Young Ho Kwak

A 120-MHz–1.8-GHz CMOS DLL-Based Clock Generator for Dynamic Frequency Scaling

A delay-locked loop (DLL)-based clock generator for dynamic frequency scaling has been developed in a 0.35-mum CMOS technology. The proposed clock generator can generate clock signals ranging from 120 MHz to 1.8 GHz and change the frequency dynamically in a short time. If the clock generator scales its output frequency dynamically by programming with the same last bit, it takes only one clock cycle to lock. In addition, the clock generator inherits advantages of a DLL. The proposed DLL-based clock generator occupies 0.07 mm2 and has a peak-to-peak jitter of plusmn6.6 ps at 1.3 GHz

Synergistic Inflammation Is Induced by Blood Degradation Products with Microbial Toll-Like Receptor Agonists and Is Blocked by Hemopexin

Detection of microbial components by immune cells via Toll-like receptors (TLRs) with subsequent induction of inflammation is essential for host defense. However, an overactive immune response can cause tissue damage and sepsis. The endogenous molecule hemoglobin and its derivative heme are often released into tissue compartments where there is infection in the presence of degrading blood. We found that hemoglobin synergizes with multiple TLR agonists to induce high levels of tumor necrosis factor and interleukin-6 from macrophages and that this synergy is independent of TLR4 and MyD88. In contrast, heme synergized with some but not all TLR agonists studied. Furthermore, the synergy of both hemoglobin and heme with lipopolysaccharide was suppressed by hemopexin, a plasma heme-binding protein. These studies suggest that hemoglobin and heme may substantially contribute to microbe-induced inflammation when bacterial or viral infection coexists with blood degradation and that hemopexin may play a role in controlling inflammation in such settings.

Niacin attenuates lung inflammation and improves survival during sepsis by downregulating the nuclear factor-κb pathway*

Objectives:To examine whether niacin attenuates lung inflammation and improves survival during sepsis and to determine whether the beneficial effects of niacin are associated with downregulation of the nuclear factor (NF)-&kgr;B pathway. Design:Prospective laboratory study. Setting:University laboratory. Subjects:Male Sprague-Dawley rats (n = 119). Interventions:To induce endotoxemia in rats, lipopolysaccharide (Escherichia coli, O26:B6) at a dosage of 10 mg/kg was injected into a tail vein and 10 mins later, vehicle, a low dose of niacin (360 mg/kg), or a high dose of niacin (1180 mg/kg) was administered once through an orogastric tube, respectively. Measurements and Main Results:We observed the survival of the subjects for 72 hrs. At 6 hrs postlipopolysaccharide, we euthanized animals and measured cytoplasmic phosphorylated inhibitor &kgr;B-&agr; and inhibitor &kgr;B-&agr; expressions, nuclear NF-&kgr;B p65 expression, NF-&kgr;B p65 DNA-binding activity, tumor necrosis factor-&agr;, and interleukin-6 gene expressions and histologic damages in lung tissues. We also measured nicotinamide adenine dinucleotide, reduced nicotinamide adenine dinucleotide phosphate, reduced glutathione, and malondialdehyde levels in lung tissues. High dose of niacin suppressed NF-&kgr;B activation and proinflammatory cytokine gene expressions in lung tissues, reduced histologic lung damages, and improved survival in endotoxemic rats. Furthermore, it increased nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and glutathione levels and decreased malondialdehyde level in lung tissues. Conclusions:High dose of niacin attenuated lung inflammation, reduced histologic lung damages, and improved survival during sepsis in rats. These therapeutic benefits were associated with downregulation of the NF-&kgr;B pathway.

Core temperature measurement in therapeutic hypothermia according to different phases: comparison of bladder, rectal, and tympanic versus pulmonary artery methods.

PURPOSE Comparisons of bladder, rectal and tympanic temperatures versus pulmonary artery (PA) temperature during different therapeutic hypothermia (TH) phases. METHODS Twenty-one patients admitted to our emergency department (ED) after out-of-hospital cardiac arrests were included in this study. For comparison, the temperature of four different sites, urinary bladder (BL), rectal (RE), tympanic membrane (TM) digital thermometers, and a Swan-Ganz catheter were used during TH, which were controlled by a surface cooling method. TH is divided into three phases: induction, maintenance, and rewarming phase. RESULTS In the induction phase, the mean differences between PA temperatures and those of the other methods studied were: BL (-0.24 ± 1.30°C), RE (-0.52 ± 1.40°C), and TM (1.11 ± 1.53°C). The mean differences between PA temperatures and those of the other methods in the maintenance phase were BL (0.06 ± 0.79°C), RE (-0.30 ± 1.16°C), and TM (1.12 ± 1.29°C); in the rewarming phase: BL (0.08 ± 0.86°C), RE (-0.03 ± 1.71°C), and TM (0.89 ± 1.62°C); and in the total phase: BL (0.04 ± 0.90°C), RE (-0.22 ± 1.44°C), and TM (1.03 ± 1.47°C). CONCLUSIONS The mean difference between BL and PA temperatures is lower than those in other sites during TH. On the contrary, there are larger differences between TM and PA temperatures when compared to other sites. The differences between RE and PA temperatures are comparatively less than those between TM and PA. However, RE temperature tends to be higher than the temperature recorded by a BL thermometer or Swan-Ganz catheter during the rapid induction phase.

A new age-based formula for estimating weight of Korean children

OBJECTIVES The objective of this study was to develop and validate a new age-based formula for estimating body weights of Korean children. METHODS We obtained body weight and age data from a survey conducted in 2005 by the Korean Pediatric Society that was performed to establish normative values for Korean children. Children aged 0-14 were enrolled, and they were divided into three groups according to age: infants (<12 months), preschool-aged (1-4 years) and school-aged children (5-14 years). Seventy-five percent of all subjects were randomly selected to make a derivation set. Regression analysis was performed in order to produce equations that predict the weight from the age for each group. The linear equations derived from this analysis were simplified to create a weight estimating formula for Korean children. This formula was then validated using the remaining 25% of the study subjects with mean percentage error and absolute error. To determine whether a new formula accurately predicts actual weights of Korean children, we also compared this new formula to other weight estimation methods (APLS, Shann formula, Leffler formula, Nelson formula and Broselow tape). RESULTS A total of 124,095 childrens data were enrolled, and 19,854 (16.0%), 40,612 (32.7%) and 63,629 (51.3%) were classified as infants, preschool-aged and school-aged groups, respectively. Three equations, (age in months+9)/2, 2×(age in years)+9 and 4×(age in years)-1 were derived for infants, pre-school and school-aged groups, respectively. When these equations were applied to the validation set, the actual average weight of those children was 0.4kg heavier than our estimated weight (95% CI=0.37-0.43, p<0.001). The mean percentage error of our model (+0.9%) was lower than APLS (-11.5%), Shann formula (-8.6%), Leffler formula (-1.7%), Nelson formula (-10.0%), Best Guess formula (+5.0%) and Broselow tape (-4.8%) for all age groups. CONCLUSION We developed and validated a simple formula to estimate body weight from the age of Korean children and found that this new formula was more accurate than other weight estimating methods. However, care should be taken when applying this formula to older children because of a large standard deviation of estimated weight.

The association between crowding and mortality in admitted pediatric patients from mixed adult-pediatric emergency departments in Korea.

Objective We aimed to investigate the effect of crowding on the hospital mortality of pediatric patients from adult-pediatric mixed emergency departments (EDs). Methods We used the National Emergency Department Information System database, which included demographic, clinical, diagnostic, and procedural information with all emergency patients visiting to 116 EDs from Korea since 2004. We enrolled EDs with mean length of stay of more than 6 hours. Study period was from January 2006 to December 2008. Pediatric patients younger than 15 years admitted from these EDs were study targets. We calculated the mean patient volume (mean number of patients in the ED) over 8-hour shift for each hospital. When the volume reached the highest quartile, the period was considered as crowded. Patients who came during the overcrowded period were defined as the crowded group. We performed a Kaplan-Meier analysis, and hazard ratio and 95% confidence intervals (95% CIs) were calculated using a Cox proportional hazards regression model. Results A total of 34 EDs and 125,031 admitted pediatric patients were included; 74,152 (59.3%) were male, and the mean age was 3.84 (95% CI, 3.82–3.86) years; 35,924 (28.7%) were determined as the crowded group. The 30-day mortality rates were 0.4% and 0.3% (P = 0.063) for the crowded group and for the noncrowded group, respectively. The hazard ratio for hospital mortality of the crowded group was 1.230 (95% CI, 1.019–1.558). Conclusions The ED crowding was associated with increased hazard for hospital mortality for pediatric patients in mixed EDs.

A One-Cycle Lock Time Slew-Rate-Controlled Output Driver

A low-power output-on-demand slew-rate-controlled output driver is presented. It has an open-loop digital scheme and a one-cycle lock time applicable to high-speed memory interfaces. The output driver maintains slew rate between 2.1V/ns and 3.6V/ns for the SSTL interface. Fabricated in a 0.18mum CMOS process, the control block of the proposed driver occupies 0.009mm2 and consumes 13.7mW at 1Gb/s. No external resistance is needed to calibrate the output resistance of the output driver.

A 1.62 Gb/s–2.7 Gb/s Referenceless Transceiver for DisplayPort v1.1a With Weighted Phase and Frequency Detection

This paper proposes a 2.7 Gb/s referenceless transceiver with weighted PFD for frequency detection of random signals. A single loop referenceless CDR is also proposed to overcome the disadvantages of a dual loop CDR. The ANSI 8b/10b encoder & decoder with the scrambler, the serializer & de-serializer, and the output driver with pre-emphasis are included in the proposed transceiver architecture for DisplayPort v1.1a. The jitter of the generated clock at the Tx PLL is 3.28 psrms at 2.7 Gb/s with 1.2 V supply. The eye opening of the transmitter output with 3 m cable is 0.54 UI. The measured jitter of the recovered clock at the CDR is 1.57 psrms, and BER is less than 10-12. The receiver consumes 23 mW at 2.7 Gb/s with 1.2 V supply. The CDR core and transceiver occupy 0.07 mm2 and 0.94 mm2, respectively, in a 0.13 μm 1P8M CMOS process.

Utilization of emergency department by children in Korea

This study was conducted to examine the nation-wide emergency department (ED) utilization pattern by children in Korea. Most referral hospital EDs provide their essential ED information to the National Emergency Medical Center through the National Emergency Department Information System (NEDIS). We analyzed the NEDIS data on pediatric visits (< 19 yr old) during three years, from June 1, 2008 to May 31, 2010. A total of 2,072,664 children visited 124 EDs during the study period, and this patient population comprised 31.2% of the total ED visits. Male patients with a mean age of 5.44 (± 5.40 SD) yr comprised 59.1% of the ED pediatric visits. Among all age groups, the 1-4-yr-old group was the largest (42.3%). The most common mode of arrival was non-emergency medical service (EMS) (90.7%), and only 4.2% of patients used EMS transport. Common chief complaints in infants were fever (37.4%), whereas many older children presented to the EDs with abdominal pain (15.4%). The ratio of disease versus injury as the cause of ED visits was 2.5:1. Most patients were discharged (81.2%), and 15.3% were admitted. In conclusion, the most common age group who are brought to EDs in Korea is 1 to 4 yr-old young children, and common chief complaints of the visiting children are age-dependent, such as fever in younger children and abdominal pain and headache in older children. We need more improved and organized emergency medicine service system for children in Korea.

Epidemiology of Traumatic Head Injury in Korean Children

The aim of this study was to elucidate the epidemiology of traumatic head injury (THI) among Korean children. A prospective, in-depth trauma survey was conducted in five teaching hospitals. Data from all of the children who attended the emergency department (ED) were analyzed. From June 2008 to May 2009, 2,856 children with THI visited the 5 EDs. The average age of the subjects was 5.6 (SD ± 4.9) yr old, and 1,585 (55.5%) were 0-4 yr old. The male-to-female ratio was 2.3 to 1 (1,979 vs 877). Consciousness levels of the subjects were classified according to the Glasgow Coma Scale (GCS), and 99.1%, 0.6%, and 0.4% were determined as mild, moderate, or severe injury, respectively, according to the GCS categorization. Most injuries occurred at home (51.3%), and the most common mechanism of injury was collision (43.2%). With regard to outcome, 2,682 (93.9%) patients were sent home, and 35 (1.2%) were transferred to another hospital. A total of 133 (4.7%) patients were hospitalized, and 38 (1.3%) underwent surgery. The incidence and characteristics of pediatric THI in Korea are affected by sex, location and injury mechanism.