• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.36 no.1
• /
• pp.70-73
• /
• 1991

Stomatal frequency and size of rice plant grown in the different silicon levels of the culture solution in phytotron were observed on both side of the 7th leaf blade. By the application of silicate, stomatal frequency and rates of stoma cell area to the leaf area were remarkably reduced in Milyang 23. It could be considered as favorable characteristics which might be reduced the transpira-tion rate from leaf surface of rice plant besides presence of cuticle-silica double layer in leaf surface.

• The Korean Journal of Applied Statistics
• /
• v.21 no.5
• /
• pp.783-789
• /
• 2008

We investigate the effects of the misspecification of cointegrating(CI) ranks at other frequencies on the inference of seasonal models at the frequency of interest; our study includes tests for CI ranks and estimation of CI vectors. Earlier studies focused mostly on a single frequency corresponding to one seasonal root at a time, ignoring possible cointegration at the remaining frequencies. We investigate the effects of the mis-specification, especially in finite samples, by adopting Gaussian reduced rank(GRR) estimation by Ahn and Reinsel (1994) that considers cointegration at all frequencies of seasonal unit roots simultaneously. It is observed that the identification of the seasonal CI rank at the frequency of interest is sensitive to the mis-prespecification of the CI ranks at other frequencies, mainly when the CI ranks at the remaining frequencies are underspecified.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.5
• /
• pp.615-623
• /
• 2016

The paper describes a hysteretic buck converter including a differentiator and an adaptive hysteresis window controller. Differentiating the feedback signal achieves ultra-fast switching of the buck converter. The adaptive hysteresis window control allows a monotonous operation with predictable noise spectrum, and gives way to efficient design for variable supply and output voltages. The measurement results in a $0.13-{\mu}m$ CMOS process indicated that the switching frequency became double times higher, and the voltage ripple was reduced by up to 69%. They also indicated that the normalized switching frequency variation was reduced by 74% with variable $V_{DD}$ and by 63% with variable $V_{OUT}$. The power efficiency was improved by 3.5% depending on loading condition.

• Biomedical Science Letters
• /
• v.19 no.1
• /
• pp.55-60
• /
• 2013

This study was to know the effects of massage on the back region in order to reduce stress in middle age women. To investigate the effects of massage to the stress levels of middle aged women, we evaluated blood pressure (BP), heart rate variability (HRV), and ultrasonography before and after back massage. The blood pressure after massage was reduced when compared to that of pre-massage. The HRV spectrum analysis was used Frequency domain analysis such as Mean HRV, normalized low frequency (norm LF), norm high frequency (norm HF), and LF/HF ratio. Post-massage BP tended to be low, but not statistical significant. After Massage, the Mean HRV, norm LF, and LF/HF ratio were significantly reduced, while norm HF was significantly increased as compared with pre-massage. The muscle layer and fat layer were significantly diminished by massage. The study was suggested that massage may be an effective treatment for relief of stress.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.8
• /
• pp.995-999
• /
• 2014

In this paper, a new size-reduction approach for branch-line coupler is introduced which uses parallel end-shorted coupled lines with lumped capacitors. The characteristic of the new design was analyzed using even-odd mode method, and simulated on HFSS before fabricated on the FR4 epoxy glass cloth copper-clad plat (CCL) PCB substrate at center frequency of 1 GHz. The electrical length of transmission line was reduced to 15 degrees, therefore the size of branch-line coupler was largely reduced approximately maintaining the same characteristic around the stable center frequency. The insertion loss of the branch-line coupler filter was -4.39 dB. The size of the overall hybrid is $20mm{\times}20mm$. Measurements results were well agreed with the simulated ones.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.499-504
• /
• 2004

The purpose of this study is to investigate a investigating of a floor-impact isolation system using damping materials in apartment buildings. The stiffness elastic modulus(k) by puls impact forces were calculated loss factor by Hilbert transforms. It is absolved that natural frequency was moved floor shock-absorbing materials and the impact force was reduced by floor panel. The slab was constructed by damping materials. As towards a result, the system showed inverse A 45dB by heavy weight-impact noise and inverse A 52dB by light-impact noise. High frequencies impact-noise can be reduced by upgrading naturial frequency of vibration and noise in the system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.6
• /
• pp.546-552
• /
• 2011

In this study, noise sources of a reducer which is combined a spiral bevel gear and a planocentric gear are identified by experimental method and the noise was reduced by the structure modification of the reducer. In order to identify the noise sources, noise and vibration signals were measured by microphone and accelerometer and these signals were analyzed with waterfall plot. In addition, the frequency response functions were obtained to prove the noise and vibration sources. It was found that the resonance was generated by the gear mesh frequencies and natural frequency of the reducer. The noise of the reducer could be reduced by structure modification.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.222-227
• /
• 2005

A Flapping foil produces an effective angle of attack, resulting in a normal force vector with thrust and lift components, and it can be expected to be a new highly effective propulsion system. A heaving foil model was made and it was operated within a circulating water channel at low Reynolds numbers. The unsteady thrust and lift acting on the heaving foil were measured simultaneously using a 6-axis force sensor based on force and moment detectors. We have been examined various conditions such as heaving frequency and amplitude in NACA 0010 profile. The results showed that thrust coefficient and efficiency increased with reduced frequency and amplitude. We also presented the experimental results on the unsteady fluid forces of a heaving foil at various parameters.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.51-56
• /
• 2011

In this study, noise sources of a reducer which is combined a spiral bevel gear and a planocentric gear are identified by experimental method and the noise was reduced by the structure modification of the reducer. In order to identify the noise sources, noise and vibration signals were measured by microphone and accelerometer and these signals were analyzed with waterfall plot. In addition, the frequency response functions were obtained to prove the noise and vibration sources. It was found that the resonance was generated by the gear mesh frequencies and natural frequency of the reducer. The noise of the reducer could be reduced by structure modification.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.5
• /
• pp.541-549
• /
• 2007

In the case of control for mechanical systems, it is highly useful to be able to provide a compact model of the mechanical system to control engineers using the smallest number of state variables, while still providing an accurate model. The reduced mechanical model can then be inserted into the complete system models and used for extended system-level dynamic simulation. In this paper, moment-matching based model order reductions (MOR) using Krylov subspaces, which reduce the number of degrees of freedom of an original finite element model via the Arnoldi process, are presented to study the eigenvalue and frequency response problems of a HDD actuator and suspension system.