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There are no effective treatments for relieving neuronal dysfunction after mild traumatic brain injury (TBI). Here, we evaluated therapeutic efficacy of human embryonic stem cell-derived cerebral organoids (hCOs) in a mild TBI model, in terms of repair of damaged cortical regions, neurogenesis, and improved cognitive function.Male C57BL/6 J mice were randomly divided into sham-operated, mild TBI, and mild TBI with hCO groups. hCOs cultured at 8 weeks were used for transplantation. Mice were sacrificed at 7 and 14 days after transplantation followed by immunofluorescence staining, cytokine profile microarray, and novel object recognition test.8W-hCOs transplantation significantly reduced neuronal cell death, recovered microvessel density, and promoted neurogenesis in the ipsilateral subventricular zone and dentate gyrus of hippocampus after mild TBI. In addition, increased angiogenesis into the engrafted hCOs was observed. Microarray results of hCOs revealed neuronal differentiation potential and higher expression of early brain development proteins associated with neurogenesis, angiogenesis and extracellular matrix remodeling. Ultimately, 8W-hCO transplantation resulted in reconstruction of damaged cortex and improvement in cognitive function after mild TBI.hCO transplantation may be feasible for treating mild TBI-related neuronal dysfunction via reconstruction of damaged cortex and neurogenesis in the hippocampus.

BackgroundCopeptin has been reported as a predictive biomarker for the prognosis after traumatic brain injury (TBI). However, most of them were in patients with severe TBI and limited value in predicting outcomes in patients with moderate TBI defined as Glasgow Coma Scale (GCS) score from 9 to 12. We aimed to investigate the predictive value of copeptin in assessing the neurologic outcome following moderate TBI.MethodsPatients were prospectively enrolled between May 2017 and November 2020. We consecutively measured plasma copeptin within 24 h after trauma, days 3, 5, and 7 using ELISA. The primary outcome was to correlate plasma copeptin levels with poor neurologic outcome at 6 months after moderate TBI. The secondary outcome was to compare the prognostic accuracy of copeptin and C-reactive protein (CRP) in assessing the outcome of patient.ResultsA total of 70 patients were included for the final analysis. The results showed that 29 patients (41.4%) experienced a poor neurologic outcome at 6 months. Multivariable logistic regression analysis revealed that increased copeptin (odds ration [OR] = 1.020, 95% CI: 1.005–1.036), GCS score of 9 or 10 (OR = 4.507, 95% CI: 1.266–16.047), and significant abnormal findings on CT (OR = 4.770; 95% CI: 1.133–20.076) were independent risk factors for poor outcomes. Consecutive plasma copeptin levels were significantly different according to outcomes (p < 0.001). Copeptin on day 7 exhibited better prognostic performance than CRP with an area under receiver operating characteristic curve (AUROC) difference of 0.179 (95% CI: 0.032–0.325) in predicting 6-month poor outcomes.ConclusionPlasma copeptin level can be a useful marker in predicting 6-month outcomes in patients with moderate TBI.

Most of systems that supplying electric power to operate an electric train of an urban railway to supply power by converting AC into DC through trolly wire, there are two rectification methods to converting AC into DC, with diodes or thyristor. Rectification method using thyristor is composed by 12 pulse thyristor converter with forward and reverse connection. Forward connection thyristor converter supplies electric power to trolly wire as forward mode operation, Reverse connection thyristor converter returns surplus trolly wire voltage to AC top main when regenerative electric power occurs according to regenerative braking, which reduces 20% operating power of an electric train. Rectification method using thyristor is appropriate for an electric train of an urban railway for improving operation efficiency and reducing greenhouse gases. In this paper, propose a dual converter using thyristor system for an urban railway substations and a control algorithm, and the validity of the proposed control technique is verified by the fabrication and experiment of 10 kW scale reduction model.

A control algorithm of thyristor dual converter power system is proposed in this study for a railway power substation. The thyristor dual converter can use regenerative power without an additional system using control algorithm. An autonomous voltage and mode change method is also proposed to provide uninterrupted power to the railway. A 10 kW reduced model of the thyristor dual converter power system is built and tested to verify the validity of the proposed control algorithm.

In this paper, we propose a clipping method for LDPC coded FH BFSK system over partial-band jamming channel. We apply the erasure insertion technique, which had been studied much earlier, now to LDPC codes and discuss its performance degradation region. By using clipping technique, the performance degradation can be removed. Finally, we discuss the erasure insertion and clipping techniques for various jamming conditions.

In this paper, we propose a non-convex compressed sensing(NCCS)-based channel state information(CSI) feedback scheme for massive multiple-input multiple-output(MIMO) systems. Combining the random vector quantization(RVQ), the proposed scheme permits a transmitter to obtain CSI with acceptable accuracy under substantially reduced feedback load. Furthermore, it recovers CSI from fewer measurements than that of existing convex compressed sensing(CCS)-based schemes even if the measurements are inaccurate and incomplete. Simulation results show that the proposed scheme achieves higher throughput than both existing CCS-based feedback scheme and random vector quantization(RVQ) feedback scheme with the same feedback load.

The electric power required to operate the urban railway supplies DC 1,500 V to the electric train through trolly wire. The rectifier which converts AC to DC has a rectification method using a diode and a rectification method using a thyristor. The thyristor rectification method is easier to adjust the trolly wire voltage than the diode rectification method. In addition, it is possible to reuse the regenerative electric power generated when the electric train stops, thereby helping to reduce the operating cost of the Urban railway operator and to reduce the greenhouse gas. However, the thyristor rectification method has a disadvantage in that the power factor of an urban railway substation is lowered because a harmonic current is generated during rectification and the reactive power becomes large. In this paper, we analyze the harmonic currents generated of Busan Urban railway substation system using thyristor rectifier, we propose an optimal harmonic filter to achieve a power factor of over 90% by simulation.

The internet of things (IoT) requires that more data are collected and processed by devices with faster response, but lower power consumption. In order to achieve these unprecedented requirements, a high-speed DRAM with low-power dissipation at standby and during low-frequency operation in a small footprint is necessary. In addition, a higher degree of reliability is expected for some applications: such as transportation and healthcare. One promising solution, on-chip error correction coding (ECC), has gained traction among memory companies [1] and is now required by the LPDDR4 standard for the first time [2]. In this paper, a 2Gb LPDDR4 that dissipates 75% less refresh current than a conventional LPDDR4 is presented. The proposed LPDDR4 exploits ECC to reduce refresh current, periodically activated voltage regulators to reduce standby power, and dual CA buffers to save the buffer current during low frequency operation. In addition, circuit designs for cell screen of DRAM with on-chip ECC, and for high-speed wafer test for known good die (KGD) - essential for small form factor devices using system-in-package (SiP) - are presented.

In this paper, we propose an iterative detection and decoding scheme for the LDPC coded multiuser uplink massive-MIMO systems. We consider the simple maximal ratio combining (MRC) detector and LDPC decoder. We formulate the soft output of MRC detector and the relation between the extrinsic informations of the detector and decoder. The performance improvement of the proposed iterative detection and decoding scheme is shown by computer simulation. ※ This work was supported by EWRC program of Agency for Defence Development of Korea. First Author : School of Electrical and Electronic Engineering, Yonsei University, js.park09@yonsei.ac.kr, 학생회원 ° Corresponding Author : School of Electrical and Electronic Engineering, Yonsei University, hysong@yonsei.ac.kr, 종신회원 * School of Electrical and Electronic Engineering, Yonsei University, is.kim@yonsei.ac.kr ** Agency for Defence Development hansw79@add.re.kr 논문번호:KICS2014-06-239, Received June 16, 2014; Revised August 18, 2014; Accepted August 21, 2014 I. 서 론 무선 통신 시스템을 통한 전송 데이터 요구량이 크 게 증가하고 있는 가운데, 이에 필요한 전력과 대역폭 이 주요 제한사항이 되고 있다. 이러한 제한 사항 내에 서 통신 속도를 올리기 위해, 최근 많은 수의 안테나를 사용하는 massive multiple-input multiple-output (massive-MIMO) 시스템이 고려되고 있다 . 하지만 이러한 massive-MIMO 시스템은 많은 양 의 계산 복잡도를 필요로 한다 . MIMO 시스템의 간 섭 없는 신호를 검출하기 위한 선형 검출기로는 zero-forcing (ZF) 또는 minimum mean square error (MMSE) 검출기 등이 사용되어 왔다. Small-scale MIMO 시스템에 이러한 고전적 검출기와 터보 부호 를 연접한 수신기가 제안되었다 . 이러한 고전적 검 출기들은 역행렬의 계산이 필요한데, massive-MIMO 논문 / LDPC 부호화된 멀티유저 상향링크 Massive-MIMO 시스템의 반복 검출 및 복호 수신기 529 그림 1. 멀티유저 상향링크 massive-MIMO 시나리오. Fig. 1. Multiuser uplink massive-MIMO scenario. 시스템을 고려할 경우 큰 행렬의 역행렬 계산이 필요 해지며 그에 따라 계산량 또한 매우 증가하게 된다. 이러한 문제를 해결하기 위해 그래프 상에서 낮은 복 잡도를 갖는 신뢰도 전파 (belief propagation, BP) 검 출기가 제안되었다 . 또한 MIMO 시스템에 LDPC 부호를 사용하는 연 구도 진행되었는데, 최적 및 준 최적의 연판정 MIMO 검출기를 사용하는 연구가 발표되었다 . MassiveMIMO 시스템에 대한 결합적 검출 및 복호기에 대한 연구도 진행되었으나 , 해당 논문에서는 점대점 통신 상에서 송/수신단이 같은 수의 안테나를 사용할 경우 를 가정하였다. 또한 massiveMIMO 시스템에 최적 화된 LDPC 부호가 제안되었다 . Massive-MIMO 시스템의 하향 링크에 대한 연구 는 등이 발표 되었다. 본 논문에서는 여러 유저가 동시에 기지국에 접속하는 상향링크 시스템을 고려한 다. 모바일 기기들은 그 크기가 작아 많은 수의 안테 나를 설치하기 어렵지만, 기지국의 경우는 많은 안테 나를 설치할 수 있고 그에 따른 다이버시티 이득을 취 할 수 있다. 이러한 시나리오에 대해서는 낮은 복잡도 의 간단한 maximal ratio combining (MRC) 검출기가 효과적으로 동작할 수 있다. 본 논문은 이러한 MRC 검출기의 연판정 기법 을 바탕으로 멀티유저 상향링 크 massive-MIMO 시스템의 반복적 MRC 검출 및 LDPC 복호 기법을 제안한다. II장에서는 고려하는 massive-MIMO 시스템과 MRC 검출기, LDPC 복호기를 설명한다. III장에서는 제안하는 반복적 검출 및 복호 과정을 설명한다. IV장 과 V장에서 시뮬레이션 결과와 결론을 통해 논문을 마무리 한다.

This study investigated the daily changes of individual numbers of the baikal teal migrating in Geumgang River from November in 2008 to March in 2009 and from November, 2011 to February, 2012. The finding from 2008 to 2009 showed that the highest number of 500,000 individuals (November, 2008) with an average of 146,582 ± 123,705 individuals were recorded. The finding from 2011 to 2012 indicated that the highest number of 250,000 individuals (January, 2012) with an average of 61,696 ± 63,407 individuals. The baikal teal's population was increased in the early wintering period was not observed in the mid-wintering period when the Geumgang River became frozen. On the other hand, the population tended to increase again in the late wintering period when the river began to thaw. As the baikal teals prefer flat water areas without currents, they were mainly observed in the upper stream of Geumgang estuary barrage but not in the downstream.

In this paper, we have proposed a wide band antenna for manpack SDR(Software Defined Radio). The proposed antenna consists of feeding post, flexible gooseneck and two radiating elements composed of a upper and lower radiators. The upper radiator has a longer electrical length than the lower radiator in order to operate in the lower frequency. Also, the resonant frequency and impedance characteristics of the antenna can be adjusted independently for two radiators. Therefore, the proposed antenna can be achieved wide impedance bandwidth by the combination of two independent resonance modes. To analyze the characteristics of the antenna in the design process is employed the equivalent circuit theory and EM(Electro-Magnetic) simulation. The measurement results show that the proposed antenna have the sufficient wide bandwidth, above -3.4dBi of the gain and fairly good radiation pattern over the wide bandwidth.Key Words : SDR(Software Defined Radio), Wide Band Antenna(광대역 안테나), the Synthesis of Dual Resonance Modes(이중 공진 모드 합성)

This paper proposes a thyrister rectification type of double converter rectification equipment to simplify trolley line equipment and return the regenerative power into AC motion without storage equipment by converting the double converter into Converter(Forward) or Inverter(Reverse) based on voltages supplied for the trolley lines using high current thyristers and keeping voltages supplied for the trolley lines constant and an optimal thyrister firing angle to improve output characteristics in mode conversion of Converter(Forward) or Inverter(Reverse) by the simulation and experiments for operation and output characteristics of the double converter rectification equipment.

Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper presents the simulation of welding-induced residual stress analysis to examine the cause of cracking in the SUS-overlay welding specimen at FPSO Moon Pool structure.

Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper presents the simulation of welding-induced residual stress analysis to examine the cause of cracking in the SUS-overlay welding specimen at FPSO Moon Pool structure.

In this paper, we studied the frequency hopping(FH) performance on the FH radio communication system via M&S of initial synchronization architecture. It is difficult to test the synchronization performance on the real FH communication environment. Thus, we have modeled the synchronization system similar to the real radio communication structure, and simulated the optimum correlation value and the synchronization performance on AWGN channel. As the result, we could obtain the thresholds of correlation synchronization and the FH synchronization performance under the low SNR.

This study was conducted to clarify the community characteristics of birds in Goseong-gun, Gangwon-do, Korea at June and September of 2010. The result observed a total of 6,557 birds of 98 species. Dominant species included, in decreasing order, Larus crassirostris 3,319 counts (50.62%), Passer montanus 664 counts (10.13%), Sterna hirundo 208 counts (3.17%), Paradoxornis webbianus and Egretta alba modesta 178 counts (2.71%). In terms of the families, the herons showed a total of 7 species at 303 counts, the ducks showed 4 species of 185 counts, the raptors showed 6 species of 26 counts, the waders showed 13 species of 114 counts, the gulls showed 8 species of 3,585 counts, the passerine birds showed 56 species of 2,323 counts and others (Grebe, Cormorant, Pheasant, Moorhen) showed only 4 species of 26 counts. In terms of the number of species’ habitat usage, the forest area showed the highest level of species at 52 species, and human inhabited areas showed the lowest level at 14 species.

Background A study was performed on the accidental chlorine gas leakage that occurred in a factory of printed circuit boards manufactured without chlorine. Health examination was performed for all 52 workers suspected of exposure to chlorine gas, and their evacuation-related behaviors were observed in addition to analyzing the factors that affected the duration of their acute respiratory symptoms. Methods Behavioral characteristics during the incidence of the accidental chlorine gas leakage, the estimated time of exposure, and the duration of subjective acute respiratory symptoms were investigated. In addition, clinical examination, chest radiography, and dental erosion test were performed. As variables that affected the duration of respiratory symptoms, dose group, body weight, age, sex, smoking, work period, and wearing a protective gear were included and analyzed by using the Cox proportional hazard model. Results Of 47 workers exposed to chlorine gas, 36 (77 %) developed more than one subjective symptom. The duration of the subjective symptoms according to exposure level significantly differed, with a median of 1 day (range, 0–5 days) in the low-exposure group and 2 days (range, 0–25 days) in the high-exposure group. Among the variables that affected the duration of the acute respiratory symptoms, which were analyzed by using the Cox proportional hazard model, only exposure level was significant (hazard ratio 2.087, 95 % CI = 1.119, 3.890). Regarding the evacuation-related behaviors, 22 workers (47 %) voluntarily evacuated to a safety zone immediately after recognizing the accidental exposure, but 25 workers (43 %) delayed evacuation until the start of mandatory evacuation (min 5, max 25 min). Conclusions The duration of the subjective acute respiratory symptoms significantly differed between the low- and high-exposure groups. Among the 27 workers in the high-exposure group, 17 misjudged the toxicity after being aware of the gas leakage, which is a relatively high number.

Background: Statins are believed to reduce coronary heart disease by mechanisms in addition to their well-known cholesterol lowering effect. Hypothesis: We studied the effect of statins on expression of C-reactive protein (CRP), interleukin-6 (IL-6), adhesion molecules, and antioxidized low-density lipoprotein antibody (anti-oxLDL Ab) in patients with unstable angina (Braunwald class IIb or IIIb) undergoing coronary stenting. Methods: Consecutive 50 patients with unstable angina were included in the study. We classified the study subjects as patients using statins (Group A, n = 20, men 10, mean age 62 years) and patients notusing statins (Group B, n= 30, men 15, mean age 60 years). Results: Baseline levels of inflammatory markers were similar in the two groups. However, 24 h after coronary stenting, serum levels of CRP (2.00 vs. 4.63 mg/l, p < 0.05), intercellular adhesionmolecule-1 (ICAM-1) (217 vs. 261 ng/ml, p

Objectives The aim of this study was to examine the association between shift work and hyperuricemia among steel company workers. Methods We examined 1,029 male workers at a Korean steel company between June 6 and June 28, 2013. We conducted anthropometric measurements, questionnaire surveys, and blood tests. Hyperuricemia was defined as a serum uric acid concentration of ≥7.0 mg/dL. Logistic regression analyses were performed. In the full model, analysis was adjusted for covariates including age, body mass index, lifestyle factors, and comorbidities. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for all models. Results The participants included 276 daytime workers and 753 shift workers. Among daytime workers, 72 (26.1%) individuals had hyperuricemia, as did 282 (37.5%) individuals among shift workers (p

Background Abnormal serum gamma-glutamyltransferase (γ-GT) may be an early and sensitive marker for oxidative stress. This study was performed to evaluate the association between serum heavy metals and γ-GT concentration. Methods This study is a cross-sectional analysis based on data from Korean National Health and Nutrition Examination Survey (V-1, 2, 2010, 2011) regarding serum heavy metal concentrations (lead, mercury, and cadmium) as well as serum γ-GT. Serum heavy metals were categorized into tertiles, and serum γ-GT concentration was compared using an analysis of covariance test after relevant variable adjustments. In addition, we evaluated the odds ratio (OR) of having the highest tertile of serum γ-GT in each heavy metal tertile using logistic regression. Results The mean serum lead, mercury, and cadmium concentrations were 2.67, 5.08, and 1.02 µg/dL in men and 1.95, 3.60, and 1.21 µg/dL in women, respectively. Partial correlation showed a significant positive relation between each heavy metal and serum γ-GT concentration. Comparing serum γ-GT concentration by the tertile of each heavy metal, serum γ-GT concentration showed a significant increase as the tertiles of serum mercury and cadmium in men and that of serum mercury in women increased, but not with lead. The OR of having the highest tertile of serum γ-GT was significant for cadmium in men (OR, 4.02; 95% confidence interval [CI], 2.54 to 6.35) and mercury in women (OR, 2.00; 95% CI, 1.29 to 3.10) in the top tertile of each heavy metal. Conclusion Higher serum heavy metal concentration may be related with higher serum γ-GT concentration. In particular, serum cadmium in men and mercury in women showed significant correlation with serum γ-GT concentration.

Background The glomerular filtration rate (GFR) decreases with age, while parathyroid hormone (PTH) increases. There are a few reports only on the relationship between GFR and PTH under the category of serum 25-hydroxyvitamin D (25[OH]D) concentration. Methods Using the Korea National Health and Nutrition Examination Survey (KNHANES) data, a cross-sectional study was conducted on the association between serum 25(OH)D concentration, GFR and PTH in Korean adults aged 50 years or older. Serum PTH concentration was compared to the tertiles of GFR after adjustment for relevant variables. In addition, the serum PTH concentration was compared with the GFR under the category of serum 25(OH) D concentration (30 ng/mL). Results The mean estimated GFR (eGFR) was 74.8 mL/min in men and 73.1 mL/min in women. The mean PTH and 25(OH) D was 66.8 pg/mL, 20.5 ng/mL in men and 69.0 pg/mL, 18.2 ng/mL in women. The serum PTH concentration showed a significant negative correlation with the serum 25(OH) D and eGFR in both genders. The serum PTH concentration significantly increased at the lower tertile of eGFR in male adults In addition, a decrease of serum PTH concentration was marked in the vitamin D sufficient male adults (>30 ng/mL). Conclusion This present study demonstrated that serum PTH concentration showed negative correlation with eGFR, however, serum PTH increase may be minimized by maintaining proper serum 25(OH)D concentrations under similar eGFR status in Korean adults aged 50 and above.

In this paper, we derived the packet size and transmission protocol which guarantees high quality of data transmission as well as minimizes the initial speech transmission delay and the speech cut-off intervals caused by the packet errors. For this, we deducted expected time of data transmission in radiotelegraph using MIL-STD-188-220C. For VoIP communication in radio devices, it is revealed that the protocol which transmits short frames composed of 90ms sampling packets and 90ms re-transmission packets is efficient for 36kbps transmission systems, and in the systems of higher bit rates, the protocol which transmits long frames and then requests re-transmission when needed. The proper packet size and the transmission protocol which compromise multi-hop transmission for Ad-hoc radiotelegraph should be developed in future work.

The recovery of left ventricular ejection fraction (LVEF) appears to be prognostic of survival in congestive heart failure (CHF). The aim of our study was to evaluate which parameters appear to predict LVEF improvement in CHF.In all, 85 patients (age 64 +/- 12 years) with CHF and LVEF35% were enrolled. Doppler tissue imaging was performed on 5 basal and 5 midsegments to assess the time from R wave to peak systolic velocity (Ts). The standard deviation (SD) of Ts was an indicator of systolics synchrony. After at least 3 months of intensive medical therapy with beta-blocker and angiotensin-converting enzyme inhibitors, follow-up echocardiography was performed. By the change in LVEF, we divided patients into group I (5%, n = 47) and group II (/=5%, n = 38).Baseline clinical and echocardiographic parameters were similar in both groups. There was negative correlation between SD of Ts and change of LVEF ( r = -0.43, P.001). The multivariate analysis shows that SD of Ts and dose of beta-blocker were independent predictors of LVEF improvement.Myocardial systolic synchrony measured by Doppler tissue imaging is a predictor for LVEF improvement in severe CHF independently from QRS duration, cause of CHF, baseline LVEF, and chamber dimension.

ObjectivesWe sought to test whether the mechanical dyssynchrony assessed by tissue Doppler imaging (TDI) is a predictor of cardiac events in patients with congestive heart failure (CHF) and QRS duration ≤120 ms.BackgroundThe prevalence and prognostic value of mechanical dyssynchrony in patients with CHF and normal QRS duration have not been well clarified.MethodsA total of 106 patients (age 63 ± 11 years) with CHF and ejection fraction (EF) 37 ms) and Ts-diff (>91 ms) were associated with a significant increase in all clinical events. By multivariate analysis, Ts-diff (>91 ms) was an independent risk factor of clinical events and mortality regardless of age, EF, QRS duration, and use of beta-blocking agents. Mean event-free survival was 16.3 months (95% confidence interval [CI] 11.9 to 20.7) in patients with Ts-diff >91 ms and 31.6 months (95% CI 28.0 to 35.1) in those with Ts-diff ≤91 ms, respectively (p < 0.001).ConclusionsMyocardial dyssynchrony assessed by TDI is a powerful predictor of clinical events in CHF with normal QRS.

This paper describes a design guideline for CMOS drivers considering the simultaneous switching noise (SSN) on the power bus. This guideline employs two practical design parameters: the gate propagation delay of the active (or switching) drivers and the noise on the outputs of the quiet drivers. From the SSN model including the quiet drivers, the formulas for these design parameters are derived and used for constructing our design guideline. A safe area satisfying the given constraints on the design parameters is obtained as a function of the MOSFET channel width and the effective inductance of the power bus. The proposed formulas for design parameters and the design guideline for the drivers are confirmed through HSPICE simulation using a level 28 MOSFET model of a 0.35 /spl mu/m CMOS process.

We have analyzed the effect of via in multilayer printed circuit boards (PCBs) on signal integrity and signal delay time of high-speed digital systems. First, the techniques of the circuit modeling of via are discussed. Electrical behaviors of via in interconnects according to its circuit model are characterized through HSPICE simulation. Based on these results, we show that via can behave as being capacitive or inductive according to the characteristic impedance of signal lines, which is different from the fact that via is generally regarded as being only capacitive. The proposed electrical characteristic of via is verified by results of TDR/TDT measurement of through-hole type via in 8-layer PCBs. Second, the methodology of measurement of delay caused by via is proposed. Because it is so difficult to measure the electrical delay of signal passing through one via, we extract the delay caused by single via from measuring the delay when the signal passes through several vias. For an example, we obtained the signal delay time of 12 psec caused by a throughhole type via in 8-layer PCBs. For just two vias, the delay time is about 24 psec and it is about 8% of flight time of 5 cm signal line.

Objectives Uric acid concentration is known to increase the prevalence of metabolic syndrome by affecting its components, resulting in increased risk of cerebrovascular and cardiovascular diseases, and long-term lead exposure is known to affect this serum uric acid level. In this study, we aimed to examine the association between the causes of hyperuricemia and metabolic syndrome, and to determine whether an increased blood lead level affects hyperuricemia. Method Anthropometric measurements, surveys, and blood tests were conducted between May and June 2012 in 759 men working in the steelmaking process at a domestic steel company. Workers were divided into 2 groups according to the presence or absence of hyperuricemia, and an analysis was performed to examine its association with metabolic syndrome. In addition, the workers were divided into 3 groups according to the blood lead level to analyze the association between blood lead and hyperuricemia. Results The geometric mean (standard deviation) of the blood lead levels in the hyperuricemia group was significantly higher than that of the healthy group (3.8 [1.8] vs. 3.3 [1.8] μg/dL). The adjusted odds ratio for metabolic syndrome of the hyperuricemia group increased significantly to 1.787 (1.125–2.839) compared with the healthy group. In addition, the adjusted odds ratios for the occurrence of hyperuricemia in the tertile 2 (2.61–4.50 μg/dL) and tertile 3 groups (>4.50 μg/dL) according to blood lead level significantly increased to 1.763 (1.116–2.784) and 1.982 (1.254–3.132), respectively, compared with the tertile 1 group (< 2.61 μg/dL). Conclusion Hyperuricemia is believed to function as an independent risk factor for metabolic syndrome, while lead seems to increase the serum uric acid level even at a considerably low blood level. Therefore, attention should be given to patients with hyperuricemia and metabolic syndrome who are prone to lead exposure, and a prospective study should be conducted to identify their causal relationship.