• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.517-534
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• 2021

Hydrogen fuel is emerging as an new energy source to replace fossil fuels in that it can solve environmental pollution problems and reduce energy imbalance and cost. Since hydrogen is eco-friendly but highly explosive, there is a high concern about fire and explosion accidents of hydrogen fueled vehicles. In particular, in semi-enclosed spaces such as tunnels, the risk is predicted to increase. Therefore, this study was conducted on the applicability of the equivalent TNT model and the numerical analysis method to evaluate the hydrogen explosion pressure in the tunnel. In comparison and review of the explosion pressure of 6 equivalent TNT models and Weyandt's experimental results, the Henrych equation was found to be the closest with a deviation of 13.6%. As a result of examining the effect of hydrogen tank capacity (52, 72, 156 L) and tunnel cross-section (40.5, 54, 72, 95 m²) on the explosion pressure using numerical analysis, the explosion pressure wave in the tunnel initially it propagates in a hemispherical shape as in open space. Furthermore, when it passes the certain distance it is transformed a plane wave and propagates at a very gradual decay rate. The Henrych equation agrees well with the numerical analysis results in the section where the explosion pressure is rapidly decreasing, but it is significantly underestimated after the explosion pressure wave is transformed into a plane wave. In case of same hydrogen tank capacity, an explosion pressure decreases as the tunnel cross-sectional area increases, and in case of the same cross-sectional area, the explosion pressure increases by about 2.5 times if the hydrogen tank capacity increases from 52 L to 156 L. As a result of the evaluation of the limiting distance affecting the human body, when a 52 L hydrogen tank explodes, the limiting distance to death was estimated to be about 3 m, and the limiting distance to serious injury was estimated to be 28.5~35.8 m.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.164-178
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• 2022

Uncertainties in weather forecasts would affect the reliability of yield prediction using crop models. The objective of this study was to compare uncertainty in crop yield prediction caused by the use of the weather forecast data. Daily weather data were produced at 10 km spatial resolution using W eather Research and Forecasting (W RF) model. The nearest neighbor method was used to downscale these data at the resolution of 5 km (W RF5K). Parameter-elevation Regressions on Independent Slopes Model (PRISM) was also applied to the WRF data to produce the weather data at the same resolution. W RF5K and PRISM data were used as inputs to the CROPGRO-SOYBEAN model to predict crop yield. The uncertainties of the gridded data were analyzed using cumulative growing degree days (CGDD) and cumulative solar radiation (CSRAD) during the soybean growing seasons for the crop of interest. The degree of agreement (DOA) statistics including structural similarity index were determined for the crop model outputs. Our results indicated that the DOA statistics for CGDD were correlated with that for the maturity dates predicted using WRF5K and PRISM data. Yield forecasts had small values of the DOA statistics when large spatial disagreement occured between maturity dates predicted using WRF5K and PRISM. These results suggest that the spatial uncertainties in temperature data would affect the reliability of the phenology and, as a result, yield predictions at a greater degree than those in solar radiation data. This merits further studies to assess the uncertainties of crop yield forecasts using a wide range of crop calendars.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.394-399
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• 2022

This study was conducted to estimate hazardous heavy metal content, including lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in 120 collagen products currently marketed in Korea. Hg concentration was analyzed by a gold amalgamation method using a mercury analyzer, while concentrations of Pb, Cd, and As were analyzed by ICP-OES. The average Pb concentration was 0.097 mg/kg. For comparison, respective average concentrations were 0.108 mg/kg, 0.084 mg/kg, 0.131 mg/kg, and 0.149 mg/kg in functional health foods, other processed products, beverages, and fruit/vegetable processed products. The average concentration of Cd was 0.026 mg/kg. All products in which Cd was detected were functional health foods. The average concentration of As was 0.097 mg/kg, with respective average concentrations of 0.091 mg/kg, 0.133 mg/kg, and 0.086 mg/kg in functional health foods, other processed products, and fruit/vegetable processed products. The average Hg concentration was 0.0025 mg/kg, with respective average concentrations of 0.0012 mg/kg, 0.0028 mg/kg, 0.0013 mg/kg, and 0.0031 mg/kg in functional health foods, other processed products, fruit/vegetable processed products, and candies respectively. Heavy metal levels in beverages and candy products with set heavy metal standards were below the set standards. Even products without regulatory standards were found to be relatively safe compared with heavy metal standards set for domestic and foreign foods.

• Journal of the Korean Orthopaedic Association
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• v.56 no.1
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• pp.51-60
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• 2021

Purpose: Radiocarpal dislocation (RCD), which is caused by high-energy trauma, often involves radial styloid fractures and short radiolunate ligament (SRLL) injuries. Although SRLL injuries may occur as a simple rupture at the attachment site of radius, it may occur with a relatively large avulsed-fragment in the volar rim of the lunate facet of the radius. This study aimed to differentiate the injury type of SRLL and assess the differences in the treatment results depending on the treatment methods that have been applied in RCD with radial styloid fractures. Materials and Methods: Eighteen patients managed surgically with RCD were enrolled in this study. The patients were classified as Group 1 and Group 2 by using the Dumontier method. In this study, Group 2 was subdivided into 2A (purely ligamentous or small avulsion fracture of the volar rim of lunate facet) and 2B (large avulsed-fragment enough to internal fixation) according to the injury type of SRLL. Groups 2A and 2B were treated with direct repair and screw fixation, respectively. Pain, range of motion of the wrist joint, grip strength, and complications on final radiographs were examined. The outcomes were evaluated using patient-rated wrist evaluation (PRWE), and modified Mayo wrist score (MMWS). Results: All patients were Group 2 (six and twelve patients in 2A and 2B, respectively). The mean flexion to extension arch recovered 79%,and the mean grip strength was 72.9% of the uninjured side. Group 2A showed better recovery in extension, flexion and pronation than Group 2B, but there was no difference in radial deviation, ulnar deviation, supination, grip strength and pain. No differences in the PRWE and MMWS were observed between two groups. Complications included traumatic arthritis in seven patients and residual instability in five patients. Conclusion: When the SRLL was injured, the involvement of a large avulsion fracture on the anterior plane of the radiolunate did not affect the test results. On the other hand, it should be observed cautiously because avulsion fractures tend to disturb the joint's reduction through rotation or displacement. In addition, anatomical reduction and sturdy internal fixation are important for restoring the function of the SRLL.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.491-497
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• 2022

In this study, we tried to secure basic data to create an environment necessary for distance learning through a survey on professor demand. Among the 184 full-time faculty members of the university, 73 (39.89%) respondents in 2021 and 87 (47.28%) in 2022 were included. As a result of the research on professor demand, in the 2021 school year, 27 people (37%) were classified as LMS improvement items when checking attendance, 38 people (23.3%) were pin-mics as content development support items, and 26 people (35.6%), 33 people (45.2%) of GOM Mix and 25 people (34.2%) of the distance education support center wanted to learn video editing program as the item of video editing program they are currently using. In the 2022 school year, 27 people (31.03%) said mobile upgrade as an LMS improvement item, 52 people (59.8%) of pin-microphone as a content development support item, 33 people (37.9%), but currently using the content creation intention using a studio. As for the video editing program they are working on, 47 people (54%) of GOM Mix Pro and 23 people (26.4%) of the distance education support center want to learn content creation method. In addition, the intention to produce content using the studio for the 2021 and 2022 academic year and the desired educational topic of the distance education support center in the future appeared insignificant (p > 0.05). In this distance education support center, we are working to solve the class of LMS attendance, upgrade mobile, and plan to distribute pin microphones. We are planning to increase the usability of the studio and provide training on how to use video editing programs and how to create video content. In order for a smooth class to take place in a university distance class, the university authorities should seek ways to support the instructor so that he/she does not have difficulties in performing his/her role as a teaching designer, such as setting learning goals, organizing and organizing content, motivating learning, and establishing effective class participation plans. there is a need

• Journal of Korean Home Economics Education Association
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• v.34 no.1
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• pp.35-57
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• 2022

This study developed an 'Eco-friendly Clothing Life Cycle' class applying gamification. And the effect of and learners' satisfaction on the class were examined after implementation. The developed class was applied to 40 sophomore students from "A" high school in Gyeonggi-do from February 3, 2022, to February 10, 2022, in a total of 4 sessions. The class was conducted in the stages of production-distribution-consumption-disposal, and was conducted in a way that a mission is solved after learning in Gather Town. It is designed so that learners continuously repeat learning until they accomplish the mission. The learners completed pre-class and post-class questionnaires. And a focus group interview was conducted with a randomly selected group of three learners. According to the pre-/post-class test comparison, the gamification class on the theme of "Eco-friendly Clothing Life Cycle" was found not to have a significant effect on learners' immersion or self-directed learning attitudes. However, in the case of the learners with high levels of non-immersion tendency, the level of immersion in the class increased, and the satisfaction level was positively associated with the level of immersion and self-directed attitude. Learners expressed 'concern' and 'expectation' about the gamification class, and said that although the developed class was using a 'new teaching method', 'appropriate use' was necessary. And learners were evaluated this class as a 'student-centered class' and acknowledged that it allowed 'self-directed learning'. The teacher who implemented the class said that this class was more effective in attracting students' expectations and interests compared to the conventional classes, and that the class in the meta-verse environment was perceived as a new type of class in the non-face-to-face era. The teacher also mentioned that when applied to the actual educational field, a detailed design is needed that allows the learners to proceed smoothly, and the role of the teacher in the class was more important. And the teacher also mentioned that the class should be properly designed so that the expectations given by the 'game' do not obscure the essence of the class.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.40 no.2
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• pp.34-43
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• 2022

This study compared the characteristics of cultural heritage in China and Vietnam, which have developed in the relationship of mutual geopolitical and cultural influence in history, and the following conclusions were made. First, the definition of cultural heritage in China and Vietnam has similar meanings in both countries. In the case of cultural heritage classification, both countries introduced the legal concept of intangible cultural heritage through UNESCO, and have similarities in terms of intangible cultural heritage. Second, while China has separate laws for managing tangible and intangible cultural heritages, Vietnam integrally manages the two types of cultural heritages under a single law. Vietnam has a slower introduction of the concept of cultural heritage than China, but it shows high integration in terms of system. Third, cultural heritages in both China and Vietnam are graded, which is applied differently depending on the type of heritage. The designation method has a similarity in which the two countries have a vertical structure and pass through steps. By restoring the value of heritage and complementing integrity through such a step-by-step review, balanced development across the country is being sought through tourism to enjoy heritage and create economic effects. Fourth, it was confirmed that the cultural heritage management organization has a central government management agency in both countries, but in China, the authority of local governments is higher than that of Vietnam. In addition, unlike Vietnam, where tangible and intangible cultural heritage are managed by an integrated institution, China had a separate institution in charge of intangible cultural heritage. Fifth, China is establishing a conservation management policy focusing on sustainability that harmonizes the protection and utilization of heritage. Vietnam is making efforts to integrate the contents and spirit of the agreement into laws, programs, and projects related to cultural heritage, especially intangible heritage and economic and social as a whole. However, it is still dependent on the influence of international organizations. Sixth, China and Vietnam are now paying attention to intangible heritage recently introduced, breaking away from the cultural heritage protection policy centered on tangible heritage. In addition, they aim to unite the people through cultural heritage and achieve the nation's unified policy goals. The two countries need to use intangible heritage as an efficient means of preserving local communities or regions. A cultural heritage preservation network should be established for each subject that can integrate the components of intangible heritage into one unit to lay the foundation for the enjoyment of the people. This study has limitations as a research stage comparing the cultural heritage system and preservation management status in China and Vietnam, and the characteristic comparison of cultural heritage policies by type remains a future research task.

• Journal of Food Hygiene and Safety
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• v.37 no.4
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• pp.260-270
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• 2022

In this study, we tested for pesticide residues in 114 samples representing 20 different types of fruit circulating in Gyeonggido. A total of 341 pesticides were identified via a multi-residue method using GC-NPD, GC-ECD, GC-MSMS, and LC-MSMS. In whole fruit, pesticides were detected in 48 cases, with a concentration range of 0.0025-0.1663 mg/kg. In the peels, pesticides were detected in 85 cases, with a concentration range of 0.0026-4.7185 mg/kg and a higher average concentration than was found in whole fruit. In the pulp, pesticides were detected in 8 cases, with a concentration range of 0.0021-0.0993 mg/kg. In most of the peels, pesticides were detected below MRL. In the kiwi peel, deltamethrin (with an MRL of 0.05 mg/kg) was detected at 0.1020 mg/kg. Since MRLs are applied to whole fruit, these levels are not unsuitable for ingestion. However, washing is recommended before ingestion to promote healthier and safer inclusion of the peel in the diet. Continuous monitoring of the peel and pulp is indicated.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.2
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• pp.166-181
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• 2023

The purpose of this study is to examine the change and appropriateness of inquiry tendency in elementary science textbooks by national curriculum period by comparing previous researches that reported Romey's Involvement Index in the science textbook and other subject textbooks. The results of the study are as follows: First, for the text index (T), the value of science textbooks by curriculum tends to continue to decline overall. The value of science textbook based on the 3rd curriculum is judged to be extremely inquiry oriented and the value of the textbooks based on the 2007 and 2015 revised curriculum are the values judged as somewhat authoritative textbook and as a textbook at the appropriate level of inquiry, respectively. There is no significant difference compared to the T values of other subject textbooks since the 2007 revised curriculum; Second, the index of figures and diagrams in the text (FD) of science textbooks also continues to decline by curriculum periods. In particular, the FD value of science textbook of the 2015 revised period is judged to be a authoritative textbook, which is lower than the value of other subject textbooks; Third, in the case of the activity index (A), it gradually decreases from the third curriculum to the 2015 revised curriculum, but it is judged as textbooks suitable for inquiry. However, after the 7th curriculum, the value of A is generally lower than those of other subject textbooks; Fourth, for the index of the questions at the ends of chapters (Q), the value of Q is reported to be extremely limited compared to the aforementioned three indices(T, FD and A), which may be mainly due to differences in the composition of science textbooks by curriculum period.

• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.57-71
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• 2015

This study was conducted to develop the fertigation system with a peristaltic hose pump and brushless DC motor. The fertigation system was consisted of sensor, main controller, motor control unit, peristaltic pump, water supply pump, control panel, and filter. The peristaltic pump discharges liquid by squeezing the tube with rollers. Rollers attached to the external circumference of the rotor compresses the flexible tube. The fluid is contained within a flexible tube fitted inside a circular pump casing. The developed fertigation system has no mixing tank but instead injects directly a concentrated nutrient solution into a water supply pipe. The revolution speed of the peristaltic pump is controlled by PWM (Pulse width modulation) method. When the revolution speed of the peristaltic pump was 300rpm, the flow rate of the 3.2, 4.8, 6.3mm diameter tube was 202, 530, 857mL/min, respectively. As increasing revolution speed, the flow rate of the peristaltic pump linearly increased. As the inner diameter of a tube larger, a slope of graph is more steep. Flow rate of three roller was more than that of four roller. Flow rate of a norprene tube with good restoring force was more than that of a pharmed tube. As EC sensor probe was installed in direct piping in comparison with bypass piping showed good performance. After starting the system, it took 16~17 seconds to stabilize EC. The maximum value of EC was 1.44~1.7dS/m at a setting value of 1.4dS/m. The developed fertigation system showed ±0.06dS/m deviation from the setting value of EC. In field test, Cucumber plants generally showed good growth. From these findings, this fertigation system can be appropriately suitable for fertigation culture for crops.