• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.164-176
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• 2012

In the present study, rapeseed flour (RSF), which is a by-product from the production of edible oil and biodiesel extracted from rapeseed, was used to develop alternative adhesives for the production of plywood panels. To examine the effects of the enzyme on the adhesive properties and formaldehyde emission of the RSF-based adhesive resins, three enzymes, such as cellulase (CEL), pectinase (PEC) and protease (ALC), were used either separately or together. As a crosslinking agent, PF prepolymers, which were prepared with 1.5, 1.8 and 2.1 mole formaldehyde and 1 mol phenol (1.8-, 2.1- and 2.4-PF), were added into the RSF hydrolyzates. The adhesive resins formulated with CEL- or CEL-PEC-RSF hydrolyzates and 1.8-F/P PF prepolymers exhibited excellent adhesive strengths and formaldehyde emission. The tensile shear strength and formaldehyde emission of the plywood panels bonded with the formulate resins were satisfied with the minimum requirement of the KS standard for ordinary plywood panels (0.6 N/$mm^2$). In addition, formaldehyde emissions of the plywood panels approached to that of E0 specified in the KS standard (0.5 mg/${\ell}$), and even had much better than those of commercial UF glue mixes. Overall, the use of RSF-based adhesive resins for the production of plywood panels might provide durable adhesive properties and an environmentally friendly substitute for petroleum-based adhesive resins. However, further researches - the increase of solid content of RSF-based adhesives for reducing press time and the microscopic observation of plywood specimen for identifying the relationship between tensile shear strength and the penetration of adhesives into wood structure - are required to commercialize the RSF-based adhesives.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.605-610
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• 2011

Phase holdup characteristics of relatively large and small bubbles were investigated in a three-phase(gasliquid-solid) fluidized bed of which diameter was 0.105 m(ID) and 2.5 m in height, respectively. Effects of gas(0.01~0.07 m/s) and liquid velocities(0.01~0.07 m/s) and particle size($0.5{\sim}3.0{\times}10^{-3}m$) on the holdups of relatively large and small bubbles were determined. The holdups of two kinds of bubbles in three phase fluidized beds were estimated by means of static pressure drop method with the knowledge of pressure drops corresponding to each kind of bubble, respectively, which were obtained by dynamic gas disengagement method. Dried and filtered air which was regulated by gas regulator, tap water and glass bead of which density was $2500kg/m^3$ were served as a gas, a liquid and a fluidized solid phase, respectively. The two kinds of bubbles in three-phase fluidized beds, relatively large and small bubbles, were effectively detected and distinguished by measuring the pressure drop variation after stopping the gas and liquid flow into the column as a step function: The increase slope of pressure drop with a variation of elapsed time was quite different from each other. It was found that the holdup of relatively large bubbles increased with increasing gas velocity but decreased with liquid velocity. However, the holdup showed a local minimum with a variation of size of fluidized solid particles. The holdup of relatively small bubbles increased with an increase in the gas velocity or solid particle size, while it decreased slightly with an increase in the liquid velocity. The holdups of two kinds of bubbles were well correlated in terms of operating variables within this experimental conditions, respectively.

• Journal of Wetlands Research
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• v.22 no.1
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• pp.24-30
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• 2020

To assess the wetland systems' capability to reduce fine dust, we used an artificial wetland module of small-sized greenhouse (70cm W × 70cm L × 60cm H) which creates a closed system. Experiment was performed twice using four species in each experiment. Non-plantation, one species, or two species condition was created in each mesocosm. We measured air quality, primarily PM2.5 and PM10 at the initial open mesocosms and 1hr later since mesocosms were closed. The dry weight of vegetation was measured at the 2nd experiment. The decreased amount of PM2.5 and PM10 was 13.7±1.3 and 13.2±1.3 ㎍·m^-3hr^-1 in wetland condition and 15.0±1.4 and 13.8±1.5 ㎍·m^-3hr^-1 in dryland condition, respectively. In 2^nd experiment, the decreased amount of PM 2.5 and PM 10 in wetland condition was 13.7±1.3 and 9.2±1.5 ㎍·m^-3hr^-1, 15.0±1.4 and 8.8±1.4 ㎍·m^-3hr^-1 in dryland condition, respectively. Wetland showed higher removal effect due to its high productivity leading to more effective absorption of particulate matter. Furthermore, the aquatic characteristics of wetland system and high humidity helped purifying the air quality. This can be seen as another value of wetlands, which can be presented as one of the solutions to the problem of fine dust.

• Journal of Animal Environmental Science
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• v.6 no.3
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• pp.191-199
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• 2000

This study was initiated to investigate the influence of biophysical condition on the composting characteristics, and conducted to develop technology for using recycled compost as a bulking agent cost to reduce operating cost. To methods of aeration, continuous aeration (CA: run No. I) and intermittent aeration (IA: run No. 2) were performed with three 12.3 liter laboratory scale vessels for ten days. Manure and rice hulls were mixed for thirst trial (I), rice hulls and recycled compost after first trial were mixed for second trial (II), dairy manure and only recycled compost after second trial were mixed for third trial (III). During the composting process, temperatures of the compost mass and ammonia emissions were measured. The quality and maturity of compost were ascertained by examining the characteristics and composition of the compost. Also, loss of mass was determined by measuring the mass of materials in the vessels before and after composting. The results in this study are as follows: 1. The periods of optimum temperature ($>55^{\circ}C$) to kill pathogens were maintained from 38 to 78 hours for CA and from 60 to 98 hours for IA. 2. The more recycled compost mixed, the more ammonia emitted. The maximum ammonia emissions were 287 ppm at CA and 420 ppm at IA. 3. Biofiltration system was required for the compo sting system using only recycled compost as an amendment, because the ammonia emissions was produced above 100 ppm at the end of composting process. 4. The quality and maturity of compost: - Fresh compost, were required drying, because moisture contents of the compost were approximately 70% in all tests. - The pH values were observed to rise smoothly, from 7.9 to 8.3 at CA and from 8.4 to 8.6 at IA. The CfN ratios of the fresh compost were ranged form 21.05 to 16.42 for CA and from 22.81 to 14.75 for IA. The final C/N ratios for test II and III were below 20.were below 20.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.484-491
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• 2005

Quantitative microbial risk assessment (QMRA) analyzes potential hazard of microorganisms on public health and offers structured approach to assess risks associated with microorganisms in foods. This paper addresses specific risk management questions associated with Staphylococcus aureus in kimbab and improvement and dissemination of QMRA methodology, QMRA model was developed by constructing four nodes from retail to table pathway. Predictive microbial growth model and survey data were combined with probabilistic modeling to simulate levels of S. aureus in kimbab at time of consumption, Due to lack of dose-response models, final level of S. aureus in kimbeb was used as proxy for potential hazard level, based on which possibility of contamination over this level and consumption level of S. aureus through kimbab were estimated as 30.7% and 3.67 log cfu/g, respectively. Regression sensitivity results showed time-temperature during storage at selling was the most significant factor. These results suggested temperature control under $10^{\circ}C$ was critical control point for kimbab production to prevent growth of S. aureus and showed QMRA was useful for evaluation of factors influencing potential risk and could be applied directly to risk management.

• Food Science and Preservation
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• v.17 no.4
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• pp.471-477
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• 2010

We explored the effects of curing and smoking conditions on the shelf life of Dombaeki (shark meat). Dombaeki cured for 12 h in an aqueous solution containing (per 100 ml) salt 5.6 g, sugar 14 g, and garlic powder 0.6 g, showed the best sensory quality among various samples cured for 0, 3, 6, 9, 12 or 24 hours. The optimum conditions for preparation of smoked Dombaeki (SD) were drying at $60^{\circ}C$ for 30 min, followed by cooking at $80^{\circ}C$ for 30 min and smoking at $65^{\circ}C$ for 40 min, as judged by sensory evaluation of taste, color, flavor, texture, and overall acceptability. The volatile basic nitrogen content of air- or vacuum-packed unsmoked Dombaeki (NSD) was above 20 mg% after storage for either 12 days or 5 weeks. However, the nitrogen contents of air- and vacuum-packed SD were less than 20 mg% after either 21 days or 10 weeks of storage at $10^{\circ}C$. The DPPH free radical-scavenging ability of SD (73.9%) was significantly higher than that of unsmoked meat (4.54%). The total polyphenol content of SD (745.6 g/g) was about 4-fold greater than that of unsmoked meat (179.5 g/g).The viable bacterial count of air- or vacuum-packed unsmoked meat was over $10^6\;CFU/g$ after storage for either 12 days or 5 weeks. However, air- or vacuum-packed SD had counts under $10^4\;CFU/g$ at all storage times tested. Changes in coliform bacterial levels paralleled those of total viable cells. The sensory quality (taste, color, flavor, appearance, texture, and overall acceptability) of SD was significantly better than that of NSD.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.267-274
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• 2017

This study discusses the applicability of environmental friendly EVA based butyl rubber self-adhesive waterproof sheet designed to prevent corrosion of large scale pipes used in the water treatment facilities during th water treatment process. The experiments conducted tested the waterproofing sheet's adhesion strength on the steel surface of the pipes and checked for whether the material has the proper response properties against the various environmental conditions. In addition, it the sheet adhered to the steel pipe was to see if the adhesion hold against the water pressure due to the ingress of inflow water. Finally, the waterproofing sheet's adhesion strength was tested on a rusted steel surface to confirm whether the material has the necessary properties to secure stable adhesion strength and prevent corrosion of steel pipes at the same time during the process of installation or maintenance. As a result, the self-adhesive waterproof sheets showed that all attachments in the untreated, long term pressuring, immersion in chemical substance (hydrochloric acid, hypochlorous acid, sodium hydroxide), low temperature ($-20^{\circ}C$) conditions showed a adhesion performance of higher than 1.5N/mm, which is the performance standard of KS F 4934. Also, in the testing to check for the adhesion property against inverse water pressure, it was observed that the adhesion failure did not occur even up to $3.0N/mm^2$ pressure. Also, in the process of assessing the adhesion performance on rusted steel surface, specimens after 12 hours of corrosion treatment was shown to have 2.1N/mm, and specimens after 168 hours of corrosion treatment was shown to have 2.0N/mm adhesion strength performance.

• Korean Journal of Food Science and Technology
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• v.49 no.6
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• pp.575-583
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• 2017

Germination is a well-known economical technique that has been utilized to enhance the nutritional value of brown rice. Owing to its higher nutritive quality, germinated brown rice has received significant attention in the past decade. In this study, the physicochemical and cooking properties of specialty brown rice (SBR) were analyzed before and after germination. Germination enhanced cooking properties such as water absorption, expanded volume, and increased solid solubility of cooked SBR. The SBR texture measured using tensipresser, was significantly improved by germination. The hardness of cooked SBR was decreased by germination, but stickiness was increased. Pasting analysis of the SBR flours revealed a decrease in all viscosity values (peak viscosity, breakdown, setback, and final viscosity) after germination. However, the gelatinization temperature remains unchanged upon germination. Additionally, amylose content and amylopectin chain length distribution of SBR starch were slightly changed by germination. These results indicate that germination leads to a substantial improvement in the cooking properties and texture of SBR.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.4
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• pp.65-69
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• 2009

Purpose: Recently incidence of VDT syndrome has gradually increased as extensive use of computers. VDT syndrome reported by VDT workers include musculoskeletal disorder, neuropsychiatric disoders and eye symptoms such as eye strain, tired eyes, irritation and blurred vision. The environmental factors of VDT syndrome include electromagnetic waves, size, brightness and lighting of computer screen, height of a monitor and a worktable, working hours, kind of task, distance between screen and workers, indoor humidity and temperature, indoor air contamination and ventilation. In this study, we investigated the environmental factors related to body symptoms and health effects included in VDT syndrome. Methods: Study subjects were total 120 persons (54 male, 66 female) with age from 19 to 28. We surveyed the body symptoms and physical discomfort when doing an activity in a short distance such as reading book or paper, computer work. The questionnaire included main body symptoms, self-consciousness symptoms of eye, satisfaction of working environment, pain of the wrist when using keyboard and mouse. Results: Most of people (70%) felt physical pain from long time work of computer, paper, electrical apparatus. They mainly complained pain of neck and low back (57.1%), eye (45.2%) and head (31%). With the environmental factors, 78.3% of the subjects complaint pain of eye from inappropriate illumination. Most of the symptoms included 'eye fatigue'(38.3%), 'dryness of eye'(31.9%) and 'blurred vision'(23.7%). Subjects in this study complained discomfort of their chairs and most of them experienced pain in the wrist when using keyboard or mouse. Conclusions: When people use electrical apparatus or work with paper, people would get their eye fatigue and feeling of physical fatigue because of not harmonizing various environmental factors such as light, space, posture, worktable with theirselves. Therefore, workers should develop preventive method such as self-control of adequate break time to avoid fatigue while VDT work. Work environment should be changed to ergonomic design for optimal visual environment to prevent musculoskeletal disorder through constant research.

• Journal of Sasang Constitutional Medicine
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• v.12 no.1
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• pp.120-135
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• 2000

Objective ; The purpose of this study is to find out the constitutional symptomatic pattern of Soyangin and Taeumin through investigation of difference between two groups in stroke. Method ; 70 inpatients(Soyangin 31, Taeumin 39) in stroke, admitted into Kyung-Hee Oriental Hospital from 1. July. 1999 to 20. Sept. 1999, were investigated through questionnare which consists of 16 parts 155 questions, and the problems which have significant difference between Soyangin and Taeumin group were analyzed statistically. Result 1. The analysis of general characteristic difference between Soyangin and Taeumin group (1) The number of Soyangin patients is 31, Taeumin 39 and the number of Male patients 43, Female 27. (2) The mean weight of Taeumin group is heavier than that of Soyangin group and the degree of obesity of Taeumin group higher. (3) The number of patients who have smoking history is more at Soyangin group. (4) In neurological problem, dizziness is more complained of in Soyangin group. 2. The analysis about the result of Questionnare (1) In problems related with 'Sleeping', the time of going to bed and getting up and the duration of sleeping are more irregular in Taeumin group. (2) In problems related with 'Defecation', the shape of stool is more variable in Taeumin group. (3) In problems related with 'Urination', Soyangin group have more complaint. (4) In problems related with 'The condition of digestion', Taeumin group have a good appetite and more compalint in lower abdominal region, but on the contrary Soyangin group lose appetite and have more complaint in upper abdominal region. (5) In problems related with 'Head and Face', Soyangin group have more complaint. (6) In problems related with 'Eye, Ear and Nose', Soyangin group have more complaint at eye and ear. (7) In promlems related with 'Chest region', Soyangin group easily feel choked up and Taeumin group heart throbs. (8) In problems related with 'Skin', Taeumin group easily feel change of color tone at skin and Soyangin group dry.