• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.43-53
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• 2008

Because the torque control method, which is also caled the clamping method in domestic construction sites, is affected by a variation of the torque coefficient, quality control of the torque coefficient is essential. This study was focused to evaluate the effects of several environmental factors and errors when installing bolts while tightening high-strength bolts. Conditioning environmental parameters include wet, rusty and exposure-to-air-only conditions. In addition, because of errors in workability such as instalation of two washers, upset washers are selected. During the tests, torque, torque coefficient, tension and angle of nut rotation were obtained using a bolt testing machine. Test specimens of four types of bolts (High-Strength Hexagon bolt on KS B 1010, Torque Shear Bolt on KS B 2819, High-Strength Hexagon bolt coated with zinc, and ASTM 490 bolt) were recomended. Based on test results, the tightening characteristics subjected to environmental parameters were investigated and compared with the results in normal condition.

• The Korean Journal of Food And Nutrition
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• v.16 no.4
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• pp.417-422
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• 2003

Addition of whole soy flour(WSF) to wheat flour(WF) was studies for its effects on dough and noodle characteristics. The WF used was medium grade of strength and WSF was a fine flour of 350 mesh. The addition ratio of WSF to. n was up to 20%. The dough properties and textural properties of wet and cooked noodles were measured with using Farinograph, Amylograph and Rheometer. Farinogram data showed the minimum dough development time and stability at 6% addition of WSF. Amylograph data of initial pasting temperature and time were increased while the maximum and final viscosity and setback were decreased as the WSF added more to W The initial pasting temperature of 2.0∼6.0% WSF added flour were comparable to 100% WF eventhough viscosity was almost half of WF. The water absorption capacity was increased from 81.6% to 92.3% at 6.0% WSF and then decreased as the addition ratio of WSF increased. The extensibility of dough showed a maximal value at 8.0% WSF addition. Strengthness and hardness of wet and cooked noodle were increased to the heighest measurement as the WSF added up to 6.0% followed by a steady decrease thereafter. It was also found that WSF addition resulted an increase in adhesiveness of wet noodle and decrease in hardness and strengthness of cooked noodle.

• Journal of the Korean Wood Science and Technology
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• v.37 no.1
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• pp.56-64
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• 2009

The purpose of this study was to investigate and develop an eco-friendly wood adhesive based on vegetable oil (especially soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The soybean oil (SBO) was reacted with $O_3$ at the rate of 7.13 g/h for different times, 15 minutes, 30 minutes, 60 minutes, and 120 minutes. The investigation of the modified chemical structure of the ozonized SBOs were conducted using FT-IR, $^1H$-NMR, MALDI-TOF MS, and GC/MS. As ozonification time increased, the peak of the unsaturated double bonds was disappeared and aldehyde or carboxyl peak appeared because ozonification broke the oil into small molecules. The plywoods were made at $110^{\circ}C$ with 30 seconds/mm hot-press time using the different ozonized SBO/pMDI adhesives and were tested for the dry, wet, cyclic boil test according to the Korea Industrial Standard F3101 Ordinary plywood. The bond strengths gradually increased with increasing ozonification time. The weight ratio 1:1 (ozonized SBO/pMDI), all strengths in 15, 30 and 60 minuets, exceeded constantly the dry, wet, cyclic boiling standard requirement. The range of ozonification time and weight ratio can fulfil1 the requirment of the wet test standard were 30~60 minutes and more than 0.5 pMDI. From the comprehensive view on the results of above experiments, it could be confirmed through experiments that ozonized SBO/pMDI has characteristics of effective reactivity and wet stability showed as an excellent candidate of wood adhesive applications.

• Culinary science and hospitality research
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• v.15 no.1
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• pp.128-136
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• 2009

In this study, Korean wheat wet noodles were prepared with 1, 3, 5, and 7% pomegranate cortex powder(PGCP). The samples and a control were compared in terms of quality characteristics, including cooking properties, colors, textural characteristics, and sensory evaluation in order to determine the optimal ratio of PGCP in the formulation. With regard to the cooking properties, weight, volume, and water absorption decreased with PGCP content increased. As for colors, the PGCP content L, a, b value increased. For the textural characteristics, springiness and cohesiveness were not significantly different among the samples. The PGCP samples had significantly higher hardness, chewiness, brittleness, and gumminess than the control group. However, strength showed the reverse effect. In the sensory evaluation, the control group had significantly higher scores in colors, texture, and chewiness as compared to the PGCP samples. Overall acceptability decreased with PGCP content increased while bitterness, astringency, and off-flavor increased. Furthermore, saltiness and gumminess were not significantly different among the samples. In conclusion, the results show that 1% of PGCP was proved very useful as a substitute for Korean wheat flour in the production of wet noodles, providing good nutritional and functional properties.

• Clean Technology
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• v.25 no.2
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• pp.114-122
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• 2019

The synthesis of bio polyol from renewable resources has attracted attention in recent years. In particular, it is important to take advantage of bio polyols in the synthesis of polymers. In this study, a series of dimethylformamide (DMF) based polyurethanes were synthesized using polycarbonate polyol/bio polyol (PO3G: polytrimethylene ether glycol prepared from 1, 3-propanediol produced by fermentation from corn sugar), methylene diphenyl diisocyanate (MDI) and 1,4-butandiol (BD). The properties of prepared polyurethane films and the cell structure of wet type artificial leather were investigated. As the bio polyol content increased, the tensile strength of polyurethane films decreased, however, the elongation at break increased significantly. As a result of thermal characteristics analysis, the glass transition temperature of polyurethanes increased when increasing the content of polycarbonate polyol. As a result of comparing the cell characteristics of wet type artificial leathers prepared in this study, it was found that the number and uniformity of cells formed in the artificial leather samples increased when increasing the content of polycarbonate polyol in polycarbonate polyol/bio polyol. From these results, it was found that DMF-based polyurethane containing an appropriate amount of bio polyol could be used for wet type artificial leather. The bio textile analysis system according to ASTM standard was used to measure the bio carbon content of polyurethane. The content of bio carbon increased proportionally with the increase of bio polyol content used in polyurethane synthesis.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.167-176
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• 2021

When producing recycled asphalt mix, it is important that the old binder of reclaimed asphalt pavement(RAP) should be well melted during blending in the mixer. The recycled asphalt mix is produced by instant mixing(IM) of all materials(RAP, virgin asphalt and new aggregates) all together in the mixer. However, in the same recycled mix, the binder around RAP aggregate was found to show higher oxidation level than the binder coated around the virgin aggregate because the old binder of RAP was not rejuvenated properly while instant mixing. The partially-rejuvenated RAP binder is assumed to be a high stiffness point in IM recycled mix. In this study, the stage mixing(SM) method was introduced; blending RAP and virgin asphalt for the first stage, and then mixing all together with hot new aggregates for the second stage. To compare the effect of the two mixing methods on moisture resistance of recycled mixes, a statistical t-test was performed between SM and IM using indirect tensile strength(ITS) and tensile strength ratio(TSR). Three conditioning methods were used; a 16-h freezing and then 24-h submerging, 48-h submerging, and 72-h submerging in 60℃ water. It was found that the TSR(=ITS_wet/ITS_dry) values of the mixes prepared by SM was clearly higher than the IM mixes, and coefficients of variation of SM mixes were lower than the IM mixes. It was also observed that the ITS_WET of SM was significantly different from the IM at α=0.05 level by statistical t-test. The ITS_WET of SM mix was reduced less than the IM mix in severer conditioned mixes. Therefore, it was concluded that the stage mixing method was an important blending technique for producing better-quality of recycled asphalt mixes, which would show higher moisture resistance than the recycled mixes produced by conventional instant mixing.

• Food Science and Preservation
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• v.6 no.2
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• pp.167-172
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• 1999

The noodle making characteristics were investigated for both eleven varities of Korean wheat, such as Chokwangmil, Geurumil, Eunpamil, Tnpdongmil, Woorimil, Oigeurmil, Alchanmil, Cobunmil, Geumgangmil, Seodunmil and Suwon 265, and two varieties of imported wheat, DNS(Dark Northern Spring Wheat) and ASW(Australian Standard White). After cooking of dry-noodle, the elasticities were 0.59-0.79 in the native wheat and 0.55-0.57 in the imported wheat. Among the varieties showing the highest value in the various texture properties of cooked dry-noodle, Alchanmil was highest in gumminess, Geungangmil in cohesiveness, Olgeurumil in adhesiveness, Geurumil in fimmess, Chokwang in chewiness, Tapdongmil in tensile strength Gobunmil in breaking strength. After cooking the wet-noodle, Tapdongmil in elasticity, Geurumil in adhesiveness, Geumgangmil in gumminess, cohesiveness, firmness and chewiness, and Suwon 265 in tensile strength showed the highest values in the respective textural properties. From the sensory evaluation of the cooked dry-noodle, the significant differences (p<0.05) among wheat varieties were observed in color, texture and overall quality. As a result, ASW was excellent in our all qualities of cooked dry-noodle followed by Tapdongmil, Alchanmil and Geumgangmil. The cooked wet-noodle also showed the high sensory scores (p<0.01) were showing the best in Tapdongmil, followed by Eunpamil, Geumgangmil and Woorimil.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.385-388
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• 2008

Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. Also, alkaline water occurred from treatment process of the waste concrete is becoming the cause of environmental problem. Accordingly, this study is to develop on the high quality recycled fine aggregate produced by low speed wet abraser using sulphuric. We investigated the properties of compressive strength of the mortar which was manufactured using recycled fine aggregate containing calcined gypsum produced by earlier mentioned process. Test results indicate that concrete using recycled fine aggregate containing calcined gypsum is higher compressive strength than concrete using other sands.

• Journal of the Korean GEO-environmental Society
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• v.9 no.1
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• pp.47-54
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• 2008

In this study, the effect of water content condition was investigated on the Mohr-Coulomb shear strength parameters which are commonly used as the input data in the soil slope analysis. For the purpose, a series of direct shear test was conducted in different water content conditions on the two types of weathered soils and a dam core material, obtained from the domestic slope construction sites and the dam construction site, respectively. The comparisons between the values of the Mohr-Coulomb ${\phi}_{peak}$ and $c_{peak}$, estimated from the relationships between the normal stress and the peak shear stress for the samples in the four different water content conditions (i.e., dry side, optimum, wet side, and saturated), showed that overall, the values of $c_{peak}$ decreased gradually while those of ${\phi}_{peak}$ did not vary much with increasing the water content. A rough estimate for the varying ratio of the values of ${\phi}_{peak}$ and $c_{peak}$ indicated that the values of $c_{peak}$ decreased by every 25% of the $c_{peak}$ values in dry side, while those of ${\phi}_{peak}$ were constant, as the water content condition changed from dry, optimum, and wet to saturated, respectively.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.93-99
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• 2000

Treatment of shaving scrap, a chrome containing solid scrap generated by leather manufacturing process, has been so far depended on mainly incineration, soil landfill and ocean dumping, which give bad impact on environment and cause pollution. Shaving scrap generates from the mechanical work for controlling the final thickness of leather and its main components are collagen protein and pan of chromium compound. For the purpose of reusing this leather waste as resources, researches in connection with collagen fiber recovery, gelable protein recovery and liquid fertilizer is being speedily progressed. In the experiment, shaving scrap went through wet pulverizing treatment by physical and chemical methods. Then, making the leather sheet evenly, it is mixed with natural latex and every kind of binding materials in the container, and the mixtures were passed through experimental hydraulic press machine and applied to Fourdrinier machine respectively. Lastly, a test for fading out physical strength and properties of multiple-purpose of leather-like material was performed on a continuous leather sheet prepared by the experiment. In result, the physical strength and properties of leather-like material showed noticeable differences according to mixing ratio of binding materials, beating methods and the Ends of binding materials selected, and generally tear strength was the weakest property among others. Also, by the pilot scale experiment in sequence, it was possible to manufacture recycled goods made of soft and hard types of leather-like material with various performances.