• 수산해양기술연구
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• 제48권1호
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• pp.82-90
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• 2012

Four different buildings having various wall construction are analyzed for the effect of wall mass on the thermal performance and inside building air and wall temperature transient and also for calculating the energy consumption load. This analytical study was motivated by the experimental work of Burch et al. An analytical solution of one-dimensional, linear, partial differential equations is obtained using the Laplace transform method, Bromwich and modified Bromwich contour method. A simple dynamic model using steady state analysis as simplified methods is developed and results of energy consumption loads are compared with results obtained using the analytical solution. Typical Meteorological Year data are processed to yield hourly average monthly values. This study is conducted using weather data from two different locations in Korea: Daegu having severe weather in summer and winter and Jeju having mild weather almost all year round. There is a significant wall mass effect on the thermal performance of a building in mild weather condition. Buildings of heavyweight construction with insulation show the highest comfort level in mild weather condition. A proportional controller provides the higher comfort level in comparison with buildings using on-off controller. The steady state analysis gives an accurate estimate of energy load for all types of construction. Finally, it appears that both mass and wall insulation are important factors in the thermal performance of buildings, but their relative merits should be decided in each building by a strict analysis of the building layout, weather conditions and site condition.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권7호
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• pp.376-383
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• 1999

The piezoelectric transformer (PT) is an electro-mechanical device that transfers electrical energy through a mechanical vibration. In this paper, a PT operating in the contour vibration mode is introduced for an application of fluorescent lamp ballast. Utilizing its inherent characteristics of the LC resonator and a high voltage gain to ignite the lamp in light load condition, an investigation of a power piezoelectric transformer as a potential component for a fluorescent lamp ballast is discussed. PT is easy to be produced in mass and reduces the cost of the ballast. The modified equivalent circuit model of the PT considering the operating current level is derived to design the fluorescent lamp ballast. This model describes the voltage gain of the PT in wide load variations and various input current levels. The experimental and simulation results are provided to verify theoretical analysis. The power capacity of the currently developed PT is relatively low (15W), but it can be increased by adopting a multi-layer structure and is currently under investigation. It is also possible to parallel the PT for higher power processing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1272-1275
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• 2007

The HDD (hard disk drive) using Load/Unload (L/UL) technology includes the benefits which are increased areal density, reduced power consumption and improved shock resistance than those of contact-start-stop (CSS). Dynamic L/UL has been widely used in portable hard disk drive and will become the key technology for developing the small form factor hard disk drive. Main design objectives of the L/UL mechanisms are no slider-disk contact or no media damage even with contact during L/UL, and a smooth and short load and unload process. In this paper, we focus on state matrix, pitch static attitude (PSA), roll static attitude (RSA), loading/unloading contour (LC/ULC), impact force and contact. Stability of slider is mainly determined by PSA and RSA. State matrix by PSA and RSA is also important indicator. Therefore we analyze state matrix of SFF HDD suspension through the LC/ULC.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.35-40
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• 2001

The exact solution of strength of reinforced concrete RC columns subjected to axial compression combined with biaxial bending needs trial and adjustment procedure to find the depth and inclination of the neutral axis. Thus, approximate methods of analysis and design for biaxial bending are used in practice. Load contour interprets the relation of biaxial bending and equivalent uniaxial bending by u factor which is related to material properties and column shapes. The purpose of this study is to investigate the behavior of high strength RC columns subjected to the combined axial compression and biaxial bending. Fifteen test specimens with dimensions of 200mm$\times$200mm and 4-Dl3 longitudinal steel were examined. The variable of the test is compressive strength of concrete (350, 585, 650kgf/$cm^{2}$), compression load ratio (0.2$P_{o}}$, 0.35$P_{o}}$, 0.5$P_{o}}$), and inclination of loading ($\theta$=0, 22.5, $45^{\circ}$). Test results of coefficient $\alpha$ depending on the compressive strength of concrete are compared with ACI code.

• 한국기계가공학회지
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• 제8권2호
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• pp.40-45
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• 2009

This study is analyzed by stress contour of automotive tire at contact on road surface. Maximum equivalent stress as 61200Pa is shown on the lower mid part in case of tire contacted on road surface. As the air pressure of tire increases, maximum total deformation as 5mm is shown on the side part of tire. It can be shown that the side part of tire is unstabilized. There is no load effect on tire at its upper and lower directions. When the moment applied on the side of tire is increased 1.4 times as its value, the value of maximum principal stress is increased 1.4 times. The stress at the tire is in proportion to the moment applied on the its side. The tire tends to incline toward its side by this moment.

• Wind and Structures
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• 제8권3호
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• pp.147-161
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• 2005

Two identical tall building models with square cross-sections are experimentally studied in a wind tunnel with high-frequency-force-balance (HFFB) technique to investigate the interference effects on wind loads and dynamic responses of the interfered building. Another wind tunnel test, in which the interfered model is an aeroelastic one, is also carried out to further study the interference effects. The results from the two kinds of tests are compared with each other. Then the influences of turbulence in oncoming wind on dynamic interference factors are analyzed. At last the artificial neural networks method is used to deal with the experimental data and the along-wind and across-wind dynamic interference factor $IF_{dx}$ & $IF_{dy}$ contour maps are obtained, which could be used as references for wind load codes of buildings.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.902-906
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• 2008

The linear motors are easily affected by load disturbance, force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbance. For highspeed/high-accuracy position control of a linear-motor-driven two axes, a nonlinear adaptive controller including a cross-coupling algorithm is designed in this paper. The nonlinear effects such as friction and force ripple are estimated and compensated. An enhanced approach for cross-coupling algorithm is proposed to effectively improve the biaxial contour accuracy with the closed-loop stability. The proposed controller is evaluated through the computer simulations.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.147-158
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• 2015

Elements used in steel structures may be considered as an assembly of number of thin flat walls. Local buckling of these members can limit the buckling capacity of axial load resistance or flexural strength. We can avoid a premature failure, caused by effects of local buckling, by limiting the value of the wall slenderness which depend on its critical buckling stress. According to Eurocode 3, the buckling stress is calculated for an internal wall assuming that the latter is a simply supported plate on its contour. This assumption considers, without further requirement, that the two orthogonal walls to this wall are sufficiently rigid to constitute fixed supports to it. In this paper, we focus on webs of steel profiles that are internal walls delimited by flanges profiles. The objective is to determine, for a given web, flanges dimensions from which the latter can be considered as simple support for this web.

• Archives of Plastic Surgery
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• 제51권2호
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• pp.163-168
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• 2024

Background The study determined to compare the clinical outcomes of traditional gold weight implantation for the correction of paralytic lagophthalmos with those of a newly designed model. Methods In this retrospective cohort study, we enrolled 30 patients (76% females; average age 60.8 ± 12 years) with facial palsy who underwent implantation of either the traditional pretarsal gold weight (PT group; n = 15) or a new supratarsal model (ST group; n = 15) from May 2014 to April 2019. The main outcome measures were the 12-month postoperative weight prominence, weight migration, improvement of lagophthalmos, upper eyelid contour, and upper eyelid ptosis. The secondary outcome was long-term (24 months) reoperative rate. Results The new model group had significantly better eyelid contour (risk ratio [RR] 3.16, 95% confidence interval [CI] 1.62-6.15, p = 0.001), less weight prominence (RR 1.74, 95% CI 1.13-2.70, p = 0.013), less weight migration (RR 1.31, 95% CI 1.12-1.54, p = 0.001), and less eyelid ptosis (RR 2.36, 95% CI 1.21-4.59, p = 0.011) than the traditional model group. Improvement of lagophthalmos was not statistically significant between the two groups (RR 1.44, 95% CI 0.72-2.91, p = 0.303). The 24-month reoperative rate was 53.3% in the PT group versus 13.3% in the ST group (RR 2.00, 95% CI 1.15-3.49, p = 0.015). Conclusion The newly designed supratarsal gold weight showed superior postoperative outcomes than the standard traditional model.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1986-1996
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• 2003

Methodology based on the elastic-plastic fracture mechanics has been widely accepted in predicting the critical crack length(CCL) of pressure tubes of CANDU nuclear plants. A conservative estimate of CCL is obtained by employing the J-resistance curves measured with the specimens satisfying plane strain condition as suggested in the ASTM standard. Due to limited thickness of the pressure tubes the curved compact tension(CT) specimens taken out from tile pressure tube have been used in obtaining J-resistance curves. The curved CT specimen inevitably introduce slant fatigue crack during precracking. Hence, effect of specimen geometry and slant crack on J-resistance curve should be explored. In this study, the difference of J integral values between the standard CT specimens satisfying plane strain condition and the nonstandard curved CT with limited thickness (4.2mm) is estimated using finite element analysis. The fracture resistance curves of Zr-2.5Nb obtained previously by other authors are critically discussed. Various finite element analysis were conducted such as 2D analysis under plane stress and plane strain conditions and 3D analysis for flat CT, curved CT with straight crack and curved CT with slant crack front. J-integral values were determined by local contour integration near the crack tip, which was considered as accurate J-values. J value was also determined from the load versus load line displacement curve and the J estimation equation in the ASTM standard. Discrepancies between the two values were shown and suggestion was made for obtaining accurate J values from the load line displacement curves obtained by the curved CT specimens.