
• pp.149-158
• /
• 2020

The governing equation for a dome-type shallow spatial truss subjected to a transverse load is expressed in the form of the Duffing equation, and it can be derived by considering geometrical non-linearity. When this model under constant load exceeds the critical level, unstable behavior is appeared. This phenomenon changes sensitively as the number of free-nodes increases or depends on the imperfection of the system. When the load is a periodic function, more complex behavior and low critical levels can be expected. Thus, the dynamic unstable behavior and the change in the critical point of the 3-free-nodes space truss system were analyzed in this work. The 4-th order Runge-Kutta method was used in the system analysis, while the change in the frequency domain was analyzed through FFT. The sinusoidal wave and the beating wave were utilized as the periodic load function. This unstable situation was observed by the case when all nodes had same load vector as well as by the case that the load vector had slight difference. The results showed the critical buckling level of the periodic load was lower than that of the constant load. The value is greatly influenced by the period of the load, while a lower critical point was observed when it was closer to the natural frequency in the case of a linear system. The beating wave, which is attributed to the interference of the two frequencies, exhibits slightly more behavior than the sinusoidal wave. And the changing of critical level could be observed even with slight changes in the load vector.

• Tuberculosis and Respiratory Diseases
• /
• v.74 no.1
• /
• pp.7-14
• /
• 2013

Background: Fractional exhaled nitric oxide (FeNO) can be measured easily, rapidly, and noninvasively for the assessment of airway inflammation, particularly mediated by eosinophil, such as asthma. In bronchiectasis (BE), the pathogenesis has been known as chronic airway inflammation and infection with abnormal airway dilatation; however, there are little studies to evaluate the role of FeNO in BE. Methods: From March 2010 to February 2012, 47 patients with BE, diagnosed by high resolution computed tomography (HRCT), performed FeNO, compared with asthma and chronic obstructive pulmonary disease (COPD). All patients carried out a complete blood count including eosinophil count, chemistry, sputum examination, and spirometry, if indicated. A retrospective analysis was performed to elucidate the clinical role of FeNO in BE patients. Results: The mean FeNO levels in patients with BE was $18.8{\pm}1.5$ part per billion (ppb), compared to $48.0{\pm}6.4$ and $31.0{\pm}4.3$ in those with asthma and COPD, respectively (p<0.001). The FeNO levels tended to increase along with the disease severity scores by HRCT; however, it was statistically not significant. FeNO in BE with a co-infection of nontuberculous mycobacteria was the lowest at $17.0{\pm}3.5$ ppb among the study population. Conclusion: FeNO in BE was lower than other chronic inflammatory airway diseases, particularly compared with asthma. For clinical application of FeNO in BE, more large-scaled, prospective studies should be considered.