• Restorative Dentistry and Endodontics
• /
• v.30 no.1
• /
• pp.49-57
• /
• 2005

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength to caries-affected dentin. Twenty one extracted human molars with occlusal caries extending into mid-dentin were prepared by grinding the occlusal surface flat. The carious lesions were excavated with the aid of caries detector dye. The following adhesives were applied to caries-affected dentin according to manufacturer's directions; $Scotchbond^{TM}$ Multi-Purpose in SM group, Adper Prompt $L-Pop^{TM}$ 1 coat in LP1 group, 2 coats in LP2 group, 3 coats in LP3 group, $Xeno^{(R)}$ III 1 coat in XN1 group, 2 coats in XN2 group. and 3 coats in XN3 group. After application of the adhesives, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the $1{\times}1\;mm^2$ sticks. The microtensile bond strength was determined. Each specimen was observed under SEM to examine the failure mode. Data were analyzed with one-way ANOVA. The results of this study were as follows; 1. The microtensile bond strength values were; SM ($14.38{\pm}2.01$ MPa), LP1 ($9.15{\pm}1.81$ MPa), LP2(14.08{\pm}1.75$ MPa), LP3 ($14.06{\pm}1.45$ MPa). XN1 (13.65{\pm}1.95$ MPa). XN2 ($13.98{\pm}1.60$) MPa, XN3 ($13.88{\pm}1.66$) MPa, LP1 was significantly lower than the other groups in bond strength (p < 0.05). All groups except LP1 were not significantly different in bond strength (p > 0.05). 2. In LP1, there were a higher number of specimens showing adhesive failure. Most specimens of all groups except LP1 showed mixed failure.

• Journal of Korean Society of Forest Science
• /
• v.34 no.1
• /
• pp.63-71
• /
• 1977

${\times}$Populus albaglandulosa has been needed optimum stand density according to various site and its wood usage. It is assumed that optimum stand density can be estimated by investigating of response of ${\times}$P. albaglandulosa to the light factor of stand. For that reason, the photosynthesis of ${\times}$Populus albaglandulosa grown under the controlled planting density was studied in relation to its leaf age by the aid of the Infrared gas analyzer. Rate of net photosynthesis was smaller in matured leaves than young leaves below $8^{\circ}C$, while, it was larger than young leaves above $8^{\circ}C$. Temperature for the maximum net photosynthesis of young leaves and old leaves was about $30^{\circ}C$ and $25^{\circ}C$ respectively. Saturated light intensity varied slightly as leaf age from 28 Klux to 35 Klux, but net photosynthesis rate in the range of light intensity showed deep differences. Old leaves marked the lowest rate, $1.6\;CO_2\;mg/dm^2/hr$, young leaves marked the medium rate, 1.7 to $2.2\;CO_2\;mg/dm^2/hr$, and matured leaves marked the most efficient photosynthesis, 2.9 to $3.5\;CO_2\;mg/dm^2/hr$. Young leaves of 5 days old had the highest light compensation point, while matured leaves of 35 days-old had the lowest point. Rates of dark respiration in both young leaves and old leaves were higher than that of matured leaves. Trees which were planted at space $80cm{\times}80cm$ showed productive assimilation function over the one-third of height where relative light intensity is 35%.

• Publications of The Korean Astronomical Society
• /
• v.36 no.3
• /
• pp.65-78
• /
• 2021

Jagyeokru, an automatic striking water clock described in the Sejong Sillok (Veritable Records of King Sejong) is essentially composed of a water quantity control device and a time-signal device, with the former controlling the amount or the flow rate of water and the latter automatically informing the time based on the former. What connects these two parts is a signal generating device or a power transmission device called the 'Jujeon' system, which includes a copper rod on the float and ball-racked scheduled plates. The copper products excavated under Gongpyeong-dong in Seoul include a lot of broken plate pieces and cylinder-like devices. If some plate pieces are put together, a large square plate with circular holes located in a zigzag can be completed, and at the upper right of it is carved 'the first scheduled plate (一箭).' Cylinder-like devices generally 3.8 cm in diameter are able to release a ball, and have a ginkgo leaf-like screen fixed on the inner axis and a bird-shaped hook of which the leg fixes another axis and the beak attaches to the leaf side. The lateral view of this cylinder-like device appears like a trapezoid and mounts an iron ball. The function of releasing a ball agrees with the description of Borugak Pavilion, where Jagyeokru was installed, written by Kim Don (1385 ~ 1440). The other accounts of Borugak Pavilion's and Heumgyeonggak Pavilion's water clocks describe these copper plates and ball releasing devices as the 'Jujeon' system. According to the description of Borugak Pavilion, a square wooden column has copper plates on the left and right sides the same height as the column, and the left copper plate has 12 drilled holes to keep the time of a 12 double-hours. Meanwhile, the right plate has 25 holes which represent seasonal night 5-hours (Kyeong) and their 5-subhours (Jeom), not 12 hours. There are 11 scheduled plates for seasonal night 5-hours made with copper, which are made to be attached or detached as the season. In accordance with Nujutongui (manual for the operation of the yardstick for the clepsydra), the first scheduled plate for the night is used from the winter solstice (冬至) to 2 days after Daehan (大寒), and from 4 days before Soseol (小雪) to a day before the winter solstice. Besides the first scheduled plate, we confirm discovering a third scheduled plate and a sixth scheduled plate among the excavated copper materials based on the spacing between holes. On the other hand, the width of the scheduled plate is different for these artifacts, measured as 144 mm compared to the description of the Borugak Pavilion, which is recorded as 51 mm. From this perspective, they may be the scheduled plates for the Heumgyeonggak Ongru made in 1438 (or 1554) or for the new Fortress Pavilion installed in Changdeokgung palace completed in 1536 (the 31^st year of the reign of King Jungjong) in the early Joseon dynasty. This study presents the concept of the scheduled plates described in the literature, including their new operating mechanism. In addition, a detailed model of 11 scheduled plates is designed from the records and on the excavated relics. It is expected that this study will aid in efforts to restore and reconstruct the automatic water clocks of the early Joseon dynasty.

• Journal of Mushroom
• /
• v.19 no.3
• /
• pp.166-175
• /
• 2021

In this study, monokaryons of "Heukari" (Pleurotus ostreatus) and "Hosan" (Pleurotus pulmonarius) were separated to remove the cell wall, and a cross-species protoplast fusion was developed through chemical treatment with polyethylene glycol. The protoplast-fused PF160306 and PF160313 strains have a culture period of 10 and 2 days shorter than that of the "Heuktari" and "Hosan" cultivars, respectively. Furthermore, the growth of the strains was faster than that of the existing cultivars. The yield was 135.9 g per bottle, which was approximately 8% higher than that of the commercially available "Hosan" cultivar; however, it was not statistically significant. A growth survey was conducted after treatment at five temperatures (15, 18, 21, 23, and 25℃). The growth of the strains accelerated with the increase in temperature. However, at 21℃, the yellow color of pileus was the brightest. Band pattern, assessed using URP Primer 7, was similar to that of the "Hosan" cultivar. The DPPH radical scavenging capacity and polyphenol content were 62.5% and 43.5 mg/mL, respectively, for "Sunjung" and 65.7% and 49.9 mg/mL, respectively, for PF160313. Furthermore, the antihypertensive activities of the "Sunjung" cultivar and PF160313 were similarly high at 74% and 75%, respectively. In conclusion, cross-species hybridization via the protoplast fusion technique can be used for obtaining primary data for mushroom breeding to develop new varieties. In addition, the protoplast fusion technique might aid in expanding the market for yellow mushrooms.

• Journal of the Korean earth science society
• /
• v.42 no.2
• /
• pp.201-220
• /
• 2021

The objective of this study is to increase awareness and interest regarding polar science and thereby aid in establishing the concept and future direction of polar literacy. To analyze the current status, textbooks based on the common school curriculum pertaining to polar topics were reviewed. Six countries that actively conduct polar science, namely Korea, France, Japan, Germany, the United States, and the United Kingdom, were chosen. Subsequently, 402 cases in 110 science and social studies (geography) textbooks of these countries were analyzed through both quantitative and qualitative methods. Based on the obtained results, the importance of polar research in geoscience education and the need for spreading awareness regarding polar research as an indicator of global environmental changes were examined. It was found that the primary polar topics described in the textbooks are polar glaciers, polar volcanism, solid geophysics, polar infrastructure, and preservation of geological resources and heritage. This demonstrates that the polar region is a field of research with important clues to Earth's past, present, and future environments and is also a good teaching subject for geological education. However, an educational approach is needed for systematically laying emphasis on polar research. The implications of this study are manifold, such as the establishment of a cooperative system between polar scientists and educators, extraction of core concepts for polar literacy and content reconstruction, discovery of new polar topics associated with the curriculum, diversification of forms of presentation in textbooks, and development of an affective image that is based on correct cognitive understanding. Furthermore, through the continuance of polar topics in textbooks, students can improve their awareness regarding polar literacy and polar science culture, which in turn will serve as the driving force for sustainable polar research in the future.

• 한국노년학
• /
• v.38 no.4
• /
• pp.1057-1081
• /
• 2018

This study analyzed the case of elderly care cluster in Gwangjin-gu to explore the possibilities of social economy as a provider of community-based social services. Community-based means the approach by which community organizations build a voluntary and collaborative network to enhance collective problem-solving abilities. Therefore, it is very likely that the social economy that emphasizes people, labor, community, and democratic principles can contribute to community-based social services. This study analyzed social economic network by using four characteristics of social economy suggested by OECD community economy and employment program as an analysis framework. The results of this study are as follows: First, it is found that social economy would hardly supply community-based social services through network cooperation because of a large variation in community identity, investment to new product, and labor protection. Second, community users are not the consumers of the social economy and the products of the social economy stay in market products only for the organizations in social economy. In order to create good services that meet the needs of residents, community development approaches are required at the same time. The importance of community space where local residents and social economy meet is derived. Third, public support such as purchasing support has weakened the ecosystem of social economy by making the distinction between public economy and social economy more obscure. On the other hand, public investment in community infrastructure is an indirect aid to social economy to communicate with residents and to promote good supply and consumption. In the end, community-based social services need a platform where the social economy and the people meet. This type of public investment can create the ecosystem of the social economy.

• Korean Journal of Heritage: History & Science
• /
• v.47 no.1
• /
• pp.66-81
• /
• 2014

Burnt down during the Imjin War(壬辰倭亂) of 1592, Gyeongbokgung Palace(景福宮) remained in ruins until 1865, when in the second year of King Gojong's(高宗) reign, reconstruction work began. At the time, a royal protocol(uigwe, 儀軌) for the reconstruction was not produced. Instead, the Gyeongbokgung Palace Construction Diary(Gyeongbokgung yeonggeon ilgi, 景福宮營建日記) records the reconstruction process from June to September of 1865. The contents of this diary reveal that the stone used in the construction was obtained from Ganghwa(江華), the Yeongpung field(映楓亭) just beyond Dongdaemun, and Samcheongdong(三淸洞), among other sites. In addition, selected stone remaining from the original Gyeongbokgung Palace site - such as that from the palace astronomical observatory(ganuidae, 簡儀臺) - as reused, while a number of buildings and stonework from Gyeonghuigung Palace(慶熙宮) were moved to Gyeongbokgung Palace. As a result, a number of $17^{th}$ and $18^{th}$ century stonework are currently located at Gyeongbokgung Palace. The Gyeongbokgung Palace Construction Diary contains a record indicating that the bronze dragon(靑銅龍) excavated from the lotus pond at the palace's Gyeonghoeru Pavilion(慶會樓) was created by special technician byeolganyeok(別看役) Kim Jae-su(金在洙) in 1865 for the symbolic purpose of protecting the palace from fire. The diary also reveals that among Kim Jae-su and the other special technicians(byeolganyeok) tasked with the installation and oversight of the palace stonework was Lee Se-ok(李世玉) - aid to have created the haechi statue at Gwanghwamun Gate. This indicates that there were men of court painter(hwawon, 畵員) background among the construction special technicians(byeolganyeok). Moreover, the diary records the names of the stoneworkers(seokjang, 石匠) who worked under these special technicians to actually carve the stonework. These included Jang Seong-bok(張聖福), who participated in the creation of the Geunjeongjeon Hall(勤政殿); and Kim Jin-myeong(金振明), who took part in the construction of Gwanghwamun Gate(光化門). Based on these results, it is possible to identify a number of special iconographic features of the scale-covered animal form(insuhyeong, 鱗獸形) auspicious animal statues at Gyeongbokgung Palace. These include a protruding mouth and large nose, formalized ears, and a mane along the back. Comparing these iconographic features with those found in the stonework of Joseon tombs makes it clear that these palace statues were created in the latter half of the $19^{th}$ century - the period corresponding to Gojong's palace reconstruction. This study was able to confirm that this iconography was taken up by the Gyeongbokgung Palace construction special technicians(byeolganyeok) and stoneworkers(seokjang) as they worked on tomb stonework earlier in their careers.

• Journal of agricultural medicine and community health
• /
• v.44 no.1
• /
• pp.28-38
• /
• 2019

Objectives: We searched and reviewed the literature including the laws or acts, statistics, guidelines, papers and conference proceedings related to home visit nursing care in South Korea. Method: We searched and reviewed the literature including the laws or acts, statistics, guidelines, papers and conference proceedings related to home visit nursing care in Korea. Results: There are three types of home care nursing in Korea. Public health center provides home visit nursing to vulnerable population by registered nurses for free, based on community health act in public health center. As of 2017, 1,261,208 people were enrolled in the visiting health program of public health center. Health behavior and disease management has been improved and showed having cost-benefit effect among the enrolled people in visiting health program. Visiting nursing care in long-term care services is provided by registered nurses or nurse aid, based on long-term care act. The cost is paid as the unit price according to service time. 1,095,764 older people used long-term care services in 2017, only 0.2% of total cost used for home visiting nursing. Even though the number of user of home visiting nursing, it was reported that users spent less medical cost and hospitalized shorter. Hospital-based home care nursing is provided to patients and their families under the prescription of a doctor by family nurse specialists who are employed by medical institute based on medical law. Four hundred sixty family nurse specialists worked for hospital-based home care nursing and hospital-based home care services accounted for 0.038% of total medical expenses in 2017. Conclusion: Even though home visit nursing care services are different in aspect of legal basis, personnel, running institutes, and cost basis, home visit nursing care showed cost-benefit effect and good health outcomes. In order to advance home visit nursing care, the integrated home visiting care, improvement of working condition, and revision of legal basis should be considered.

• Journal of Intelligence and Information Systems
• /
• v.25 no.3
• /
• pp.63-88
• /
• 2019

The goal of this paper is to investigate changes in North Korea's domestic and foreign policies through automated text analysis over North Korea represented in South Korean mass media. Based on that data, we then analyze the status of text mining research, using a text mining technique to find the topics, methods, and trends of text mining research. We also investigate the characteristics and method of analysis of the text mining techniques, confirmed by analysis of the data. In this study, R program was used to apply the text mining technique. R program is free software for statistical computing and graphics. Also, Text mining methods allow to highlight the most frequently used keywords in a paragraph of texts. One can create a word cloud, also referred as text cloud or tag cloud. This study proposes a procedure to find meaningful tendencies based on a combination of word cloud, and co-occurrence networks. This study aims to more objectively explore the images of North Korea represented in South Korean newspapers by quantitatively reviewing the patterns of language use related to North Korea from 2016. 11. 1 to 2019. 5. 23 newspaper big data. In this study, we divided into three periods considering recent inter - Korean relations. Before January 1, 2018, it was set as a Before Phase of Peace Building. From January 1, 2018 to February 24, 2019, we have set up a Peace Building Phase. The New Year's message of Kim Jong-un and the Olympics of Pyeong Chang formed an atmosphere of peace on the Korean peninsula. After the Hanoi Pease summit, the third period was the silence of the relationship between North Korea and the United States. Therefore, it was called Depression Phase of Peace Building. This study analyzes news articles related to North Korea of the Korea Press Foundation database(www.bigkinds.or.kr) through text mining, to investigate characteristics of the Kim Jong-un regime's South Korea policy and unification discourse. The main results of this study show that trends in the North Korean national policy agenda can be discovered based on clustering and visualization algorithms. In particular, it examines the changes in the international circumstances, domestic conflicts, the living conditions of North Korea, the South's Aid project for the North, the conflicts of the two Koreas, North Korean nuclear issue, and the North Korean refugee problem through the co-occurrence word analysis. It also offers an analysis of South Korean mentality toward North Korea in terms of the semantic prosody. In the Before Phase of Peace Building, the results of the analysis showed the order of 'Missiles', 'North Korea Nuclear', 'Diplomacy', 'Unification', and ' South-North Korean'. The results of Peace Building Phase are extracted the order of 'Panmunjom', 'Unification', 'North Korea Nuclear', 'Diplomacy', and 'Military'. The results of Depression Phase of Peace Building derived the order of 'North Korea Nuclear', 'North and South Korea', 'Missile', 'State Department', and 'International'. There are 16 words adopted in all three periods. The order is as follows: 'missile', 'North Korea Nuclear', 'Diplomacy', 'Unification', 'North and South Korea', 'Military', 'Kaesong Industrial Complex', 'Defense', 'Sanctions', 'Denuclearization', 'Peace', 'Exchange and Cooperation', and 'South Korea'. We expect that the results of this study will contribute to analyze the trends of news content of North Korea associated with North Korea's provocations. And future research on North Korean trends will be conducted based on the results of this study. We will continue to study the model development for North Korea risk measurement that can anticipate and respond to North Korea's behavior in advance. We expect that the text mining analysis method and the scientific data analysis technique will be applied to North Korea and unification research field. Through these academic studies, I hope to see a lot of studies that make important contributions to the nation.

• The Korean Journal of Air & Space Law and Policy
• /
• v.33 no.2
• /
• pp.291-314
• /
• 2018

In recent 3 years, Korea's low-cost airlines have expanded their areas of passenger transportation not only to domestic market but also to Japan, China, Southeast Asia and US territory as a total of 6 companies (8 airlines including small air operation business carriers). Currently, three more airlines have filed for air transportation business certification as future low-cost carriers, and this expansion is expected to continue. To cope with the aggressive airline operations of domestic and foreign low-cost carriers and to enhance their competitiveness, each low-cost airline is taking a number of strategies for promoting cabin service. Therefore, the workload of the cabin crew is increased in proportion to the expansion, and the fatigue directly connected with the safety task performance is increased. It is stipulated in the Enforcement Regulations of the Korea Aviation Safety Act that at minimum, one cabin crew is required per 50 passenger seating capacity, and all low cost carriers are boarding only the minimum cabin crew. Sometimes it is impossible for them to sit in a floor level emergency exit for evacuation, which is the main task of the cabin crew, and this can cause confusion among evacuating passengers in the event of an emergency. In addition, if one of the minimum cabin crew becomes incapacitated due to an injury or the like, it will become a serious impediment in performing emergency evacuation duties. Even in the normal situation, since it will be violating the Act prescription on the minimum cabin crew complement, passengers will have to move to another available airline flights, encountering extreme inconvenience. Annex 6 to the Convention on International Civil Aviation specifies international standards for the determination of the minimum number of cabin crew shall be based only on the number of passenger seats or passengers on board for safe and expeditious emergency evacuation. Thereby in order to enhance the safety of the passengers and the crew on board, it is necessary to consider the cabin crew's fatigue that may occur in the various job characteristics (service, safety, security, first aid)and floor level emergency exit seating in calculating the minimum number of cabin crew. And it is also deemed necessary for the government's regulatory body to enhance the cabin safety for passengers and crew when determining the number of minimum cabin crew by reflecting the cabin crew's workload leading to their fatigue and unavailability to be seated in a floor level emergency exit on low cost carriers.