• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.10-21
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• 2006

Recycled polypropylene (RPP) - Wood Saw Dust (WSD) composites with and without acetylation of filler were produced at different filler loading (15%, 25%, 35% and 45% w/w) and filler size (300, 212 and $100{\mu}m$). The RPP-WSD was compounded using a Haake Rheodrive 500 twin screw compounder at $190^{\circ}C$ at 8 MPa for 30 minutes. The mechanical properties and water absorption properties of modified and unmodified WSD-PP composites were investigated. Acetylation of WSD improved the mechanical and water absorption characteristic of composites. The decrease of filler size (300 to $100{\mu}m$) of the unmodified and acetylated WSD showed increase of tensile strength and impact properties. The composites exhibited higher tensile modulus properties as the filler loading increased (15% to 45%). However tensile strength, elongation at break and impact strength showed the opposite phenomenon. Water absorption increased as the mesh number and filler loading increased. With acetylation, lower moisture absorption was observed as compared to unmodified WSD. The failure mechanism from impact fracture of the filler-matrix interface with and without acetylation was analyzed using Scanning Electron Microscope (SEM).

• The Korean Journal of Ecology
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• v.6 no.4
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• pp.243-249
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• 1983

Absorption pattern of potassium, calcium, phosphate and nitrate ions, and the pH change during ion-absorption at pH 3.0-11.0 by Oryza sativa L. were studied to investigate indirectly the evidence of H^+-efflux by ATPase. The rice seedlings which were grown either in $L^{\circ} -dark or in L^+-sunlight$, were used both in each ion-absorption to compare with one another. The uptake rate of these ions appeared to favor more in $L^+than in L^{\circ}$, over all range in pH, nearly with the same pattern. The absorption of potassium resulted in bell shape and that of calcium increased linearly to the alkali range. The shape of phosphate-absorption showed nearly the t-distribution curve with high value in acid range and the uptake of nitrate resulted in the dual peaks, but higher in acid range. The pH of the external solution changed from the range of 3.5-11.0 to 3.5-7.0 after lhr-absorptioin, and further acidified after 3hr-absorption. It is suggested that the pH change of the external solution be affected by $ H^+-efflux$ which may be caused by the ATP-hydrolysis.

• International Journal of Human Ecology
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• v.4 no.1
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• pp.35-44
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• 2003

This study investigated the effects of dietary phyate reduction on the apparent absorption and biochemical parameters of iron status in young Korean women. Fourteen healthy, young women consumed low and high phytate diets for ten days of each experimental period. Duplicate diet samples, a fasting blood sample on day 9, and complete fecal samples for five consecutive days starting from day 5 of each diet period were collected. The iron content of diet and fecal samples were analyzed to calculate apparent absorption. Serum samples were analyzed for iron, ferritin, transferrin receptor and TIBC; transferrin saturation was also calculated. The apparent absorption of iron tended to increase in the low phytate period (32.51%) compared to the high phytate period (17.91%), but the difference was not significant (p=0.06). Serum ferritin decreased and serum transferrin receptor increased significantly during the low phytate diet although the mean values were within the normal range. Serum iron and transferrin saturation did not change significantly. In conclusion, the results indicated that reducing dietary phytate for ten days negatively affected iron nutritional parameters, but it moderately and positively affected apparent iron absorption in young Korean women. Further research on the long-term effects of a low phytate diet with an adequate iron content for vows Korean women is necessary.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1347-1354
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• 1999

Recently, the markets of the air conditioner are enlarging. The market size will reach 2.0 billion won in 2000. Electric heat pumps have been utilized as main residential air conditioners. especially in Korea. They cause a surge up electric power demand during summer. Moreover, the use of HCFCs and HFCs causes serious problem to the global environment such as global warming and ozone layer destruction. Absorption chiller and heater could solve such problems. It was built and tested for analyzing the performance of the generator for absorption chiller and heater. Experiment was done with a high temperature generator, a low temperature generator, heat exchangers, a condenser and a solution tank. It was tested that the double effect series flow cycle with two kinds of solution cycle. Solution cycle B showed better than solution cycle A. Two kinds of heat exchanger were used, where one's heat transfer area is bigger than the other. Bigger one increased a little performance of absorption chiller and heater. But it was not economical. From this study, we got that the coefficient of performance(COP) is 0.82 and the capacity is 7.24 kW for an absorption chiller and heater.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.332-337
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• 2004

The use of gas absorption refrigeration machine has considerably increased because of the shortage of the electric power in the summer and the regulation of freon refrigerant. Gas absorption refrigeration machine consists of a condenser, a heat exchanger. supplying pipes, a radiator etc, This system is likely to be corroded by acid. dissolved oxygen and gases, Cavitation erosion-corrosion by flow velocity of cooling water may happen in absorption refrigeration machine. In these cases. erosion and corrosion occur simultaneously. Then, it makes a serious damage with synergy effect. Therefore, this paper was studied on the cavitation damage of cupronickel(70/30) tube for gas absorption refrigeration machine, In the $30^{\circ}C$ tap water, linear polarization test and anodic polarization test were carried out for copper(C1220T-OL) and cupronickel(70/30) tube. Also, cavitation erosion-corrosion behavior of cupronickel (70/30) tube was considered, The main results are as following: (1) In the linear test, the corrosion current density of cupronickel(70/30) is higher than that of copper. (2) The erosion-corrosion rate of cupronickel(70/30) displayed later tendency than that of copper by vibratory cavitation in cooling water. (3) In cooling water, the progress mechanism of erosion-corrosion rate of copper and cupronickel(70/30) follows a pattern of incubation, acceleration, attenuation and a steady state period.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.782-789
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• 2010

It is important to satisfy the requirements and standards for the protections of passengers in a car accident. There are lots of studies on the crushing energy absorption of a structure member in automobiles. In this paper, we have studied to investigate collapse characteristics and moisture absorption movements of CFRP( carbon fiber reinforced plastics) structure members when CFRP laminates are under the hygrothermal environment. In particular, the absorbed energy, mean collapse load and deformation mode were analyzed for CFRP members which absorbed most of the collision energy. Also, variation of stacking angle is important to increase the energy absorption capability. The purpose of this study is to evaluate the strength reduction and moisture absorption behavior of CFRP hat shaped member. Therefore we have made a impact collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed. As a result, the effect of moisture absorption and impact loads of approximately 50% reduction in strength are shown.

• Steel and Composite Structures
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• v.28 no.2
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• pp.179-194
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• 2018

Reliable and accurate method of computationally aided design processes of advanced thin walled structures in automotive industries are much essential for the efficient usage of smart materials, that possess higher energy absorption in dynamic compression loading. In this paper, most versatile components i.e., thin walled crash tubes with different geometrical profiles are introduced in view of mitigating the impact of varying cross section in crash behavior and energy absorption characteristics. Apart from the geometrical parameters such as length, diameter and thickness, the non-dimensionalized parameters of average forces which control the plastic bending moment for varying thickness has explored in view of quantifying its impact on the crashworthiness of the structure. The explicit finite element code ABAQUS is utilized to conduct the numerical studies to examine the effect of parametric modifications in crash behavior and energy absorption. Also the simulation results are experimentally validated. It is evident that the circular cross-sectional tubes are preferable as high collision impact shock absorbers due to their ability in withstanding axial and oblique impact loads effectively. Furthermore, the specific energy absorption (SEA), crash force efficiency (CFE), plastic bending moment, peak force responses and its impact for optimally tailoring a design to cater the crashworthiness requirements are investigated. The primary outcome of the study is to provide sufficient information on circular tubes for the use of energy absorbers where impact oblique loading is expected.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.4 s.121
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• pp.342-349
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• 2007

Following the 2002 World-Cup held in Korea, studies have been actively conducted on plans to utilize all-weather stadiums of fine figures, where large-scale spaces are available for various utilizations. In Japan, dome-type stadiums have been built and are utilizing across the whole nation not only for sports events but also variety of other large-scale events. PTFE(poly tetra fluoro ethylene) is one of the membrane material mainly used for the outer ceiling surface of membrane structures. However, there has not been enough research on the acoustical properties of PTFE membrane material which has been widely used in the multi-purpose stadiums. In this study, air permeability values and sound absorption coefficient of PTFE membrane materials were measured and evaluated in the gymnasium. From the results of measurements of sound absorption coefficient and air permeability of inner membrane materials, it was found that the sound absorption coefficient was good in the air permeability range of $5{\sim}15\;cc/cm^2/s$. Also the relation ship between air permeability and sound absorption coefficient was very high and the sound absorption coefficient was the highest in the range of $6{\sim}9\;cc/cm^2/s$. Secondly, an analysis on the measurements sound absorption characteristics of inner membrane material reveals that the overall sound absorption coefficient was stabilized(higher than 0.5 throughout the whole frequency bands) when the air space behind the membrane material was deeper than 600 mm. When PTFE sound absorptive membrane material was installed in the ceiling of gymnasium, it was confirmed that sound absorptive membrane material can reduce reverberation and increase speech intelligibility in the gymnasium.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.78-88
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• 2015

Purpose: The objective of this study is to review researches regarding factors that potentially affect adolescent calcium (Ca) metabolism, and to suggest a potential modeling approach for optimizing gastrointestinal Ca absorption and peak bone mass. Background: Optimal gastrointestinal Ca absorption is a key to maximizing peak bone mass in adolescents. Urine Ca excretion in adolescents rises only after bone accretion is saturated, indicating that higher intestinal Ca absorption and bone retention is necessary to ensure maximum bone accretion. Hence, maximizing peak bone mass is possible by controlling the factors influencing gastrointestinal Ca absorption and bone accretion. However, a mechanism that explains the unique adolescent Ca metabolism has not yet been elucidated. Review: Dietary factors that enhance gastrointestinal Ca absorption may increase the available Ca pool usable for bone accretion, and a specific hormone may direct optimal Ca utilization to maximize peak bone mass. IGF-1 is an endocrine hormone whose levels peak during adolescence and increase fractional Ca absorption and bone Ca accretion. Prebiotics, generally obtained from dietary sources, have been reported to exert a beneficial effect on Ca absorption via microbiota activity. We selected and reviewed three candidates that could be used to propose a comprehensive Ca metabolic model for optimal Ca absorption and peak bone mass in adolescents. Modeling: Modeling has been used to investigate Ca metabolism and its regulators. Herein, we reviewed previous Ca modeling studies. Based on this review, we proposed a method for developing a comprehensive model that includes regulatory effectors of IGF-1 and prebiotics.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.3
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• pp.215-220
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• 2005

On entering new millenium, there has been an important switchover in the divergent View and its cases on commercial marketing. This study is to focus on the related influence factors of the optician's marketing. Aiming to improve the relationship of the manager and the manager and the clients, this study tried to find out the influences of the marketing. We defined quality of relation as three element, trust, satisfaction, absorption. We investigated how it influenced optician's characters, goods, service, price, physical convenience and communication to the quality of relation. Moreover, we investigated how it influenced optician characters like knowledge information, good impression, contact and relation marketing of dissatisfaction solution, also quality of relation could or not influence about repurchase intension and Big Mouth marketing. Optician's characters affect on affirmative effect to trust and absorption, but little affirmative effect to satisfaction. Since optician's characters are trust and absorption rather than satisfaction influence, they actively should improve customer-oriented variety of goods, service, physical convenience, communication. As price and communication structure of optician was formed so not modernized, we realized these have not influenced their trust, satisfaction, absorption to customer. Optician's characters influenced more affirmative effect to satisfaction than thrust and absorption. quality of relations mostly provided affirmative effect to the result of relation. The opticians should make efforts to influence on customer satisfied with goods and service, also to have trust and absorption for customer, should maintain good partnership with customer.