• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.249-257
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• 2010

In this paper, a three-dimensional hydrogen absorption model is developed to precisely study hydrogen absorption reaction and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The 3D model is first experimentally validated against the temperature evolution data available in the literature. In addition to model validation, the detailed simulation results shows that at the initial absorption stage, the vessel temperature and H/M ratio distributions are uniform throughout the entire vessel, indicating that the hydrogen absorption is so efficient during the early hydriding process and thus local cooling effect is not influential. On the other hand, nonuniform distributions are predicted at the latter absorption stage, which is mainly due to different degrees of cooling between the vessel wall and core regions. This numerical study provides the fundamental understanding of detailed heat and mass transfer phenomena during hydrogen absorption process and further indicates that efficient design of storage vessel and cooling system is critical to achieve fast hydrogen charging and high hydrogen storage efficiency.

• Journal of the Korean Wood Science and Technology
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• v.38 no.2
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• pp.101-107
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• 2010

Heat treatment was performed to improve sound absorption properties for four tree species; Tulip tree, Korean Paulownia, Red pine and Costata birch, at temperature of $175^{\circ}C$ and $200^{\circ}C$under vacuum condition. Sound absorption properties of two kinds of boards, which were in radial and tangential sections, were measured under a frequency range of 100 to 3200 Hz by the two microphone transfer function method. It was found that sound absorption properties were increased by heat treatment and the efficiency was higher at $200^{\circ}C$ than that at $175^{\circ}C$. Even Costata birch had a little effect on low temperature of $175^{\circ}C$, $200^{\circ}C$ heat treatment for sound absorption property, the efficiencies of sound absorption were 14, 19%, respectively. The efficiencies of sound absorption ranged 22 to 120% for heat-treated Tulip tree, Korean Paulownia.

• Fashion & Textile Research Journal
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• v.20 no.4
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• pp.457-463
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• 2018

This study examined the water absorption and drying properties of the thirteen types of the knitted fabrics for sports wear. These physical properties were analysed with relation to the constituent fiber cross-sectional shape and structure parameters of the knitted fabrics by regression analysis. Absorption and drying properties of the knitted fabric specimens were increased with increasing the porosity of the constituent yarns, which was attributed to the capillary channels in the yarns. The water absorption and drying properties were increased and decreased with increasing tightness factor and stitch density of the knitted fabric. The absorption property of the knitted fabric for perspiration absorption and fast dry sport-wear clothing was mostly influenced mostly by fiber cross-sectional shape and its characteristics, whereas, drying property was dependent on the structural parameters of the knitted fabric such as tightness factor and stitch density. Therefore, superior perspiration absorption and fast drying knitted fabric could be obtained in the fabric structure with optimum tightness factor and stitch density, and constituent yarn structure with non-circular fiber crosssection and high porosity. GATS method and MMT method are used to measure sweating fast drying properties and it is necessary to carry out studies using these measurement methods in order to compare with the results of this study.

• Journal of the Korean Wood Science and Technology
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• v.42 no.5
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• pp.615-623
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• 2014

Increases of public attention on healthy environment lead to the regulation of indoor air quality such as Clean Healthy House Construction Standard. This standard covers emission of total volatile organic compounds (TVOCs) (e.g., formaldehyde, benzene, and toluene), ventilation, and use of environmentally-friendly products or functional products. Moisture absorption and desorption abilities are a recommended functionality for improving indoor air quality. In this study, moisture absorption and desorption capacities of carbonized board from wood-based panels and other materials were determined by using UNT-HEAT-01 according to ISO 24358:2008. Pine had higher moisture absorption and desorption capacities ($49.0g/m^2$ and $35.3g/m^2$, respectively) than hinoki cypress, cement board, gypsum board, oriented strand board, and medium density fiberboard (MDF). The moisture absorption and desorption capacities differed considerably according to the wood species. After carbonization process at $400^{\circ}C$, the absorption and desorption ability of MDF increased to 38% and 60%, respectively. However, moisture absorption and desorption capacities decreased with increasing carbonization temperature, but they were still higher than original MDF. Therefore, it is suggested that carbonization below $600^{\circ}C$ can improve moisture absorption/desorption capacities.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.7
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• pp.486-491
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• 2008

The performance of a microturbine CHP system equipped with an absorption chiller was analyzed by modeling it. The microturbine with recuperator was simulated with the Brayton cycle model. The mass flow rate and available heat energy of the exhaust gas from the microturbine were simulated. These results were utilized as input values for the generator of the absorption chiller. The absorption chiller is a single-effect air cooled type with a solution heat exchanger. The heat input into the generator was proportional to the heat transfer rate and the UA values of the heat exchangers of the absorption chiller. Furthermore, the COP of the absorption chiller increased with respect to an increase of the heat input into the generator, under the sufficient evaporator capacity condition. When the capacity of the CHP system increased from 30 to 60 kW, the mass flow rate of the LiBr for the absorption chiller doubled, and the UA values for evaporator and condenser increased by factors of x3.9 and x3.4, respectively, under the same COP condition.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.29-37
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• 2015

Objective : The purpose of this study was to investigate the biomechanical properties of shock absorption strategy and postural stability during the drop landing for each types. Methods : The motions were captured with Vicon Motion Capture System, with the fourteen infra-red cameras (100Hz) and synchronized with GRF(ground reaction force) data(1000Hz). Ten male soccer players performed a drop landing with single-leg and bi-legs on the 30cm height box. Dependent variables were the CoM trajectory and the Joint Moment. Statistical computations were performed using the paired t-test and ANOVA with Turkey HSD as post-hoc. Results : The dominant leg was confirmed to show a significant difference between the left leg and right leg as the inverted pendulum model during Drop Landing(Phase 1 & Phase 2). One-leg drop landing type had the higher CoM displacement, the peak of joint moment with the shock absorption than Bi-leg landing type. As a lower extremity joint kinetics analysis, the knee joint showed a function of shock absorption in the anterior-posterior, and the hip joint showed a function of the stability and shock absorption in the medial-lateral directions. Conclusion : These findings indicate that the instant equilibrium of posture balance(phase 1) was assessed by the passive phase as Class 1 leverage on the effect of the stability of shock absorption(phase 2) assessed by the active phase on the effect of Class 2 leverage. Application : This study shows that the cause of musculo-skeletal injuries estimated to be focused on the passive phase of landing and this findings could help the prevention of lower damage from loads involving landing related to the game of sports.

• Fashion & Textile Research Journal
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• v.11 no.5
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• pp.741-752
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• 2009

As a major obstacle to active online purchase at the level of consumer in China, distrust is raised in this study. Most of previous studies showed that trust is a major variable to cause a relational unity between company and consumer, on the other hand, this study attempts to show that according to the two dimensional point of view regarding trust each dimension of both trust and distrust distinctly contributes to marketing achievement. Interaction, perceived popularity, information usefulness, perceived security risk and perceived dealing risk were created as preceding variable, trust and distrust were constituted as parameter and relation absorption and purchase intention as consequential variable. These variables were analyzed with structural equation modeling (SEM) in LISREL 8.3 program. The results for this study are as follows. First, relation between exchange actors in marketing is divided into two concepts of trust and distrust differently from the previous studies. On the assumption that trust and distrust might exist simultaneously and they would distinctly have an influence on marketing consequency such as relation absorption and repurchase intention, it is identified that trust and distrust are a different dimension in online context. Second, the formative factor of online trust-distrust is identified and it is shown what relationship between internet shopping mall and relation absorption and foregoing purchase intention resulting from online trust-distrust exists. Third, it is shown that in online context the formative factor of online trust-distrust is distinctly contributed to relation absorption and repurchase intention. It is suggested that trust needs to be managed two-dimensionally separating from trust and distrust. Fourth, it is shown that both trust and distrust factor in terms of relation absorption and repurchase intention of consumer in internet shopping mall are significant variables. Trust is linked with repurchase intention through relation absorption, however, distrust is not directly linked with repurchase intention through relation absorption. Thus, the ripple effect of distrust appears to be much higher than that of trust.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.181-187
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• 2018

In this paper, sound absorption of micro-perforated elastic plates installed in an impedance tube of a circular cross-section is discussed using an analytic method. Vibration of the plates and sound pressure fields inside the duct are expressed in terms of an infinite series of modal functions, where modal functions in the radial direction is given in terms of the Bessel functions. Under the plane wave assumption, a low frequency approximation is derived by including the first few plate modes, and the sound absorption coefficient is given in terms of an equivalent impedance of a single surface. The sound absorption coefficient using the proposed formula is in excellent agreement with the result by the FEM (Finite Element Method), and shows dips and peaks at the natural frequencies of the plate. When the perforation ratio is very small, the sound absorption coefficient is dominated by the vibration effect. However, when the perforation ratio reaches a certain value, the sound absorption is mainly governed by the rigid MPP (Micro-Perforated Plate), while the vibration effect becomes very small.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.124-129
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• 2008

The objectives of this paper are to examine the effect of nano-particles on the pool type absorption heat transfer enhancement and to find the optimal conditions to design a highly effective compact absorber for $NH_3/H_2O$ absorption system. The effect of $Al_2O_3$ and CNT particles on the absorption performance is studied experimentally. The experimental ranges of the key parameters are 20% of $NH_3$ concentration, $0{\sim}0.08%$ (volume fraction) of CNT particles, and $0{\sim}0.06%$ (volume fraction) of $Al_2O_3$ nano-particles. For the $NH_3/H_2O$ nanofluids, the heat transfer rate and absorption rate with 0.02 vol% $Al_2O_3$ nano-particles were found to be 28.9% and 17.8% higher than those without nano-particles, respectively. It is recommended that the concentration of 0.02 vol% of $Al_2O_3$ nano-particles be the best candidate for $NH_3/H_2O$ absorption performance enhancement.

• The Journal of the Korea Contents Association
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• v.22 no.2
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• pp.617-629
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• 2022

This study empirically analyzed the mediating effect of technology absorption capacity in the relationship between technological innovation of ship parts manufacturing companies on business performance. Through this, it will be possible to provide implications for improvement plans for management strategy establishment related to technology development in the future. In order to achieve the purpose of this study, R&D, marketing, production·A total of 362 people working in manufacturing and finance/accounting departments were selected as subjects for this study. As a result of this study, it was found that technological innovation and technology absorption capacity of ship parts manufacturing companies have a positive (+) effect on business performance. The conclusion based on these research results is that the potential absorption capacity and realized absorption capacity constituting technology absorption capacity are judged to be the main key factors between technological innovation and management performance, such as continuous technological capacity accumulation. From a practical point of view, the ship parts manufacturing industry needs to focus on its ability to absorb smart parts process technology.