• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.169-174
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• 2005

Current information storage devices read/write data on the rotating disk. The axial vibration of a rotating disk should be suppressed for the successful operation of the device. Information storage devices widely used in these days adopt relatively thick disk which is stiff enough to suppress axial vibration under allowable limit. However, the thickness of the disk is going to be thinner and thinner as the small form factor of the devices is getting preferred by the consumer. In this study, a stabilizer system, which is composed with 8 air bearings, is proposed for suppressing the axial vibration of a $95{\mu}m$ thick PC disk in a non-contacting manner. The performance of the stabilizer system is simulated by numerical computation and then confirmed its results through a series of experiment. A thin and flexible disk has various vibration modes when it rotates in high speed. The stabilizer system generates positive as well as negative pressure due to the rotation of flexible disk so that the force due to the pressure distribution pushes and pulls rotating disk in a non-contacting manner. The balance between positive and negative pressure forces can be obtained by adjusting the area and the slope of the air bearing surface. The axial vibration of the flexible disk of 120mm diameter is suppressed successfully from over $1000{\mu}m$ to $30{\mu}m$ peak-to-peak value at the rotational speed of 5,000rpm.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.9_10 s.157
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• pp.1485-1493
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• 2006

This study was to investigate the effect of different scouring methods on mechanical properties and appearance of lyocell. Two different scouring methods were adopted for the study; one was the traditional scouring with alkali and the other was enzymatic scouring. Enzymatic scouring was carried with four different enzymes; C1 : Cellusoft L, C2 : Cellusoft UL, D1 : Denimax 992L, D2 : Denimax Acid XCL. The mechanical properties of scoured lyocell were measured using KES-FB. The appearance of scoured samples was analyzed by 3D CAD SYSTEM of i-Designer. While the untreated fabric showed the best linearity because it is stiff, alkali treated samples showed the worst dimensional stability and distorted easily. Enzyme treated samples, especially C1 treated samples showed the best dimensional stability. In addition, enzyme treated samples showed low bending rigidity compared to the alkali treated samples. It means that the enzyme treated samples are more flexible than alkali treated samples. However, the smoothness of the sample's surface treated by either of methods did not show much difference. From the study, it was suggested that the enzymatic scouring for lyocell could help to gain natural silhouette.

• Journal of Biosystems Engineering
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• v.31 no.4 s.117
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• pp.342-348
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• 2006

Aerial application using an unmanned agricultural helicopter became necessary for both labor saving and timely spraying. In the previous paper, a rotor system was developed and lift capability was evaluated. The experimental results were compared with simulated predictions using the CFD-ACE program. From the simulation, the relative velocity on the top surface of the blade airfoil increased, resulting in the pressure drop. The CFD analyses were revealed that a drag resistance on the leading edge of the airfoil, a wake at the trailing edge, and a positive pressure underneath the bottom surface were observed. As the results of the simulation, total lifts of 56.8, 74.4 and $95.0kg_f$ were obtained at the 6, 8 and $10^{\circ}$ of AAT (angle of attack), respectively. The simulation results agreed reasonably up to $10^{\circ}$ of AAT. However, at a greater AAT $(<12^{\circ})$ the simulated total lift continuously increased to $105kg_f$, comparing with a decreasing experimental total lift due to the lack of engine power. At a stiff angle of $18^{\circ}$ AAT, a wake was observed at the trailing edge of the airfoil. A rated operating condition determined from the previous paper was also verified through the simulation.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.527-538
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• 2017

The evaluation of the loss-of-support conditions of frictional beam-to-column connections using simplified numerical models describing the transverse response of a portal-like structure is presented in this paper considering the effects of the seismic-hazard disaggregation. Real earthquake time histories selected from European Strong-motion Database (ESD) are used to show the effects of the seismic-hazard disaggregation on the beam loss-of-support conditions. Seismic events are classified according to different values of magnitudes, epicentral distances and soil conditions (stiff or soft soil) highlighting the importance of considering the characteristics of the seismic input in the assessment of the loss-of-support conditions of frictional beam-to-column connections. A rigid and an elastic model of a frame of a precast industrial building (2-DoF portal-like model) are presented and adopted to find the minimum required friction coefficient to avoid sliding. Then, the mean value of the minimum required friction coefficient with an epicentral distance bin of 10 km is calculated and fitted with a linear function depending on the logarithm of the epicentral distance. A complete parametric analysis varying the horizontal and vertical period of vibration of the structure is performed. Results show that the loss-of-support condition is strongly influenced by magnitude, epicentral distance and soil conditions determining the frequency content of the earthquake time histories and the correlation between the maxima of the horizontal and vertical components. Moreover, as expected, dynamic characteristics of the structure have also a strong influence. Finally, the effect of the column nonlinear behavior (i.e. formation of plastic hinges at the base) is analyzed showing that the connection and the column are a series system where the maximum force is limited by the element having the minimum strength. Two different longitudinal reinforcement ratios are analyzed demonstrating that the column strength variation changes the system response.

• The Research Journal of the Costume Culture
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• v.17 no.6
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• pp.1009-1020
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• 2009

This study aims to express the androgynous image via shirts as a fashion item. Shirts are widely worn as a fashion item regardless of sex and age, with growing importance as a casual outer, with the increase in leisure activities driven by the recent implementation of the 5-Day Work Week system in Korea. As for the theoretical background, the study was reviewed previous studies of books, thesis, a series of publication, and the Internet sites on this topic. Through a careful analysis of these previous studies, it designed and made shirts that inspired by androgynous image. Conclusions of this study are as follows: First, the study found that meanings of symbolism in clothing continue to change, not fixed at all, depending on historic and cultural environments, and so does symbolism for femininity and masculinity of clothing. Second, shirts are widely worn as a fashion item regardless of sex and age, with growing importance as a casual outer, with the increase in leisure activities driven by the recent implementation of the 5-Day Work Week system in Korea. Third, two patters were used for the work in this study in order to emphasize its form, along with mono color white and stripe patterns. For materials, cotton and blend as a most basic material for a shirt were used with unique variations in the form. Fourth, decorative details or trimming such as ribbon tying methods, shirring, attaching in layers, and irregular pleading widely used for women's wear were applied, and silhouettes with strong drape feelings were used to add feminine feature to men' shirts, in an effort to propose a fashion design of the androgynous look. Fifth, clothes proposed in this study are different from feminine clothing item blouse, because they are androgynous shirts mixing masculinity and femininity. Stiff pads were used in collars and cuffs characteristics of men's traditional shirts to maintain masculinity of a shirt, and design was developed by adding feminine decorative elements, which is different from women's blouse.

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.357-362
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• 2006

This study is to evaluate the objective sensibility of the commercial lining fabrics. Five kinds of the linings were collected by adding taffetas with four kinds of fibers (polyester, nylon, rayon, and acetate) to one polyester stretch fabric. The six basic mechanical and hand properties were studied by using KES-FB system (Kawabata Evaluation System). The result of measuring the mechanical properties shows that polyester has high bending rigidity (B), that polyester-stretch has a high value of linearity of load-extension curve (LT), tensile energy (WT), tensile resilience (RT), and coefficient of friction (MIU) and a low value of bending rigidity(B), shear property, and geometrical roughness (SMD). The nylon has a high value of bending rigidity (B), shear property, and compression resilience (RC). The rayon has a high value of coefficient of friction (MIU) and linearity of compression-thickness curve (LC) and a low value of shear property, and the acetate has a low value of shear property. The result of hand value shows that polyester, nylon, and acetate are a high value of KOSHI (stiffness), NUMERI (smoothness), and FUKURAM (fullness & softness), and they feel stiff and massive, that rayon has a low value of NUMERI and FUKURAMI. The total result of hand value shows that polyester taffeta and polyester stretch fabric are about the same as the best material for the lining of a woman's dress for spring and summer, and the next thing is acetate, but nylon and rayon are somewhat inferior materials. This provides a fundamental data for the comfortable clothing production of a higher value-added product through the study on the mechanical and hand properties of the lining as well as the right side of fabrics.

• Earthquakes and Structures
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• v.9 no.3
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• pp.603-623
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• 2015

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.3
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• pp.148-154
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• 1998

Gubong gold-mine, previously one of the largest gold mines in Korea, is located at the mid-west of the South Korea. In the areas nearby the mine, the shallow groundwater was the major source for domestic and farming water-supply. Soil contamination by Cd, Cu, Pb and Zn was previously known in this area. This study is objected to identify quality of the shallow groundwater, possibly affected by the mine tailings. Samples were collected from a nearby stream, shallow groundwater and seepage from the tailings. Chemical analysis for the water quality includes major cations such as Na, K, Ca, and Mg, anions as F, Cl, NO$_3$, SO$_4$, HCO$_3$, and trace elements as Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd, Pb, Se, As, Hg. Water types could be drawn into four groups from the plots of Piper, Stiff diagrams and cluster analysis. SAR-Conductivity plot indicates the water does not pose either alkalinity or salinity hazards for irrigation. Major contaminant in groundwater appeared to be arsenic, released from arsenopyrites in tailings by oxidation. Dredging of buried railing materials could stimulate the release of arsenic from the sediments to the groundwater.

• Journal of the Korean GEO-environmental Society
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• v.9 no.4
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• pp.23-36
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• 2008

Soil nailing system can be mentioned to a method of supporting as the shear strength of in-situ soils is increased by passive inclusions. In the general soil nailing system, facing walls are used in two kind of a lattice concrete block or a cast in placed concrete wall. A case of lattice concrete blocks is used in slow slopes greater than 1(V):0.7(H). Also, a case of a cast in placed concrete wall is used in steep slopes less than 1(V):0.5(H). The cast in placed concrete walls are constructed to 30 cm thick together with a shotcrete facing. In this study, the assembling soil nailing method as a new soil nailing system will be proposed. This method is assembly construction using precast concrete panels with 20 cm thick. So, the ability of construction and the quality of facings can be improved more than a conventional soil nailing system. This method can be obtained the effects that a global slope stability increase, as precast concrete panels are immediately put on cutting face after excavating a slope. In this study, confining effects of concrete panels using the assembling soil nailing system were found out by large scaled load tests. In the tests, the load-settlement relationship to an assembling soil nailing system due to the stiff facings as concrete panels appeared to be better than a typical soil nailing system with shotcrete facings.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.381-393
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• 2001

The current traffic situation in Korea can be described as rapid change in traffic volume and diversity in vehicle size from compact cars to large trucks. W-beam barrier most widely used in Korea was found not to satisfy the stiffness requirement for the Koran impact condition of 14 ton-60Km/h-15deg. and it was too stiff for small vehicles impacting with more realistic speed to satisfy the safety of vehicle occupants. To develop a guardrail system satisfying the two contradicting goals, a thrie-beam guardrail system, which had the beam thickness of 3.2mm and rubber cushions, was conceived. Even though the height of the thrie-beam(450mm) is increased by 100mm as compared to that of W-beam (350mm), there was only 2% increase in the weight of the thrie-beam. The new thrie-beam barrier system could contain more wide range of vehicle bumper heights, and showed better performance in the viewpoint of stiffness and energy absorbing capability than the W-beam system. The impact performance was evaluated from a crash test. The developed thrie-beam guardrail system satisfied all applicable criteria for NCHRP 350 test designation 3-10.