• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.169-174
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• 2007

Adopting articulated bogie system, the HSR350x and KTX have similar physical mechanical characteristic, but they show different dynamic characteristics due to different position of suspensions and those physical properties. The low level vibration frequency which effects on the ride comfort of passengers and the high level vibration frequency which is related to noise of vehicle have been measured by accelerometers mounted on Wheel sets, Bogies and Car bodies to analysis the dynamic characteristics of the High-Speed Trains. The KTX number 36 is utilized to measure the lateral and vertical acceleration value of car body, and total measurement system of HSR350x have been used to acquire acceleration data. The sampling frequency of data is 500Hz generally, but the Car body at TT2 of HSR350 has 1000Hz exceptionally.

• Journal of Welding and Joining
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• 제22권4호
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• pp.65-72
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• 2004

The aim of this study is to investigate the optimum drawing parameter for BAS111 welded tubes. The BAS111 aluminium alloy tubes with 25.4mm in external diameter and 1.5mm in thickness for heat-exchangers were manufactured by high frequency induction welding with the V shaped convergence angle 6.8$^{\circ}$ and power input 50㎾. With increasing the reduction of area (1.6, 5.8, 11.5, 14.2, 18.5, 22.5%) by drawing, tensile strength was increased and elongation was decreased. With increasing the reduction of area by drawing, hardness in weld metal increased rapidly, while that of base metal increased slowly. In the specimen with the outer diameter smaller than 22mm, hardness of weld metal was higher than that of base metal. The optimum drawing parameter of area reduction was estimated about 15% because of the work hardening of welds.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.127-133
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• 2013

We examined the scaling effects of a number of gate_fingers (N) and gate_widths (w) on the high-frequency characteristics of $0.1-{\mu}m$ metamorphic high-electron-mobility transistors. Functional relationships of the extracted small-signal parameters with total gate widths ($w_t$) of different N were proposed. The cut-off frequency ($f_T$) showed an almost independent relationship with $w_t$; however, the maximum frequency of oscillation ($f_{max}$) exhibited a strong functional relationship of gate-resistance ($R_g$) influenced by both N and $w_t$. A greater $w_t$ produced a higher $f_{max}$; but, to maximize $f_{max}$ at a given $w_t$, to increase N was more efficient than to increase the single gate_width.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.527-528
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• 2006

Nanostructured Alumina - 20 vol% 3YSZ composites powder were synthesized by wet-milling technique. The starting materials were a mixture of Alumina micro-powder and 3YSZ nano-powders. Nano-crystalline grains were obtained after 24 h milling time. The nano-structured powder compacts were then processed to full density at different temperatures by high-frequency induction heat sintering (HFIHS). Effects of temperature on the mechanical and microstructure properties have been studied. $Al_2O_3-3YSZ$ composites with higher mechanical properties and small grain size were successfully developed at relatively low temperatures through this technique.

• Wind and Structures
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• 제18권4호
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• pp.375-389
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• 2014

The high-frequency force-balance (HFFB) technique and its subsequent improvements are reviewed in this paper, including a discussion about nonlinear mode shape corrections, multi-force balance measurements, and using HFFB model to identify aeroelastic parameters. To apply the HFFB technique in engineering practice, various validation studies have been conducted. This paper presents the results from an analytical validation study for a simple building with nonlinear mode shapes, three experimental validation studies for more complicated buildings, and a field measurement comparison for a super-tall building in Hong Kong. The results of these validations confirm that the improved HFFB technique is generally adequate for engineering applications. Some technical limitations of HFFB are also discussed in this paper, especially for higher-order mode response that could be considerable for super tall buildings.

• 한국의류학회지
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• 제25권6호
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• pp.1025-1036
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• 2001

This paper explores the effects of price discount frequency on consumer evaluation of clothing brand equity as well as the impact on consumers who exhibit different consumer characteristics. Following a preliminary investigation, two clothing brand groups were identified according to the frequency of their price discounts, one with a high frequency of price discounts, the other with a low frequency. Each brand group consisted of three women's clothing brands. A questionnaire was developed and administered to 351 females between the ages of nineteen and thirty-four in October 2000. The questionnaire included questions on evaluations on clothing brand equity (i.e., perceived quality, brand image, perceived value, reliability and brand knowledge), on consumer characteristics (i.e., clothing knowledge, clothing evaluative criteria, price perception and demographic characteristics), as well as on price discount frequency. Statistical tests, such as factor analysis. t-test and pearson's correlation, were used to analyze the data. Results of this research showed that price discount frequency negatively impacted consumer perception of clothing brand equity. The negative influence was particularly strong on the perceived quality and brand image dimensions of brand equity. The findings also suggested the effect of price discount frequency on consumer assessment of clothing brand equity was related to consumer characteristics as well. The equity of the clothing brand group with a low frequency of price discounts was positively related to clothing knowledge, price-quality inference, price-prestige inference, sale prone-ness. price mavenism, valuing the fashionable and symbolic uses of clothing and family income. On the other hand, it was negatively related to low price consciousness. The equity of the clothing brand group with a high frequency of price discounts was positively related to utilitarian economic aspects of clothing values as well as to low price consciousness. To establish and maintain high brand equity, marketers must pay attention to the frequency of price discount as it may have a negative impact on clothing brand equity.

• 한국진공학회지
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• 제9권2호
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• pp.167-171
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• 2000

AlGaAs/GaAs HBT의 동작특성에 미치는 에미터 구조의 영향을 조사하였다. 에미터의 크기 변화에 의해 차단주파수와 최대공진주파수가 변화하였으며, 이는 에미터 구조에 따라 저항과 접합용량이 변하기 때문이다. 또한 에미터의 주변길이와 접합면적도 HBT의 고주파 특성에 영향을 미치는 것을 알 수 있다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 춘계학술대회
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• pp.172-175
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• 2004

This paper analyzes the effects of Ge profiles shape of SiGe heterojunction bipolar transistors (HBT's) for high frequency application. Device simulations using ATLAS/BLAZE for the SiGe HBT with trapezoidal or triangular Ge profile are carried out to optimize the device performance. An HBT with $15\%$ triangular Ge profile shows higher cut-off frequency and DC current gain than that with $19\%$ trapezoidal Ge profile. The cut-off frequency and DC gain are increased from 42GHz to 84GHz and from 200 to 600, respectively. The SiGe HBT has been fabricated using a production CVD reactor.

• Journal of Information Processing Systems
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• 제19권3호
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• pp.275-288
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• 2023

Many image edge details are easily lost in the image denoising process, and the smooth image regions are prone to produce jagged. In this paper, we propose a wavelet-based image global k- singular value decomposition variational method to remove image noise. A layer of wavelet decomposition is applied to the noisy image first. Then, the image global k-singular value decomposition (IGK-SVD) method is used to remove the random noise of low-frequency components. Furthermore, a constructed variational denoising method (VDM) removes the random noise in the high-frequency component. Finally, the denoised image is obtained by wavelet reconstruction. The experimental results show that the proposed method's peak signal-to-noise ratio (PSNR) value is higher than other methods, and its structural similarity (SSIM) value is closer to one, indicating that the proposed method can effectively suppress image noise while retaining more image edge details. The denoised image has better denoising effects.

• 대한지역사회영양학회지
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• 제3권5호
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• pp.685-694
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• 1998

This cross-sectional study was conducted to describe the changes of plasma cardiovascular disease(CVD) risk factors in Korea. Overnight fasting plasma levels of total cholesterol, high density lipoprotein(HDL)-cholesterol, triacylglycerol and glucose were analyzed. Blood pressure and anthropometric data were also measured. Health practice factors such as smoking status, alcohol consumption and frequency fo exercise were evaluated by a self-administered questionnaire. Questions regarding dietary habits and food preferences were also asked. Seventy eight percent of the subjects had more than one CVD risk factor. Plasma total cholesterol, triacylglycerol, and fasting blood glucose were significantly increased according to the subjects body mass index$(kg/m^2$, BMI), whereas HDL-cholesterol, low density lipoprotein(LDL)-cholesterol and blood pressure showed no significant differences with BMI. Current smokers had significantly high plasma total cholesterol, LDL-cholesterol and triacylglycerol levels. Alcohol consumption significantly increased plasma total cholesterol and fasting blood sugar, but regular exercise had no effects on the plasma CVD risk factors. Overeating and frequency of fast food consumption were positively correlated with the CVD risk score, whereas intake of grains, meats and vegetables were negatively correlated with that score. A stepwise multiple regression analysis was performed to examine the effects of specific dietary factors on plasma lipid levels. For plasma total cholesterol level, the frequency of fast food intake explained 8% of the variance, followed by habitual overeating, frequency of grain intake and high cholesterol food intake(Model $R^2$=22.4%). For plasma triacylglycerol level, preference of oily foods accounted for 7.5% of the variance, followed by eating breakfast, preference of fruit and frequency of grain intake(Model $R^2$=22.0%). The findings suggest that intervention programs to reduce the risk of CVD should focus on health practice through reducing BMI, smoking cessation and moderate or no alcohol drinking. Moreover, desirable dietary habits such as eating breakfast, not overeating and reduced intake of fast food may improve CVD risk.