• School Mathematics
• /
• v.16 no.4
• /
• pp.691-708
• /
• 2014

In general, the intuitive knowledge that can use in mathematics problem solving is one of the important knowledge to teachers as well as students. So, this study is aimed to analyze the elementary preservice teachers' intuitive knowledge in relation to intuitive and counter-intuitive problem solving. For this, I performed survey to use questionnaire consisting of problems that can solve in intuitive methods and cause the errors by counter-intuitive methods. 161 preservice teachers participated in this study. I got the conclusion as follows. preservice teachers' intuitive problem solving ability is very low. I special, many preservice teachers preferred algorithmic problem solving to intuitive problem solving. So, it's needed to try to improve preservice teachers' problem solving ability via ensuring both the quality and quantity of problem solving education during preservice training courses. Many preservice teachers showed errors with incomplete knowledges or intuitive judges in counter-intuitive problem solving process. For improving preservice teachers' intuitive problem solving ability, we have to develop the teacher education curriculum and materials for preservice teachers to go through intuitive mathematical problem solving. Add to this, we will strive to improve preservice teachers' interest about mathematics itself and value of mathematics.

• Journal of the Korean Society of Radiology
• /
• v.10 no.3
• /
• pp.171-180
• /
• 2016

This study was to evaluate the change in characteristics of concentration of ozone after exposure to high energy radiation in linac room. Background ozone concentration of linac room was measured and compared to ozone concentration around linac room. Background ozone concentration of linac room was mean $17.4{\pm}7.9ppb$. It was 50% of the ozone concentration($36.8{\pm}22.3ppb$) around linac room(p<0.05). The concentration of ozone after exposure to high energy radiation in linac room was elevated to double of background ozone level, intensity after exposure. with exposure time concentration of ozone increased proportionally. It showed maximum level at 130~180seconds and slowed a tendency to saturate. It required more than 10 minutes for ozone concentration in linac room to drop to ozone concentration around linac room. The concentration of ozone after exposure to high energy radiation is high enough to cause specific physical symptoms, such as acute dyspnea or chest pain due to dry cough. Exposure to high concentration of ozone in sealed linac room can aggravate pulmonary disease, so special attention is needed.

• Journal of Science and Technology Studies
• /
• v.4 no.2 s.8
• /
• pp.1-32
• /
• 2004

Korean scientific community has recently argued that, in order to attract talented young people to the science and engineering fields, more ranking positions in the governmental office should be filled in by science and engineering majors. In this context, a special attention has been paid to the Chinese case where science and engineering majors have taken the highest places in Chinese political hierarchy. This paper examines historical and social background of the salience of science and engineering fields in modem China. A closer examination shows that the salience of science and engineering fields was resulted by the distinct historical experiences of China-the socialist reform of higher education system and Cultural Revolution. The former shaped the social conviction that humanities and social sciences are less useful than science and engineering fields. The latter even spread the idea that majoring in humanities or social sciences run the risk of political oppressions. Thus, the salience of science and engineering in China is a social phenomenon reflecting an academic hierarchy forced by the radical politics of modem China. Also, the higher proportion of science and engineering majors in the raking governmental officers has been resulted by a unique Chinese political system, in particular the personnel management system of the Chinese Communist Party that emphasizes practical experiences after college graduation. The comparison of the social position of science and engineering majors in China and Korea without taking account of such historical and social background may therefore mislead our understanding of the cause of and counterplan to the decreasing popularity of science and engineering fields in Korean universities.

• Cross-Cultural Studies
• /
• v.50
• /
• pp.225-259
• /
• 2018

In this study, according to the Institut d'Estudis Catalan, it is noted that the traditional Catalan time telling system is essentially based on delineating time by the use of the 'quarts (=quarters)' of an hour. In this fasion, to tell the time 8:15, 8:30 and 8:45 they use '${\acute{E}}s$ un quart de nou.,' '$S{\acute{o}}n$ dos quarts de nou.,' and '$S{\acute{o}}n$ tres quarts de nou.,' but do not use constructions such as '$S{\acute{o}}n$ les vuit i quinze.,' '$S{\acute{o}}n$ les vuit i trenta/mitja.,' '$S{\acute{o}}n$ les vuit i quaranta-cinc.,' because these expressions are considered to be as dialectal variants or international notation-based variants. Moreover, the traditional Catalan time telling system does not use cardinal numbers, except in the case of 'cinc (five)' and 'deu (ten).' These linguistic phenomenon cause the invention of a unique Catalan digital watch, and has noted special designs for the creation of a Catalan analogue watch. For this reason, the quarter system in colloquial Catalan provokes an enormous interpretative ambiguity in daily routine expressions with 'quarts' like '$S{\acute{o}}n$ quarts of nou.' or 'entre dos i tres quarts' whose meaning is not delineated between sixteen and forty-four minutes. We will argue that the traditional Catalan time telling expressions do not have the use of the subtractive system, and the fraction word 'quart' lacks a specific meaning of fifteen minutes because the Catalan word 'quart' is etymologically related to the classical public bell system, not definitively to the traditional clock system.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.1
• /
• pp.426-433
• /
• 2019

After an earthquake, fire and gas explosions are more likely to cause more casualties in cities with many apartment buildings and large complex buildings. In order to prevent this, seismic design is necessary for the fire protection sprinkler system. However, most systems currently use stainless-steel pipes, although synthetic resin pipes are used in some special places. These materials are susceptible to vibration and earthquakes. This study evaluated the displacement absorption flexibility of polyethylene (PE) and aluminum (Al) multi-layered composite pipes to increase the seismic performance in a vibration environment and during earthquakes. The seismic performance was compared with that of a stainless-steel and PE pipes. The seismic characteristics can be measured by measuring the amount and extent of vibration transmitted by the sprinkler pipe. This method can be used to judge the seismic characteristics to attenuate the vibration during an earthquake. The seismic characteristics of the pipe were verified by comparing the logarithmic attenuation rate to the initial response displacement of the vibration generated by the transverse vibration measurement method.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.47 no.2
• /
• pp.133-145
• /
• 2019

This study was raised by the need to explain why the problems related to private parks have been sustained. In order to identify the fundamental cause, it is necessary to analyze the historical and institutional context of private parks. Therefore, the purpose of this study is to identify the direction of change in the private park system and to derive the characteristics of the system as it currently appears. The framework based on the historical institutionalism was divided into the Park Act (1967-1980), the former of Urban Park Act (1980-1993) and the late of Urban Park Act (1993-2005), and each was assessed using the analysis elements of the institutional environment and the outcomes of implementation. The analysis elements interpreted the path dependency, in which the inertia toward the choice of institution is maintained, despite the change in the environment. The institution took a special form of 'negative systeme' and secured profitability by expanding the types of park facilities while mitigating the criteria. Additionally, the designation of private park promoters as a landowner acted as a means of compensating those with property rights to unexecuted urban parks. The expectation effectiveness on urban park creation was insufficient and the environmental regulatory functions were weakened. Thus, historically, the private park system in Korea has experienced an 'institutional decoupling' as the purpose of the system and the results of actual outcomes are not consistent.

• The Journal of Korea Assosiation for Disability and Oral Health
• /
• v.15 no.1
• /
• pp.60-64
• /
• 2019

Swyer-James syndrome (SJS), also known as Swyer-James-MacLeod syndrome and unilateral hyperlucent lung syndrome, is rare acquired pulmonary disorder develops secondary to infectious etiologies in early childhood. Viral respiratory infection such as adenoviruses or Mycoplasma pneumoniae in infancy or early childhood rarely cause Swyer-James syndrome. It is generally characterized on radiographs by a unilateral small lung with hyperlucency and air trapping on expiration. In many cases unaffected lung tissue functions normally, compensating for affected lung portion. Preoperative assessment is needed to determinate individual's pulmonary function. A 4-year-old boy with Swyer-James syndrome visited Seoul National University Dental Hospital Department of pediatric dentistry for caries treatment. Clinical and radiographic examinations revealed multiple carious lesions on deciduous teeth. Considering patient's underling disease, age, and level of cooperation, dental treatment under general anesthesia was scheduled. Dental treatment was done with composite resin and stainless-steel crown. Since ventilation of Swyer-James syndrome patients was diminished because of airway obstruction, close monitoring of ventilation is necessary during dental treatment. Considering pulmonary pathology, general anesthesia rather than sedation is recommended when special behavior management is required for dental treatment. Swyer-James syndrome patients can tolerate general anesthesia and surgery well, according to several reports.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.5
• /
• pp.417-426
• /
• 2019

This study examined to offer practical implications for the bullying for the prevention and response in early childhood education at the scene of the bullying that occur by to confirm the perception of the bullying to pre-service early childhood teachers. The survey questionnaire was completed by 313 pre-service early childhood teachers. SPSS Win program was used to perform frequency analysis, ANOVA. (1)The perception of bullying were significantly different according to grade and experience of child care practice, classroom observation, education program for taking preventive measure. (2)Teachers' perception about the action that can be seen as bullying followed by 'apply the violence, such as kicking, or were frequent', 'shared in things that often prevents','often to another carrier or shame in front of a friend'. (3)Perception about characteristics of bullying Perpetrators was 'aggressive behavior and talk much' and perception about characteristics of bullying victims was 'shy and not much'. (4)The reason of bullying perpetrators was 'Just for fun without a special reason' and the cause of bullying victims was 'problem of parents' child-rearing attitudes and home environment'. (5)Important institutions to combat bullying prevention followed by teacher, parents and family, community and the nation, preschool educational institution. Teachers guidance content of combat and prevent bullying was 'to be isolated from the class to infants continue to monitor'. Parents guidance content of combat and prevent bullying was 'communicate a lot and attention to children'. Early childhood education institutions guidance content of combat and prevent bullying was 'operations to come up with the bullying prevention education in educational time'. This study indicated that it is necessary to make efforts for increasing perception of bullying in pre-service early childhood teachers.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.1
• /
• pp.19-28
• /
• 2021

Corrosion is the degradation of metals by reaction with the environment. It is difficult to completely remove. Corrosion proceeds rapidly after the protective barrier is destroyed, and several reactions occur that alter the composition and properties of the metal surface and local environments, such as diffusion of metal cations into the matrix, the formation of oxides, and local pH changes. The study of corrosion of steel and iron is of theoretical and practical interest and is receiving considerable attention. Acid solutions, which are widely used in industrial pickling, acid descaling, cleaning and acidification of oil wells, require the use of corrosion inhibitors to suppress corrosion attacks on metallic materials. Physical removal of rust requires expensive special equipment, and chemical removal of it can cause corrosion or shorten the life of the metal. In this study, an eco-friendly rust cleaner was developed using cosmetics and food materials by applying the concept of perm reducing agent and chelate, and applied to remove rust from industrial and hot water pipes and various industrial devices. As a result, it was found that rust cleaners remove rust more effectively and safely compared to conventional treatment methods. At the same time, the rust removal efficiency was 1.75 to 2.5 times better for industrial piping and 1.56 to 2.2 times better for boiler hot water than conventional methods.

• Journal of Practical Engineering Education
• /
• v.14 no.1
• /
• pp.165-177
• /
• 2022

The purpose of this study is to present the direction of employment guidance for long-term service through the analysis of the cause of employment of employed students who graduated from specialized high school. In particular, the purpose is to present student guidance plans for long-term service by analyzing personal reasons for students graduating from commercial high schools and policy factors for individual, school, company, and government service after employment. To this end, a survey was conducted for graduates of commercial high schools nationwide, and the validity, reliability, and causality of the survey data were analyzed by applying Exploratory Factor Analysis, Cronbach's Alpha, and decision tree analysis techniques. We found that personal goal setting for employment is an important factor for working for more than 1 year, personal relationships at work and personal characteristics are important factors for working for more than 3 years. In addition, we found that the reason for getting a job is that personal reasons and school recommendations are great, special lectures on employment, camps, and 'advice from seniors and teachers' programs are helpful in finding a job, and accounting and computer related subjects are helpful for long-term employment. Accordingly, in specialized high schools, it is required to prepare specific instructional measures for education such as setting personal goals and the formation of human relationships that are the basis of social life, and to actively operate the above subjects and programs to help with employment and longevity.