• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.5
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• pp.555-560
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• 2014

In order to improve spectrum sensitivity of photodiode for detection of the laser wavelength at 850 nm ~ 1000 nm of near-infrared band, this study has produced silicon-based photodiode whose area is $5000{\mu}m{\times}2000{\mu}m$, and the thickness is $280{\mu}m$. It was packed by the TO-5 type. The electrical properties of the dark currents have valued of approximately 0.1 nA for 5 V reverse bias, while the capacitance showed 32.5 pF at frequency range of 1 kHz and about 32.4 pF at the range of 200 kHz for 0 V. In addition, the rising time of output signal was as fast response as 20.92 ns for 10V. For the optical properties, the best spectrum sensitivity was 0.57 A/W for 890 nm, while it was relatively excellent value of 0.37 A/W for 1,000 nm. Over all, there were good spectrum sensitivity for this diode over the range of 870 ~ 920 nm.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.44-54
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• 2000

In this paper, a design methodology for the frequency-adaptive negative-delay circuit which can be implemented in standard CMOS memory process is proposed. The proposed negative-delay circuit which is a basic type of the analog SMD (synchronous mirror delay) measures the time difference between the input clock period and the target negative delay by utilizing analog behavior and repeats it in the next coming cycle. A new technology that compensates the auxiliary delay related with the output clock in the measure stage differentiates the Proposed method from the conventional method that compensates it in the delay-model stage which comes before the measure stage. A wider negative-delay range especially prominent in the high frequency performance than that in the conventional method can be realized through the proposed technology. In order to implement the wide locking range, a new frequency detector and the method for optimizing the bias condition of the analog circuit are suggested. An application example to the clocking circuits of a DDR SDRAM is simulated and demonstrated in a 0.6 ${\mu}{\textrm}{m}$ n-well double-poly double-metal CMOS technology.

• Progress in Superconductivity
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• v.14 no.2
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• pp.92-95
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• 2012

Superconducting detectors are promising as ion detectors for time-of-flight mass spectrometers (TOF MS). They can achieve mass-independent detection efficiency even for macromolecular bombardments, because output signals are produced through the deposited kinetic energy at ion impact instead of secondary electron emission that is the ion detection mechanism of conventional microchannel plate (MCP) detectors or secondary electron multipliers (SEM). Among the superconducting detectors, the superconducting strip ion detectors (SSIDs), which consist of several hundreds of superconducting lines with a width of a few hundreds nm and a thickness of a few tens of nm, have a fast response time of less than 1 ns. Inherently, the response time of SSIDs is determined by kinetic inductance, so that it was difficult to realize a fast SSID with a large detection area. However, we succeeded in realizing the detector size up to $5{\times}5mm^2$ without response time degradation by using a parallel configuration.

• Journal of Pharmaceutical Investigation
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• v.38 no.5
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• pp.343-348
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• 2008

The bioequivalence of two cyclosporine A (CyA) 100 mg soft capsules (Chong Kun Dang's $Cipol-N^{(R)}$ as the test drug; Korea Novartis' Sandimmun $Neoral^{(R)}$ as the reference drug) was assessed in healthy male Korean volunteers after oral administration of 200 mg CyA according to a randomized crossover design. The whole blood samples were analyzed for the determination of parent CyA in the blood by using a validated HPLC/diode array detector method. The mean $AUC_t$ values for reference and test products were $4095.3{\pm}1397.2$ and $3958.3{\pm}1138.2\;ng{\cdot}hr/mL$, respectively. The mean $C_{max}$ values were $1135.9{\pm}293.2\;ng/mL$ for the reference product, and $985.0{\pm}207.9\;ng/mL$ for the test product. $T_{max}$ was $1.6{\pm}0.4\;hr$ for the reference and $1.8{\pm}0.5\;hr$ for the test product. The differences of $AUC_t$, $C_{max}$ and $T_{max}$ were -3.35, -13.28 and +10.63%, respectively. The point estimates and 90% confidence intervals for $AUC_t$ and $C_{max}$ were 0.981 (0.9171 to 1.0514) and 0.876 (0.8229 to 0.9336), respectively. Based on the pharmacokinetic and statistical data, we conclude that these two products are bioequivalent and can be considered interchangeable in the medical practice.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.1
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• pp.56-63
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• 2008

This paper describes a 12 bit 1GS/s current mode segmented DAC for WCDMA communication. The proposed circuit in this paper employes segmented structure which consists of 4bit binary weighted structure in the LSB and 4bit thermometer decoder structure in the mSB and MSB. The proposed DAC uses delay time compensation circuits in order to suppress performance decline by delay time in segmented structure. The delay time compensation circuit comprises of phase frequency detector, charge pump, and control circuits, so that suppress delay time by binary weighted structure and thermometer decoder structure. The proposed DAC uses CMOS $0.18{\mu}m$ 1-poly 6-metal n-well process, and measured INL/DNL are below ${\pm}0.93LSB/{\pm}0.62LSB$. SFDR is approximately 60dB and SNDR is 51dB at 1MHz input frequency. Single DAC's power consumption is 46.2mW.

• Progress in Medical Physics
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• v.8 no.1
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• pp.3-15
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• 1997

Adrenal chromaffin cells secrete catecholamine in response to acetylcholine. The secretory response has absolute requirement for extracellular calcium, indication that $Ca^{2+}$ influx through voltage dependent $Ca^{2+}$ channel (VDCC) is the primary trigger of the secretion cascade. Although the existence of various types of $Ca^{2+}$ channels has been explored using patch clamp technique in adrenal chromaffin cells, the contribution of different types of $Ca^{2+}$ channels to catecholamine secretion remains to be established. To investigate the quantative contribution of different types of $Ca^{2+}$ channels to cate-cholamine secretion, $Ca^{2+}$ current($I_{Ca}$) and the resultant membrane capacitance increment($\Delta{C}_{m}$) were simultaneoulsy measured. Software based phasor detector technique was used to monitor $\Delta{C}_{m}$. After blockade of L type VDCC with nicardipine (1$\mu$M), $I_{ca}$ was blocked to 43.85$\pm$6.72%(mean$\pm$SEM) of control and the resultant ㅿC$_{m}$ was reduced ot 30.10$\pm$16.44% of control. In the presence of nicardipine and $\omega$-conotoxin in GVIA(l$\mu$M), an N type VDCC antagonist, $I_{ca}$ was blocked to 11.62$\pm$2.96% of control and the resultant $\Delta{C}_{m}$ was reduced to 26.13$\pm$8.25% of control. Finally, in the presence of L, N, and P type $Ca^{2\pm}$ channel antagonists(nicardipine, $\omega$-Conotoxin GVIA, and $\omega$-agatoxin IVA, respectively), $I_{ca}$ and resultant $\Delta{C}_{m}$ were almost completely blocked. From the observation of parallel effects of $Ca^{2+}$ channel antagonists on $I_{ca}$ and $\Delta{C}_{m}$, it was concluded that L, N, and also P type $Ca^{2+}$ channels served and $Ca^{2+}$ source for exocytosis and no difference was observed in their efficiency to evoke exocytosis amost L, N, and P type $Ca^{2+}$ channels.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.9
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• pp.58-67
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• 2009

This paper presents a fully digital gain control system with a new high bandwidth and wide dynamic range power detector for DVB-S2 application. Because the peak-to-average power ratio (PAPR) of DVB-S2 system is so high and the settling time requirement is so stringent, the conventional closed-loop analog gain control scheme cannot be used. The digital gain control is necessary for the robust gain control and the direct digital interface with the baseband modem. Also, it has several advantages over the analog gain control in terms of the settling time and insensitivity to the process, voltage and temperature variation. In order to have a wide gain range with fine step resolution, a new AGC system is proposed. The system is composed of high-bandwidth digital VGAs, wide dynamic range power detectors with RMS detector, low power SAR type ADC, and a digital gain controller. To reduce the power consumption and chip area, only one SAR type ADC is used, and its input is time-interleaved based on four power detectors. Simulation and measurement results show that the new AGC system converges with gain error less than 0.25 dB to the desired level within $10{\mu}s$. It is implemented in a $0.18{\mu}m$ CMOS process. The measurement results of the proposed IF AGC system exhibit 80-dB gain range with 0.25-dB resolution, 8 nV/$\sqrt{Hz}$ input referred noise, and 5-dBm $IIP_3$ at 60-mW power consumption. The power detector shows the 35dB dynamic range for 100 MHz input.

• Progress in Medical Physics
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• v.6 no.2
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• pp.71-81
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• 1995

Consecutive brain 〔Tc-99m〕ECD SPECT studies before and after acetazolamide (Diamox) administration have been performed with patients for the evaluation of cerebrovascular hemodynamic reserve. However, the quantitaitve potential of SPECT Diamox imaging is limited as a result of degrading fractors such as finite detector resolution, attenuation, scatter, poor counting statistics, and methods of data analysis. Making physical measurements in phantoms filled with known amounts of radioactivity can help characterize and potentially quantify the sensitivities. However, it is often very difficult to make a realistic phantom simulating patients in clinical situations. By computer simulation, we studied the sensitivities of ECD SPECT before and after Diamox administration. The sensitivity is defined as ($\Delta$N/N)/($\Delta$S/S)$\times$100％, where $\Delta$N denotes the differences in mean counts between post-and pre-Diamox in the measured data, N denotes the mean counts before Diamox in the measure data, $\Delta$S denotes the differences in mean counts between post-and pre-Diamox in the model, and S denotes the mean counts before Diamox in the model. In clinical Diamox studies, the percentage changes of radioactivity could be determined to measure changes in radioactivity concentration by Diamox after subtracting pre-from post-Diamox data. However, the optimal amount of subtraction for 100％ sensitivity is not known since this requires a thorough sensitivity analysis by computer simulation. For consecutive brain SPECT imaging model before and after Diamox, when 30％ increased radioactivity concentrations were assingned for Diamox effect in model, the sensitivities were measured as 51.03, 73.4, 94.00, 130.74％ for 0, 100, 150, 200％ subtraction, respectively. Sensitivity analysis indicated that the partial voluming effects due to finite detector resolution and statistical noise result in a significant underestimation of radioactivity measurements and the amount of underestimation depends on the. ％ increase of radioactivity concentration and ％ subtraction of pre-from post-Diamox data. The 150％ subtraction appears to be optimal in clinical situations where we expect approximately 30％ changes in radioactivity concentration. The computer simulation may be a powerful technique to study sensitivities of ECD SPECT before and after Diamox administration.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1028-1032
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• 2003

To assess accurate methods for measuring sulfur dioxide residue in pickles, the acid distillation HPLC-UV method and Monnier Willams modified method were examined. By the acid distillation HPLC-UV method, sulfites released from pickles by acid distillation were absorbed in 1% triethanolamine solution and detected as sulfite ion by HPLC with UV monitoring at 240nm. An anion exchange column was employed with 1.8mM $Ma_2CO_3-1.7mM\;NaHCO_3$ solution as a mobile phase, $84.0{\sim}91.7%$ of sulfite added to pickled radish were recovered. Total sulfite levels from 48 kinds of pickles analyzed by acid distillation HPLC-UV was compared with those analyzed by the Monnier Williams modified method. The Monnier Williams modified method showed higher levels of sulfur dioxide than the acid distillation HPLC-UV method due to the presence of volatile acids in pickles. The concentration of sulfur dioxide was in the range of $N.D{\sim}173.05ppm$ in pickled radish and over 30ppm of sulfur dioxide from 3 samples by the acid distillation-HPLC-UV method.

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.276-282
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• 2014

An accurate and sensitive analytical method was established for the simultaneous determination of synephrine and n-methyltyramine contents by ultra-performance liquid chromatography (UPLC) with a fluorescence detector (FLD). A 70:30 (v/v) mixture of 10 mM sodium dodecyl sulfate (SDS) and acetonitrile was used as the mobile phase. The coefficient of correlation ($r^2$) was 0.9999 for both synephrine and n-methyltyramine, and their limits of detection (LOD) were 0.02 and 0.01 mg/kg, respectively. The percentage recoveries for synephrine and n-methyltyramine were 96.4% and 100.9%, respectively, from bitter orange (Citrus aurantium) samples. The synephrine and n-methyltyramine contents were 38.07-118.21 mg/kg and 0.27-0.56 mg/kg, respectively, in the orange fruit samples, while they were 14.61-120.39 mg/kg and up to 3.34 mg/kg, respectively, in the tested commercial orange juice samples. The differences in synephrine and n-methyltyramine content between orange fruit and commercial orange juice were not significant (p<0.05). These results suggest that UPLC-FLD can be applied to develop an analytical method of quality control for commercial orange juice.