• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.40-49
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• 2008

A Frequency synthesizer for mobile-DTV applications is implemented using $0.18{\mu}m$ CMOS process with 1.8V supply. PMOS transistors are chosen for VCO core to reduce phase noise. The measurement result of VCO frequency range is 800MHz-1.67GHz using switchable inductors, capacitors and varactors. We use varactor bias technique for the improvement of VCO gain linearity, and the number of varactor biasing are minimized as two. VCO gain deterioration is also improved by using the varactor switching technique. The VCO gain and interval of VCO gain are maintained as low and improved using the VCO frequency calibration block. The sigma-delta modulator for fractional divider is designed by the co-simualtion method for accuracy and efficiency improvement. The VCO, PFD, CP and LF are verified by Cadence Spectre, and the sigma-delta modulator is simulated using Matlab Simulink, ModelSim and HSPICE. The power consumption of the frequency synthesizer is 18mW, and the VCO has 52.1% tuning range according to the VCO maximum output frequency. The VCO phase noise is lower than -100dBc/Hz at 1MHz at 1MHz offset for 1GHz, 1.5GHz, and 2GHz output frequencies.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1117-1127
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• 2012

In this paper, the monopole antenna for satisfying GSM900/DCS1800/PCS1900/UMTS2100 services is designed. We can get the characteristic of the low frequency bands by connecting the front patch to the back patch of the antenna and get the low frequency resonance band using a front patch slit. The proposed antenna total volume is $40{\times}98{\times}1.6\;mm^3$, and it is designed on the FR-4 substrate having a relative dielectric constant of 4.4. As measurement result after fabrication, showed that the resonant frequency bandwidths are 156 MHz(828~984 MHz), 708 MHz(1.476~2.184 GHz) based on the return loss of 10 dB, and the radiation patterns show as the omnidirectional shapes for the E-field and H-field. For analyzing the human effects, the proposed antenna is mounted on the mobile-phone case. The averaged peak SAR over 1 g and 10 g is simulated and measured when the input power is 0.25 W. We have checked the variation of the SAR values when the antenna is mounted 4 different directions, then checked the direction having a relatively higher SAR. The results also satisfied the limiting SAR values which are 1.6 W/kg and 2.0 W/kg averaged over 1 g and 10 g tissues respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.570-579
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• 2009

In this paper, we presented a Vt-DRO with a wide electrical frequency tuning range, using open-loop gain method. The Vt-DRO was composed of 3-stages, resonator, amplifier and phase shifter. In order to satisfy an oscillation condition, we determined magnitude and phase of each stage. The measured S-parameter of cascaded 3-stages shows open-loop oscillation condition. Also, using measured open loop group delay, we derived the relation for electrical frequency tuning range. The Vt-DRO was implemented by connecting the input and the output of the designed open-loop and resulted in closed-loop. As a results, tuning-range of Vt-DRO is 82 MHz, which is close to the predicted results for tuning voltage 0${\sim}$10 V and shows linear frequency tuning at the center frequency of 5.3 GHz. The phase noise is -104 ${\pm}$1 dBc/Hz at 100 kHz offset frequency and power is 5.86${\pm}$1 dBm respectively.

• The Journal of Korean Academy of Sensory Integration
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• v.7 no.1
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• pp.1-12
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• 2009

Objective : This study is to verify effect of a sensory integration (SI) intervention on sensory processing of children with sensory modulation disorder (SMD), and to explore how the SI intervention affect play, socialization, occupational performance and occupational satisfaction of those children. Method : Five children with developmental disabilities living in metropolitan were diagnosed as SMD by the Sensory History Interview (SHI) and Short Sensory Profile (SSP). The SMD children undergone the 48 sessions of 50 min intervention twice in a week for six months and took the Revised Knox Preschool Play Scale(RKPPS), Social maturity test, Canadian Occupational Performance Measure(COPM), and Japanese Sensory Inventory Revised(JSI-2) before- and after the intervention. The result data analyzed by the Wilcoxon matched-pair signed rank test. Results : All data of post-intervention differed significantly; RKPPS(Z=-2.023, p=.043), Social maturity test(Z=-2.023, p=.043); occupational performance(Z=-2.023, p=.043); satisfaction(Z=-2.032, p=.042); and tactile system of JSI-2(Z=-2.032, p=.042). Conclusions : The results advocate that sensory integration intervention is effective in improving tactile processing, play, socialization, occupational performance, and occupational satisfaction of child with SMD. It is found that sensory integration intervention improves not only one's occupational performance but also underlying components of the performance. In order to generalize this conclusion, further studies need to be done with more number of subjects and consideration of environmental factors. Striving for more reliable and valid methods of data collection is also suggested.

• Journal of the Korean GEO-environmental Society
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• v.10 no.7
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• pp.7-14
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• 2009

The correlation equation empirically proposed to obtain compression indexes has been proposed to conveniently obtain the value using the soil parameter that can be obtained through simple tests when the number of time of consolidation testing is low or the distribution is large but most of the analyzed regions are limited to certain regions abroad or in the country and multiple data were integrated for use in many cases, thus it is not very reasonable to apply it. Therefore, to establish a new design method considering the uncertainty of the ground, it was selected the Kwangyang port area of which the data have been collected recently thus are relatively more reliable as the subject region of the study in order to maximally reduce the uncertainty of test data. After performing the verification of the normality of the consolidation test data obtained from the selected region and the transformation of variables, a prediction formula was proposed through the regression model with the transformed variables and the proposed regression model with transformed variables was compared with existing empirical equations to verify the suitability of the proposed model formula. After analyzing, it was confirmed that the coefficient of determination was increased after the Box-Cox variable transformation, thus the explanatory power was being enhanced and through the root-mean-square-error method, it was confirmed that the proposed model formula showed the most closed value to the test value.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.9
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• pp.1339-1347
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• 2003

An experiment was conducted to investigate the effects of microbial phytase ($Natuphos^{(R)}$) supplementation in combination with carbohydrases (composed of enzymes targeted to soybean meal (SBM) dietary components such as $\alpha$-galactosides and galactomannans; $Endo-Power^{(R)}$) to corn-soybean meal based diet (CSD) and complex diet (CD) with a partial replacement of SBM with rape seed meal (RSM) and cotton seed meal (CSM) on growth performance and nutrient digestibility of growing pigs. A total of 168 growing pigs averaging $13.18{\pm}1.77kg$ of initial body weight was arranged as a $2{\times}2$ factorial design with main effects of diet types (corn-SBM based diet (CSD) and complex diets (CD; 5% of SBM was replaced with 2.5% of RSM and 2.5% of CSM in diet for phase I (0 to 3 weeks) and 6% of SBM was replaced with 3% of RSM and 3% of CSM in diet for phase II (4 to 7 weeks))) and enzyme supplementation (none and 0.1% of phytase (500 FTU/kg diet) and 0.1% of carbohydrases). The diet with enzyme application were formulated to have a 0.18% unit lower aP than diets without enzyme application. Each treatment had three replicates with 14 pigs per replicate. To determine supplementation effect of phytase and carbohydrases on ileal amino acid digestibility of SBM, RSM and CSM, a total of 18 T-cannulated pigs (initial body weight; $13.52{\pm}1.24kg$) were assigned to six dietary treatments in the present study. Dietary treatments in metabolic trial included 1) SBM diet, 2) SBM diet+with enzymes (phytase (500 FTU/kg) and carbohydrases at 0.1%, respectively), 3) CSM diet, 4) CSM diet+enzymes, 5) RSM diet and 6) RSM diet+enzymes. During whole experimental period (0 to 7 wks), there was no difference in growth performance between diets (CSD and CD). However, dietary phytase and carbohydrases supplementation significantly improved gain/feed ratio (G:F) of growing pigs. During the phase II (4-7 weeks), dietary phytase and carbohydrases supplementation significantly improved all fecal nutrient digestibilities (Dry matter (DM), gross energy (GE), crude protein (CP), crude fat (CF), calcium (Ca) and phosphorus (P)). Dietary phytase and carbohydrases supplementation improved significantly overall ileal amino acid digestibilities of SBM, RSM and CSM based diets (p<0.05). The simultaneous inclusion of phytase and carbohydrases in both of CSD and CD reduced feed cost per kg body weight gain (FCG). Also, results suggest that 2.5 to 3% of RSM and CSM, respectively, might be used as a protein source in growing pig diets without having an adverse effect on the growth performance and nutrient digestibility and simultaneous phytase and carbohydrases addition improves nutritional value of SBM, RSM and CSM by improving ileal amino acid digestibilities.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.9
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• pp.1477-1486
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• 2020

Objective: The objective of this study was to evaluate the effect of different levels of lycopene supplementation on the carcass traits, meat quality, concentration of lipid oxidation products and antioxidant potential in the meat and liver of finishing barrows and gilts. Methods: A total of 40 barrows and 40 gilts were allotted in a completely randomized block design, arranged in a 2×5 factorial scheme, consisting of two sexes (barrows and gilts) and five dietary levels of lycopene (0, 12.5, 25.0, 37.5, and 50.0 mg/kg). In addition, four storage times (0, 24, 48, and 72 h), at 4℃, were added to the model to evaluate the longissimus lumborum muscle. Results: An interaction (p = 0.010) was observed between storage periods and dietary lycopene levels. The unfolding of the interaction (lycopene×period) showed a decreasing concentration of malondialdehyde concentration as the dietary lycopene increased, at all storage periods. No interactions (p>0.050) were observed for the 2,2 diphenyl 1 picrylhydrazyl (DPPH) in the pork. However, the percentage of DPPH radical inhibition reduced (p = 0.001) up to 72 h. Additionally, there was a linear increase (p = 0.001) in the capture of DPPH radicals by antioxidants, as the dietary lycopene increased. No interactions were observed (p>0.05) between the evaluated factors in liver. However, lipid oxidation was reduced by supplementing lycopene in pig diets. The capture of the DPPH radical, resulted increase in the antioxidant power exerted by lycopene in the liver (p = 0.001). The concentrations of the thiobarbituric acid reactive substances and DPPH in the liver were affected by sex (p = 0.001). Conclusion: Dietary supplementation of lycopene reduced the water loss during thawing and was effective in protecting against oxidation of the longissimus lumborum muscle and liver until 72 hours of storage, and the best results were obtained by supplementing with 50.0 mg of lycopene/kg of diet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.711-719
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• 2016

In this study, we derived an theoretical equation, using a simplified spring-mass model for the rolling stock, to obtain the overriding behavior of a leading vehicle, which is considered as the main factor in train accidents. To verify the derived equation, we created a simple 2D model based on the theoretical model, and a simple 3D model considering the characteristics of the power bogie. We then compared the theoretical results with the simulation results obtained using LS-DYNA. The maximum relative derivations in the vertical displacements at the first end-buffer, which is the most important point in overriding, were 3.5 [%] and 1.7 [%] between the two results. Further, we evaluated collision-induced overriding displacements using the theoretical equation for a rubber draft gear, a hydraulic buffer under various collision conditions. We have suggested a theoretical approach for the realization of overriding collision accidents or the energy absorption design of the front end of trains.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.979-986
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• 2016

The tripod shafts of constant-velocity joint are used in both the trains KTX and KTX-sanchon. It is an important component that connects the motor reduction unit and the axle reduction unit in a power bogie. The tripod shaft not only transmits drive and brake torque in the rotational direction, but also slides in the axial direction. If the drive system is loaded with an excessive torque, the fuse part of the shaft will be fractured firstly to protect the other important components. In this study, a rig was developed for conducting torsion tests on the tripod shaft, which is a type of mechanical fuse. The tripod shafts were subjected to torsional fracture test and torsional fatigue test on the rig. The weak zone of the tripod shaft was identified, and its fatigue life was predicted using finite element analysis (FEA). After analyzing the FEA results, design solutions were proposed to improve the strength and fatigue life of the tripod shaft. Furthermore, the deterioration trend and time for failure of the tripod shaft were verified using the hysteresis loops which had been changed with the advancement of the torsional fatigue test.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.501-513
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• 2020

Cutter cutting tests for the cutter placement in the cutter head are being conducted through various studies. Although the cutter spacing at the minimum specific energy is mainly reflected in the cutter head design, since the optimum cutter spacing at the same cutter penetration depth varies depending on the rock conditions, studies on deciding the optimum cutter spacing should be actively conducted. The machine learning techniques such as the decision tree-based regression model and the SVM regression model were applied to predict the optimum cutter spacing ratio for the nonlinear relationship between cutter penetration depth and cutter spacing. Since the decision tree-based methods are greatly influenced by the number of data, SVM regression predicted optimum cutter spacing ratio according to the penetration depth more accurately and it is judged that the SVM regression will be effectively used to decide the cutter spacing when designing the cutter head if a large amount of data of the optimum cutter spacing ratio according to the penetration depth is accumulated.