• Journal of Wetlands Research
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• v.25 no.2
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• pp.75-82
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• 2023

Data for measuring the flow rate of streams are used as important basic data for the development and maintenance of water resources, and many experts are conducting research to make more accurate measurements. Especially, in Korea, monsoon rains and heavy rains are concentrated in summer due to the nature of the climate, so floods occur frequently. Therefore, it is necessary to measure the flow rate most accurately during a flood to predict and prevent flooding. Thus, the U.S. Geological Survey (USGS) introduces 1, 2, 3 point method using a flow meter as one way to measure the average flow rate. However, it is difficult to calculate the average flow rate with the existing 1, 2, 3 point method alone.This paper proposes a new 1, 2, 3 point method formula, which is more accurate, utilizing one probabilistic entropy concept. This is considered to be a highly empirical study that can supplement the limitations of existing measurement methods. Data and Flume data were used in the number of holesman to demonstrate the utility of the proposed formula. As a result of the analysis, in the case of Flume Data, the existing USGS 1 point method compared to the measured value was 7.6% on average, 8.6% on the 2 point method, and 8.1% on the 3 point method. In the case of Coleman Data, the 1 point method showed an average error rate of 5%, the 2 point method 5.6% and the 3 point method 5.3%. On the other hand, the proposed formula using the concept of entropy reduced the error rate by about 60% compared to the existing method, with the Flume Data averaging 4.7% for the 1 point method, 5.7% for the 2 point method, and 5.2% for the 3 point method. In addition, Coleman Data showed an average error of 2.5% in the 1 point method, 3.1% in the 2 point method, and 2.8% in the 3 point method, reducing the error rate by about 50% compared to the existing method.This study can calculate the average flow rate more accurately than the existing 1, 2, 3 point method, which can be useful in many ways, including future river disaster management, design and administration.

• Journal of Korean Dental Hygiene Science
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• v.6 no.1
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• pp.37-50
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• 2023

Background: This study investigated the structural relationships among justice, test anxiety, and school reliability s non-face-to-face tests of dental hygiene students. Methods: A survey was conducted with 267 dental hygiene students. The survey items included general characteristics, opinions on evaluation, the fairness of non-face-to-face tests (distributive, procedural, and interactional justice), school satisfaction, and school reliability. For statistical analysis, independent-sample t-tests, one-way ANOVA, and structural modeling analyses were performed. Results: Among factors that directly affected distributive justice and reliability towards non-face-to-face tests, the higher the interactional justice (β=0.401, p<0.001) and distributive justice (β=0.232, p=0.002) levels, the higher the school satisfaction. The higher the school satisfaction (β=0.606, p<0.001) and procedural justice (β=0.299, p<0.001) levels, the higher the perceived reliability of the school. Factors that indirectly affected school reliability included interactional justice (β=0.243, p=0.010) and distributive justice (β=0.141, p=0.010). Interactional justice (β=0.592, p=0.010) and distributive justice (β=0.208, p=0.010) were the factors affecting school satisfaction. Moreover, factors that influenced school reliability were distributive justice (β=0.56, p=0.010), interactional justice (β=0.332, p=0.010), procedural justice (β=0.229, p=0.010), and distributive justice (β=0.116, p=0.010). Conclusions: Students will trust and be satisfied with schools when schools and professors sufficiently provide information on face-to-face tests and ensure proper procedures to achieve reasonable grades as rewards for exerted time and effort. Furthermore, this study provides a reference base for developing a variety of content for fair, non-face-to-face tests, thereby allowing students to trust their schools.

• Economic Analysis
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• v.26 no.1
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• pp.1-33
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• 2020

Recent discussions about a minimum wage increase (MWI) and its influence on the economy have mainly focused on the quantitative aspects, such as labor costs and employment. However, concerning the qualitative aspects, an MWI could have positive effects by enhancing firm productivity and crowding out marginal firms from the market. These positive effects of an MWI can offset, to some extent, its potential negative effects - increasing labor costs and decreasing employment, among others. In this regard we empirically examine the impact of an MWI on firm productivity (total factor productivity). Using firm level panel data from the manufacturing industry in Korea, we calculate the influence rates of a minimum wage by sector and by firm size (number of workers), and analyze its effects on firm productivity. In particular, the production functions of the firms are estimated by taking into account endogeneity among the input factors, in order to resolve the drawbacks of existing studies - underestimating the capital factor coefficient and overestimating the labor factor coefficient. This study finds that the influences of an MWI on wages, employment, and productivity are substantially different across sectors and firm sizes. While an MWI has shown to have positive influences on productivity growth in the manufacturing industry as a whole, each sector demonstrates a different direction of effect, and the degree of productivity change also varies by sector. The impacts of an MWI on firm productivity are generally estimated to be more negative for smaller firms, but in some sectors the effects are found to be positive. In addition, the wage increases resulting from an MWI seem to cause a productivity enhancement across all sectors in the manufacturing industry. The policy implications of this study are as follows. Considering the empirical findings that an MWI causes an increase in productivity in many sectors of the manufacturing industry, it would be desirable to take into consideration not only the negative side effects but also the positive effects of an MWI when designing any future minimum wage policy. Moreover, in spite of there being a uniform minimum wage, this study finds that the diverse influence rates of a minimum wage across firms have different impacts on wages, employment, and productivity across sectors or firm size. This finding could be conducive to discussions about differentiation among minimum wage schemes by sector or firm size.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.197-206
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• 2023

Recently, the international community, including the International Maritime Organization (IMO), has strengthened regulations on air pollution emissions of ships, and eco-friendly ships are actively being developed to reduce exhaust gas emissions. Among them, rotor sail (RS), a wind-assisted ship propulsion system, is attracting attention again. RS is a cylindrical device installed on the ship deck, that generates hydrodynamic lift using a magnus effect. This is a next generation eco-friendly auxiliary propulsion technology, and Enercon company, which developed RS-applied ships, announced that fuel savings of more than 30% are possible. In this study, optimal installation conditions such as RS spacing and arrangement type were selected when multiple RSs were installed on ships. AR=5.1, SR=1.0, and D_e/D was fixed at 2.0 according to the RS arrangement, and the wind direction was considered only for the unidirectional +y-axis. Regarding arrangement conditions, five conditions were set at 3D intervals in the +x-axis direction from 3D to 15D and five conditions in the +y-axis direction from 5D to 25D. C_L, C_D and aerodynamic efficiency (C_L/C_D) were compared according to the square(□) and diamond(◇) shape arrangements. Consequently, the effect of RS on the longitudinal distance was not significantly different. However, in the case of RS flow characteristics according to the transverse distance, the interaction effect of RS was the greatest when the two RSs almost matched the wind direction. In the case of the RS flow characteristics according to the arrangement, notably, when the wind blew in the forward (0°) direction, the diamond (◇) arrangement was least affected by the backward flow between RSs.

• Korea Science and Art Forum
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• v.20
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• pp.255-265
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• 2015

When it comes to how to define history·culture streets, people think of the streets as street environments that would create local identity in association with this local community's particular historical and cultural resources as well as urban streets. In order to build such streets, any relevant fields first need to apply some original design based on understanding on historical and cultural resources. With Street of Gaya in Gimhae selected as a research subject, this study aims to look into components and color characteristics of the history·culture street and finds ways to create other streets of that kind. As a frame to understand the history·culture streets, what this study would come up with is considered significant in that it helps the value to be re-recognized and promoted. In order to achieve the research goal, the study (1) extracted components of streetscapes referring to relevant previous researches and then, (2) analyzed a current status of these components of Street of Gaya via field investigation. (3) The study examined color characteristics of each of the components. Findings of the research are summarized as follows. (1) From a comprehensive point of view, the study categorized and subdivided the components of the history·culture street into nonphysical and physical elements. (2) After analyzing the current status of the components, the study learned that Street of Gaya basically consists of historical and cultural remains and sculptures as well as street facilities. (3) Results of the color investigation reported that the plan on designing of Street of Gaya had been processed with a focus laid on harmony of historical remains and cultural remains which are told to be natural components. However, the study also figured out that as long as relevant fields want to create different identity in each section and to efficiently deliver information, they should first prepare this smart design system to integrate each pieces of a streetscape as a whole.

• Journal of Korean Historical Folklife
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• no.33
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• pp.31-72
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• 2010

At first, I extract materials on folk religion from four encyclopedic literatures of late Chosun dynasty-Lee, Ji-Bong-Ryu-Seol(『芝峯類說』) by Soo-Kwang(李晬光), San-Lim-Kyung-Jae(『山林經濟』) by Hong, Man-Sun(洪萬選), Sung-Ho-Sa-Seol(『星湖僿說』) by Lee-Ik(李瀷), O-Ju-Yeon-Moon-Jang-Jun-San-Go(『五洲衍文長箋散稿』) by Lee, Kyu-Kyung(李圭景), and present these materials by tables. Second, I examined the contents and characters of these materials on folk religion. The conclusions from this research are as follows. ① There are common features and points of difference between these four encyclopedic literatures. One of common features are that all these four are encyclopedic works, but San-Lim-Kyung-Jae is more practical than another three. ② These encyclopedic literatures regard folk religion as a negative culture, because these literatures based on Confucianism. But they did not deny miraculous virtues of folk religion. ③ These encyclopedic literatures give us many informations on gods and spirits of Korean folk religion, i.e. city gods(城隍神)·Yup-Sin(업신)·spirits of disease, god Kim-Bu(金傅大王神)·god Jung-Duk-Yang(鄭得揚)·god of King Kuan-u(關王神)·god Bu-keun(付根神) etc. So I review these gods and spirits referenced in encyclopedic literatures. ④ These encyclopedic literatures show much interest in ghost in common. The reason of interest is that authors of these encyclopedic literatures are all scholars of Sung Confucianism and Sung Confucian was concern about ghost. The Sung Confucianism denied the ghost as personal being whom Korean folk religion regards to a kind of spirits. Instead of beliefs in ghost of folk religion, they insist on the ghost as Ki(氣), a kind of cosmic principle. But these encyclopedic literatures acknowledge some parts of folk religion's beliefs in ghost, because they admit the miraculous virtues of these parts. ⑤ There are many items on divination in these encyclopedic literatures. But they show dual attitude on divinations. The one is negative attitude to divinations on individual destiny and the other one is positive attitude to divinations on agriculture. ⑥ There are also many items on witchcrafts in these encyclopedic literatures. Through these items, I assumed pervasiveness of beliefs on witchcraft at that time. ⑦ Shamans, as religious specialist, are stand on a central position of Korean folk religion. So it is a matter of course that these encyclopedic literatures concerned on Korean shaman. As Confucians, authors of these encyclopedic literatures did not regards shamans as positive one. But they did not deny miraculous virtues of shamans. In spite of these encyclopedic literatures have negative view points to, and include false informations Korean folk religion, I would like to emphasis on importance of these encyclopedic literatures to understand Korean folk religions, especially Korean folk religions of late Yi Dynasty.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.827-833
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• 2023

CT(Computed Tomography) contrast agents are commonly used in general hospitals and university hospitals when taking radiographic examinations. The CT contrast medium contains a mixture of a substance called "Iodine", which absorbs radiation energy and makes it appear white in the CT image, further improving the image quality. In addition, the CT contrast agent, which moves like blood in the blood vessels, clearly differentiates it from muscle and water, so CT contrast agents are widely used in hospitals. These CT contrast agents absorb X-rays, but in order to absorb X-rays, they must have a high density or a high radiation absorption coefficient. Since the CT contrast agent is injected into the blood vessels, if the density is high, the blood vessels are strained and the patient is in shock. For this reason, it is necessary to match the density similar to that of water and always pay attention to side effects. In addition, the amount of CT contrast medium is adjusted according to the patient's body shape, and the remaining contrast medium is discarded. However, This study tried to find out the idea of recycling it as a radiation shielding material. Since the CT contrast medium has a high radiation absorption coefficient at a density similar to that of water, the amount to absorb radiation is adjusted, the amount of contrast medium and the amount of water are adjusted, and the amount of radiation absorbed is determined by mixing with water. In addition, a study was conducted to find out the result of the difference in radiation absorption in various ways by comparing the radiation quality coefficient and absorption coefficient with other substances or materials in an environmentally friendly method harmless to the human body by mixing CT contrast medium and water.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.65-77
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• 2023

Background: The shortage of dental hygienists as assistant is a great concern to dental clinics, while dental hygienists are rather pursuing the role of oral hygiene control and preventive treatments which is the main role for dental hygienists in the United States. The dental hygienist and dental assistant system in the United States can be a reference in these discussions. Methods: Educational requirements for licensure and work areas for dental hygienists and dental assistants were investigated through the information provided by the American Dental Association (ADA), American Dental Hygienists Association, National Board Dental Hygiene Examination (NBDHE), Dental Assistants Association of America (ADAA), and Dental Assistants National Board (DANB). Results: In the United States, each state has different systems, but in general, dental hygienists obtain licenses after completing 2~3 years of associate degree programs in dental hygiene after obtaining basic learning skills, and mainly perform tasks related to patient screening procedures, oral hygiene management and preventive care. Dental assistants can take the license test after completing a training course of 9~11 months to obtain a dental assistant certification. Additional expanded work typically requires passing state qualification tests, completing a training program, obtaining a degree, or gaining clinical experience for a certain period of time, depending on the state Conclusion: The scope of work of dental hygienists designated by the Medical Engineer Act and the Enforcement Decree in Korea includes both the work of dental hygienists and dental assistants in the United States, and if a dental assistant system like the United States is introduced to address the current shortage of dental assistants, institutional supplementation such as adjustment of the scope of work and expansion of the role of dental hygienists in oral hygiene management and prevention work is needed and in-depth discussion is necessary.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.151-160
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• 2023

Background: This study analyzed the differences in practice satisfaction, major, and willingness to work abroad among dental hygiene department students at K University in Gangwon-do based on their participation in international practicums. Methods: A survey was conducted on a total of 215 students through convenience sampling of dental hygiene students, and the final 214 responses were analyzed. General characteristics were examined. Major satisfaction and grades were measured on a 5-point Likert scale. And satisfaction with practice, intention to participate in international practicums, and employment were investigated by papers. Descriptive statistical analysis was performed on general characteristics using SPSS software (version 26.0). Due to the convenience sample, nonparametric analysis was used to determine satisfaction with practice and major according to general characteristics using the Mann-whitney U and Kruskal-wallis test. An independent samples t-test was conducted to determine the difference between practice satisfaction and major satisfaction depending on participation in international practicums, and Fisher's exact test was conducted to determine practice satisfaction, willingness to participate in overseas internships, and employment. Results: Concerning future participation in international clinical practicums, 66.7% of students who had previously participated in overseas training expressed willingness to engage again. 40.9% of those who had not participated showed no intention of participating, and there was a significant difference (p<0.05). Additionally, 76.2% of the participants expressed interest in overseas employment, with this difference also being statistically significant (p<0.05). Conclusion: It was confirmed that students' satisfaction with practice and major increased through participation in international practicums, and that they had a positive intention to work abroad and participate in overseas internship programs in the future.

• Korean Journal of Agricultural Science
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• v.13 no.1
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• pp.82-89
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• 1986

This experiment was carried out to determine the optimum freezing and thawing rates of the hamster embryos. The female hamsters were induced to superovulate by intraperitoneal injections of 30 i.u. PMSG and mated with males of the same strain of 4 days the PMSG injection. They were killed and embryos were flushed from the oviduct and uterine horn on 3 days after mating. Embryos were flushed with a modified Dulbecco's phosphate-buffered saline and equilibrated with 1.5 M-dimethylsulphoxide by a 3-step procedure. The freezing rates of the samples were $1^{\circ}C/min$ from room temperature to $-6^{\circ}C$ and the samples were seeded at $-6^{\circ}C$. After being held for 3 min at the seeding temperature, the rates were $0.3^{\circ}C/min$ from $-6^{\circ}C$ to $-35^{\circ}C$. From $-35^{\circ}C$ to $-70^{\circ}C$, the rates were divided into $0.1^{\circ}C/min$, $1^{\circ}C/min$ and $10^{\circ}C/min$, respectively. At $-70^{\circ}C$ the samples were plunged directly into liquid nitrogen. The samples were thawed at $4^{\circ}C/min$ and $12^{\circ}C/min$ from $-196^{\circ}C$ to $37^{\circ}C$, and for 2 min in $37^{\circ}C$ water bath, respectively. The average numbers of ovulation points and embryos recovered were 35.1 and 27.0 appearing 77.0% recovery rates. Eight cell embryos in the embryos recovered were 24.8. The survival rates of embryos according to the freezing rates were 55.5~67.7% at $0.1^{\circ}C/min$, 58.8~64.9% at $1^{\circ}C/min$ and 40.5~44.7% at $10^{\circ}C/min$, respectively. The survival rates at $10^{\circ}C/min$ were significantly low. The survival rates of embryos according to the thawing rates were 53.5% at $4^{\circ}C/min$, 53.7% at $12^{\circ}C/min$ and 59.1% in $37^{\circ}C$ water bath. The survival rates, in $37^{\circ}C$ water bath were slightly higher, but we did not find any differences among them. In conclusion, the best freezing rates of hamster embryos were $1^{\circ}C/min$ from the room temperature to $-6^{\circ}C/min$, $0.3^{\circ}C/min$ from $-6^{\circ}C/min$ to $-35^{\circ}C$ and $-0.1^{\circ}C/min$ or $1^{\circ}C/min$ from $-35^{\circ}C$ to $-70^{\circ}C$. The hamster embryos thawed for 2 min in $37^{\circ}C$ water bath showed the best survival rates.