• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.43-50
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• 2008

Various studies are being conducted to achieve efficient routing and reduce energy consumption in wireless sensor networks where energy replacement is difficult. Among routing mechanisms, the clustering technique has been known to be most efficient. The clustering technique consists of the elements of cluster construction and data transmission. The elements that construct a cluster are repeated in regular intervals in order to equalize energy consumption among sensor nodes in the cluster. The algorithms for selecting a cluster head node and arranging cluster member nodes optimized for the cluster head node are complex and requires high energy consumption. Furthermore, energy consumption for the data transmission elements is proportional to $d^2$ and $d^4$ around the crossover region. This paper proposes a means of reducing energy consumption by increasing the efficiency of the cluster construction elements that are regularly repeated in the cluster technique. The proposed approach maintains the number of sensor nodes in a cluster at a constant level by equally partitioning the region where nodes with density considerations will be allocated in cluster construction, and reduces energy consumption by selecting head nodes near the center of the cluster. It was confirmed through simulation experiments that the proposed approach consumes less energy than the LEACH algorithm.

• Journal of Life Science
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• v.28 no.5
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• pp.587-596
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• 2018

This study aims to observe changes in heart-rate variability (HRV) indices induced by e-cigarette and conventional-cigarette smoking and to compare the differences in acute cardiac autonomic regulation. All participants (n=41) were exposed to both e-cigarette smoke (ES) and conventional cigarette smoke (CS) in a randomized crossover trial. HRV analysis was performed during each smoking session based on a recorded r-r interval 10 minutes before smoking and at specified recovery periods (REC1, 0-5 min; REC2, 5-10 min; REC3, 10-15 min; REC4, 15-20 min; REC5, 20-25 min; and REC6, 25-30 min). ES led to a significantly increased cardiac sympathetic index (LF/HF ratio) compared with the baseline, and it shifted the sympathovagal balance toward sympathetic predominance, including reduction in the complexity of the interbeat interval (SampEn). In REC1 after ES, only decreases of parasympathetic indices such as rMSSD, pNN50, HF, and SD1 were indicated. CS sessions produced not only an increased LF/HF ratio during smoking and recovery periods (REC1 and REC4) but also enhanced sympathetic predominance on autonomic balance during smoking and recovery periods (REC1, REC2, and REC4). In the CS trials, parasympathetic indices of time and non-linear analysis (rMSSD, pNN50, and SD1) were decreased during smoking and in REC1 to REC5. SampEn was also reduced during smoking and REC1 to REC4. Acute sympathoexcitatory effects induced by e-cigarette use produced statistically significant results. Parasympathetic withdrawal after smoking suggests that e-cigarettes may cause increased cardiovascular risk.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.107-114
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• 2017

The performance of polymer electrolyte membrane fuel cell (PEMFC) could be deteriorated when fuel contains contaminants such as carbon monoxide (CO) or hydrogen sulfide ($H_2S$). Generally, $H_2S$ is introduced in hydrogen by steam reforming of hydrocarbon which has mercaptan as odorant. $H_2S$ poisoning effect on PEMFC performance was examined on this study. Pure hydrogen injection, voltage cycling and water circulation methods were compared as performance recovery methods. The PEMFC performance was analyzed using electrochemical methods such as polarization curve, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Pure hydrogen injection and voltage cycling methods showed low recovery ratio, however, water circulation method showed high recovery ratio over 95%. Because anode was directly poisoned by $H_2S$, anode water circulation showed higher recovery ratio compared to the other methods. Water circulation method was developed to recover PEMFC performance from $H_2S$ poisoning. This method could contribute to PEMFC durability and commercialization.

• Journal of Music and Human Behavior
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• v.9 no.2
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• pp.53-67
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• 2012

Improvisational music therapy is known to promote social engagement in children with autism. This study investigated salient features that characterize the engagement of the child with autism and the therapist in improvisational music therapy. Through video analysis of the children's behavior, this study sets out to investigate what engages children with autism into mutual play with the therapist in improvisational music therapy by measuring the shared musical elements between the child and the therapist during musical synchronicity episodes and the children's choice of instruments. A repeated measures, a crossover design was employed in two different conditions (n = 10). Children were randomly assigned into two groups; group 1 participated music therapy first, followed by play therapy second. Group 2 followed the reverse order. Specific target behaviors were analyzed in the selected sessions 1, 4, 8 and 12. As expected, improvisational music therapy produced markedly more and longer events of musical synchronicity in children with autism than the play sessions with toys (p < .001). Rhythm and dynamic appeared to be the two most salient elements during musical synchronicity events between the child and the therapist. Observational findings confirmed that horns and whistles were the most frequently selected instruments in music therapy, whereas a dollhouse set was in play therapy by children with autism. The clinical implications and the details of these findings are discussed further.

• Journal of Pharmaceutical Investigation
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• v.34 no.3
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• pp.209-214
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• 2004

A bioequivalence study of $Roxithrin^{TM}$ tablet (Kukje Pharma. Ind. Co., Ltd.) to $Rulid^{TM}$ tablet (Han Dok Pharma. Ind. Co., Ltd.) was conducted according to the guidelines of Korea Food and Drug Administration (KFDA). Twenty four healthy male Korean volunteers received each medicine at the roxithromycin dose of 300 mg in a $2{\times}2$ crossover study. There was a one-week wash-out period between the doses. Plasma concentrations of roxithromycin were monitored by a high-performance liquid chromatography for over a period of 36 hours after drug administration. $AUC_t$ (the area under the plasma concentration-time curve from time zero to 36 hr) was calculated by the linear trapezoidal rule method. $C_{max}$ (maximum plasma drug concentration) and $T_{max}$ (time to reach $C_{max}$) were compiled from the plasma concentration-time data. Analysis of variance was carried out using logarithmically transformed $AUC_t$ and $C_{max}$. No significant sequence effect was found for all of the bioavailability parameters indicating that the cross-over design was properly performed. The 90% confidence intervals of the $AUC_t$ ratio and the $C_{max}$ ratio for $Roxithrin^{TM}/Rulid^{TM}$ were 1.00 - 1.13 and 0.98 - 1.10, respectively. These values were within the acceptable bioequivalence intervals of 0.80 - 1.25. Thus, our study demonstrated the bioequivalence of $Roxithrin^{TM}$ and $Rulid^{TM}$ with respect to the rate and extent of absorption.

• Journal of Pharmaceutical Investigation
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• v.38 no.6
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• pp.421-427
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• 2008

The purpose of the present study was to evaluate the bioequivalence of two etodolac capsules, Kuhnillodin capsule (Kuhnil. Co., Ltd., Seoul, Korea) as reference drug and Etodin capsule (Myungmun Pharm. Co., Ltd., Seoul, Korea) as test drug, according to the guidelines of Korea Food and Drug Administration (KFDA). Twenty-three healthy male Korean volunteers received one capsule at the dose of 200 mg etodolac in a $2{\times}2$ crossover study. There was a one-week washout period between the doses. Plasma concentrations of etodolac were monitored by a high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) for over a period of 24 hr after the administration. $AUC_{0-24\;hr}$ was calculated by the linear trapezoidal rule method. $C_{max}$ and $T_{max}$ were compiled from the plasma concentration-time data. Analysis of variance (ANOVA) was carried out using logarithmically transformed $AUC_{0-24\;hr}$ and $C_{max}$. The 90% confidence intervals of the $AUC_{0-24\;hr}$ ratio and the $C_{max}$ ratio for Etodin/Kuhnillodin were $\log\;0.97{\sim}\log\;1.08$ and $\log\;0.89{\sim}\log\;1.19$, respectively. These values were within the acceptable bioequivalence intervals of $\log\;0.80{\sim}\log\;1.25$. Thus, our study demonstrated that Etodin was bioeqiovalent to Kuhnillodin preparation when the rate and extent of absorption between two preparations were compared.

• Korean Journal of Clinical Pharmacy
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• v.8 no.2
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• pp.95-100
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• 1998

Piroxicam-$\beta$-cyclodextrin은 piroxicam을 $\beta$-cyclodextrin으로 포접시킨 비스테로이드성 항염증약물이다. 이러한 포접형 약물은 위장관에서의 흡수속도가 증가하는 것으로 외국자료에서 보고되고 있으며 이는 이 약물의 위장관 내성에 보다 나은 영향을 끼칠 수 있음을 시사하고 있다. 본 연구는 정상성인 한국인을 대상으로 randomized, crossover design에 의해 piroxicam-$\beta-cyclodextrin(Brexin^{(R)})$과 piroxicam 확산정$(Feldene^{(R)})$ 흡수속도를 비교하고자 하였다. 건강한 성인 8명의 피험자를 2군으로 나누어 시험약 또는 대조약을 각각 20 mg씩 20일의 휴약 기간을 두고 이중 맹검으로 교차 투여하였다. 시험약 또는 대조약의 투여 후 24시간 동안 일정 간격으로 채혈하여 HPLC 방법으로 혈장 내 piroxicam 농도를 측정하였다. $AUC_{0-24}\;({\mu}g/mL)$는 piroxicam-$\beta$-cyclodextrin군에서 $56.1\pm4.9$, piroxicam군에서 $57.3\pm5.6$으로 통계적인 유의성이 없었으나, 투여 후 0.5시간에서의 혈중농도는 piroxicam-$\beta$-cyclodextrin군 $2.9\pm0.4\;{\mu}g/mL$, piroxicam군 $1.6\pm0.3\;{\mu}g/mL$으로 통계적인 유의성을 보였다(p<0.05). 또한 최고혈중농도는 piroxicam-$\beta$-cyclodextrin$(4.3\pm0.5\;{\mu} g/mL)\;piroxicam(3.5\pm0.3\l{\mu}g/mL)$,으로 유의성이 있었으며(p<0.05), 흡수 속도상수는 piroxicam-$\beta$-cyclodextrin$(3.00\pm0.49\;h^{-1}), \;piroxicam(1.80\pm0.21\;h^{-1})$이었다(p<0.1). 이상의 결과에서, piroxicam-$\beta$-cyclodextrin정은 piroxicam 확산정과 비교하여 흡수되는 정도는 서로 비슷하지만 흡수 초기의 혈장농도 및 흡수속도상수에서 보다 빠른 약동학적 특성을 나타내었다.

• Korean Journal of Clinical Pharmacy
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• v.8 no.2
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• pp.107-112
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• 1998

Lovastatin is a lipid lowering agent for the treatment of hypercholesterolemia and belongs to a new class of pharmacologic compounds called the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors. By competitively inhibiting HMG CoA reductase, lovastatin disrupts the biosynthesis of cholesterol in hepatic and peripheral cells and increases the synthesis of high-density-lipoprotein HDL) receptors. Following oral administration, the lactone ring of lovastatin is hydrolysed to the active inhibitor of HMG CoA reductase, lovastatin acid. Lovastatin is known to have poor oral absorption and wide individual variation. In this study, bioequivalence test of two lovastatin formulations, the test drug ($Lovaload^{TM}$, Chong Kun Dang Pharmaceutical Co.) and the reference drug ($Mevacor^{TM}$, Chung Wae Pharmaceutical Co.) were conducted according to the guidelines of Korea Food and Drug Administration (KFDA). A total of 18 healthy male volunteers, $31.90\pm3.60$ years old and $72.17\;7.88$ kg of body weight in average, were evaluated in a randomized crossover manner with a 2-week washout period. Concentrations of lovastatin acid in plasma were measured upto 12 hours following a single oral administration of eight tablets (20 mg of lovastatin per tablet) by high-performance liquid chromatography with UV detection at 238 nm. The area under the concentration-vs-time curve from 0 to 12 hours $(AUC_{0-12h})$ was calculated by the trapezoidal summation method. The statistical analysis showed that there are no significant differences in $AUC_{0-12h),\;C_{max}\;and\;T_{max}$ between the two formulations ($6.72\%,\;1.52\%,\;and\;0.88\$, respectively). The least significant differences between the formulations at $\alpha$=0.05 were less than $20\%\;(11.65\%,\;19.73\%,\;and\;14.81\%\;for\;AUC_{0-12h},\;C_{max}\;and\;T_{max}$, respectively). The $90\%$ confidence intervals for these parameters were also within $\pm20\%\;(-1.50{\leq}{\delta}{\leq}15.00$, $-12.50{\leq}{\delta}{\leq}15.50,\;and\;-9.64{\leq}{\delta]{\leq}11.40{\leq}\;for\;\;AUC_{0-12h}$ ,$C_{max}\;and\;T_{max}$, respectively). In conclusion, the new generic product $Lovaload^{TM}$ was proven to be bioequivalent with the reference drug.

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.89-94
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• 2006

Nafion/poly(ether(amino sulfone)) acid-base blend polymer electrolyte membranes were prepared and their proton conductivity and dimethyl ether permeability were investigated. Characteristics of direct dimethyl ether fuel cell (DDMEFC) performance using prepared blend membrane were studied. The increase of amine groups in the base polymer in composite membranes resulted in the decrease in dimethyl ether permeability. The proton conductivity of the blend membranes gradually increased as increasing temperature. The conductivity of Nafion/PEAS-0.6 (85:15) blend membranes was measured to be $1.42\times10^{-2}S/cm\;at\;120^{\circ}C$ which was higher than that of the recast Nafion. The performance of direct dimethyl ether fuel cell (DDMEFC) using the Nafion/PEAS blend membranes was higher than that using $Nafion^(R)115$ membrane. Enhanced performance of direct dimethyl ether fuel cells using Nafion/PEAS blend membrane was explained by reducing dimethyl ether (DME) crossover through the electrolyte membrane and maintenance of the proton conductivity at high temperature.

• Tuberculosis and Respiratory Diseases
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• v.78 no.4
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• pp.326-335
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• 2015

Background: Asian dust is known to have harmful effects on the respiratory system. Respiratory conditions are also influenced by environmental conditions regardless of the presence of pollutants. The same pollutant can have different effects on the airway when the air is dry compared with when it is humid. We investigated hospital visits for chronic obstructive pulmonary disease (COPD) and asthma in relation to the environmental conditions. Methods: We conducted a retrospective study using the Korean National Health Insurance Service claims database of patients who visited hospitals in Chuncheon between January 2006 and April 2012. Asian dust, haze, mist, and fog days were determined using reports from the Korea Meteorological Administration. Hospital visits for asthma or COPD on the index days were compared with the comparison days. We used two-way case-crossover techniques with one to two matching. Results: The mean hospital visits for asthma and COPD were $59.37{\pm}34.01$ and $10.04{\pm}6.18$ per day, respectively. Hospital visits for asthma significantly increased at lag0 and lag1 for Asian dust (relative risk [RR], 1.10; 95% confidence interval [CI], 1.01-1.19; p<0.05) and haze (RR, 1.13; 95% CI, 1.06-1.22; p<0.05), but were significantly lower on misty (RR, 0.89; 95% CI, 0.80-0.99; p<0.05) and foggy (RR, 0.89; 95% CI, 0.84-0.93; p<0.05) days than on control days. The hospital visits for COPD also significantly increased on days with Asian dust (RR, 1.29; 95% CI, 1.05-1.59; p<0.05), and were significantly lower at lag4 for foggy days, compared with days without fog (RR, 0.85; 95% CI, 0.75-0.97; p<0.05). Conclusion: Asian dust showed an association with airway diseases and had effects for several days after the exposure. In contrast to Asian dust, mist and fog, which occur in humid air conditions, showed the opposite effects on airway diseases, after adjusting to the pollutants. It would require more research to investigate the effects of various air conditions on airway diseases.