• Korean Chemical Engineering Research
• /
• v.60 no.3
• /
• pp.414-422
• /
• 2022

The objective of this work was to investigate the feasibility of acid-catalyzed hydrothermal fractionation for maximum solubilization of the hemicellulosic portion of two typical agricultural residues. The fractionation conditions converted into combined reaction severity (CS) in the range of 1.2-2.9 was used to establish a simple reaction criteria at glance. The hemicellulosic sugar yield of 56.6% was shown when rice straw was fractionated at the conditions at the conditions; 160 ℃ of temperature 0.75% (w/v) of H₂SO₄, 20 min of reaction time, 1:15 solid/liquid ratio. The hemicellulosic sugar yield of 83.0%, however, was achieved when barley straw was fractionated at the conditions at the conditions; 150 ℃ of temperature 0.75% (w/v) of H₂SO₄, and 15 min of reaction time, 1:10 solid/liquid ratio. For barley straw, acid-catalyzed hydrothermal fractionation could be effectively performed. After the fractionation process, the remaining fractionated solids were 48.5% and 57.5% from raw rice and barley straws, respectively. The XMG contents in the solid residues decreased from 17.3% and 17.6% to 6.0% and 2.6%, which corresponded to 16.7% and 8.5% on the basis of the raw straws, respectively. In another way, only 5.6% of cellulose and 8.5% of XMG were lost due to excessive decomposition during the acid-catalyzed hydrothermal fractionation of barley straw, compared to cellulose and XMG losses of 6.4% and 26.6% in rice straw. Hemicellulosic sugars from the rice straw were considered more over-decomposed due to the somewhat higher reaction severity at the acid-catalyzed hydrothermal fractionation.

• Journal of Navigation and Port Research
• /
• v.46 no.4
• /
• pp.297-302
• /
• 2022

An exothermic oil absorbent sheet with calcium chloride crystals can be fabricated, by dipping a clean polypropylene fabric in calcium carbonate and hydrochloric acid solution and drying it. The exothermic oil absorbent sheet applied to the seawater surface, releases heat by the dissociation of calcium chloride. The dissociation heat liquefies the solidified low-sulfur fuel oil at a low temperature, and converts it to a state at which it can be absorbed. The optimum mole concentrations of calcium carbonate and hydrochloric acid required for the exothermic oil absorbent sheet, are 0.25 M and 0.5 M, respectively. The oil absorption capacity of the exothermic oil absorbent sheet for low sulfur fuel oil depends on the seawater temperature. But, it is highly excellent at 4.5-7.08 g/g at 10℃, the average seawater temperature during the winter in Korea. The exothermic oil absorbent sheet is an excellent alternative in absorbing low-sulfur fuel oil in winter and removing it from seawater.

• Korean Association of Arts Management
• /
• no.56
• /
• pp.243-274
• /
• 2020

Maker culture in Korea began to receive public attention after the 2012 Maker Fair Seoul. Central and local governments took note of this trend and subsumed makers' culture into its policy domains such as Creative Industry, Creative Cities, 4th Industrial Revolution, and the all-encompassing Creative Economy. Creative Economy was a public policy discourse formed in the public sector for the purpose of overcoming economic depression and revitalizing the economy. Under Creative Industry and Creative Economy, creativity and culture/arts are deemed indispensable but at the same time objectified and alienated as their ultimate value are recognized only as the basis for economic production. In this article, makers' culture itself goes through the same process of objectification and alienation that creativity and culture/arts suffered as the relevant policies were pursued under Creative Economy. The authors attempted to corroborate this through the case of Makercity Sewoon, and found that the Seoul City's urban development plan surrounding Sewoon Plaza proceeded in a direction destructive to the local technological ecosystem and therefore conflicts with the pronounced goal of leading 4th Industrial Revolution by encouraging and nurturing makers' culture. Makercity Sewoon, although packaged in a discourse of Creative Economy and Creative City, betrayed the same problem of alienating arts/culture and labor that the previous discourse showed.

• Korean Journal of Ecology and Environment
• /
• v.55 no.2
• /
• pp.111-119
• /
• 2022

The occurrence of cyanobacterial blooming and the contaminant sources were analyzed in the downstream of Jecheon Stream, a tributary of Chungju Reservoir. The concentrations of chlorophyll a at the Myungseo Fishing Point (GPS; 37°03'25.5"N, 128°03'13.6"E) were 399.2 and 184.8 mg m^-3 on October 18, 2015 and September 25, 2016, respectively, and the concentrations of total microcystins, a cyanobacterial toxin mainly produced by Microcystis, were 124.09 and 79.71 ㎍ L^-1, respectively. The occurrence of cyanobacterial blooming at the downstream of Jecheon Stream was closely related to the water level of Chungju Reservoir. The cyanobacterial blooming occurred after the increase of water level in Chungju Reservoir, when the water body stagnated. As a result of analyzing National Water Quality Monitoring Data of the upper region of Jecheon Stream, the main source of pollutant was Jangpyeong Stream, the tributary of Jecheon Stream, and the discharge water from Jecheon Wastewater Treatment Plant located in Jangpyeong Stream was considered to be the most important source of contaminant.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.33 no.3
• /
• pp.172-178
• /
• 2022

Background and Objectives Injection laryngoplasty is a common method for treatment of unilateral vocal fold paralysis. Unilateral vocal fold paralysis has various causes, including idiopathic, infection, stroke, neurologic condition, surgery and nerve invasion by cancer. To the knowledge of the authors, there was no study on the relationship between the causes of vocal cord paralysis and the outcome of injection laryngoplasty. Therefore, we tried to investigate the difference in the outcomes of injection laryngoplasty between vocal cord paralysis after surgery group and nerve invasion by cancer group. Materials and Method A retrospective analysis was performed for 24 patients who underwent vocal cord injection due to unilateral vocal cord paralysis caused by surgery or nerve invasion by cancer. The objective quality of the voice was assessed by acoustic voice analysis with the Multi-Dimensional Voice Program. Results Both group showed an improvement of fundamental frequemcy (F0), jitter percent, shimmer (percent), and noise to hearmonic ratio (NHR) after injection laryngoplasty. The vocal cord paralysis due to nerve invasion group showed more improvement in both the mean and median value of F0, shimmer percent and NHR than the vocal cord paralysis due to surgery group, but there was not statistically significant. Conclusion Our study did not show a statistically significant difference in outcome between vocal cord paralysis due to cancer invasion group and surgery group, but statistically tendency was suggested. The vocal cord paralysis due to nerve invasion group showed more improvement in both the mean and median value of acoustic voice analysis than surgery group.

• 한국체육학회지인문사회과학편
• /
• v.51 no.3
• /
• pp.273-284
• /
• 2012

There is a large body of literature that studies serious leisure participants in a wide range of activities. By comparison, casual leisure has received scant attention, bearing few empirical studies. And serious leisure is often cast in an superior role in comparison with casual leisure for optimally healthy or beneficial leisure. The purpose of this study is to investigate the psychological functioning of 'casual leisure-serious leisure'. Especially, we pay more attention to reveal the positive functioning of casual leisure. It draws findings from the data of 291 university students. The results are as follows. First, in comparison with 'casual leisure group', 'serious leisure group' was showed a higher significant increase in leisure related functioning(leisure satisfaction and leisure benefits such as physical health, relationship and self-controlibility). However, There is no significant inter-group differences in 'self-life functioning variables(positive·negative self-esteem, happiness, quality of life)'. It implies even though serious leisure has more relation to positive leisure experiences, people maintain and enhance their self-esteem and experience satisfaction and happiness of their entire lives through casual leisure participation as much as serious leisure.

• The Korean Journal of Coaching Psychology
• /
• v.4 no.1
• /
• pp.21-46
• /
• 2020

The purpose of this study was to verify the effectiveness of the coaching program on enhancing Grit. In addition, we wanted to examine the positive effects of Grit improvement on career preparation behavior and career attitude. Participants in this program were recruited from college students in a women university located in Seoul. They were assigned to both experimental and control group, 10 for each group. The program was conducted once a week for 90 minutes per session and a total of eight sessions were implemented. Pre-test, post-test, and follow-up test were conducted before, after, and 2 weeks after the coaching program. The results showed grit increased significantly for the experimental group, but not for the control group. Both the level of career preparation behavior and career attitude were also significantly improved only for the experimental group. In addition, the effect of the program was maintained for two weeks. Finally, the limitations of this study and suggestions for subsequent studies are described.

• Journal of Industrial Convergence
• /
• v.20 no.12
• /
• pp.11-25
• /
• 2022

In this study, we want to verify the factors that affect the intention to switch to a supply chain management information system applied with blockchain. To this end, variable selection and research model were constructed through the review of previous studies, and empirical analysis was conducted using the TOE framework and PPM model. The effects of Push and Pull factors on the intention to switch to the block chain system and the moderating effect through the switching cost which is a Mooring factor, were verified. The hypothesis was verified using a structural equation model using a sample of 320 response data by conducting a questionnaire survey on small and medium-sized enterprises located in Korea. As a result of the study, social influence, which is a push factor, and management's will to innovate, which is a Pull factor, had a significant effect on switching intention. And the moderating effect between the groups with high and low switching cost recognition was confirmed. This study is significant in that it presents the concept and research direction of SCBM (supply chain & blockchain management) that can enhance the competitiveness of a company through the implementation of a blockchain-based supply chain management information system.

• Korean Chemical Engineering Research
• /
• v.61 no.1
• /
• pp.80-88
• /
• 2023

Ensuring safety in the designing of manufacturing and handling facilities for low-density polyethylene (LDPE) is difficult because there are no standards for the dust explosion characteristics of LDPE. In this study, a dust explosion test was performed on two dust samples collected from a bag filter (LDPE 1) during the LDPE manufacturing process and sedimentary dust (LDPE 2) leaked outside a facility such as a silo, and the LDPE 2 explosion test results were summarized. Particle size analysis showed that the volume-based particle diameter (median) was 95.04 ㎛ and the number density was 0-1 ㎛. The maximum explosion pressure (P_max) was 6.6 bar, and the maximum rate of explosion pressure rise was 366 [bar/s] at 1500 g/m³. Accordingly, the dust explosion index (K_st) was 99.4 bar·m/s, which was confirmed as ST-1 grade. Moreover, the minimum ignition energy and minimum ignition temperature was 10 mJ and 450 ℃, respectively. Currently, manufacturing and handling design is based on the characteristic values of high-density polyethylene (HDPE). However, as the test results show that LDPE 2 dust has a higher risk than HDPE (particle diameter 61.6 ㎛), caution is required when using the HDPE design criteria in the LDPE manufacturing process.

• Composites Research
• /
• v.19 no.1
• /
• pp.9-14
• /
• 2006

Experimental investigation on heat transfer ratio was firstly performed with three types of sandwich panels such as the Carbon/Epoxy Skin-Aluminum Honeycomb and Balsa Core Sandwich Panel of 37mm thickness, the Carbon/Epoxy Aluminum Skin-Honeycomb Core Sandwich Panel of 57mm thickness (including insulator) and the Carbon/Epoxy Skin-Aluminum Honeycomb Core Sandwich Panel of 37mm thickness based on the KS F 2278:2003(Insulation test method of windows). In additional to this investigation, experimental tests were also done for evaluation of heat transportation ratio with the Aluminum Skin- Aluminium Honeycomb Sandwich Panels of 27mm and 35mm thickness, and Aluminum Skin-Foaming Aluminum Sandwich Panel of 27mm thickness by the KS F2277:2002 (Insulation measuring method of construction component-Calibration heat box method or protective heat box method). In this study, it was found that the larger net heat transfer cross sectional area between the skin and the sandwich core is given, the higher heat transportation ratio occurs. It was also found that the hybrid type insulation had better insulation characteristics compared to the non-hybrid type insulation.