• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.75-85
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• 2009

This work proposes a 13b 100MS/s 0.13um CMOS ADC for 3G communication systems such as two-carrier W-CDMA applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed ADC employs a four-step pipeline architecture to optimize power consumption and chip area at the target resolution and sampling rate. Area-efficient high-speed high-resolution gate-bootstrapping circuits are implemented at the sampling switches of the input SHA to maintain signal linearity over the Nyquist rate even at a 1.0V supply operation. The cascode compensation technique on a low-impedance path implemented in the two-stage amplifiers of the SHA and MDAC simultaneously achieves the required operation speed and phase margin with more reduced power consumption than the Miller compensation technique. Low-glitch dynamic latches in sub-ranging flash ADCs reduce kickback-noise referred to the differential input stage of the comparator by isolating the input stage from output nodes to improve system accuracy. The proposed low-noise current and voltage references based on triple negative T.C. circuits are employed on chip with optional off-chip reference voltages. The prototype ADC in a 0.13um 1P8M CMOS technology demonstrates the measured DNL and INL within 0.70LSB and 1.79LSB, respectively. The ADC shows a maximum SNDR of 64.5dB and a maximum SFDR of 78.0dB at 100MS/s, respectively. The ABC with an active die area of $1.22mm^2$ consumes 42.0mW at 100MS/s and a 1.2V supply, corresponding to a FOM of 0.31pJ/conv-step.

• Childhood Kidney Diseases
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• v.2 no.2
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• pp.110-117
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• 1998

Purpose : Henoch-$Sch{\ddot{o}}nlein$ purpura nephritis(HSPN) accompanied by nephrotic syndrome(NS) is known to have a poor prognosis and effective treatment is still controversial, even though both corticosteroids and immunosuppresant have been used for therapy. Cyclosporine A(CsA) is a well known immunosuppresant and widely used in renal transplantation and glomerular diseases especially steroid resistant. The aims of this study was to evaluate the therapeutic effect of CsA and to compare CsA with previously reported our data of rifampin(RFP) and azathioprine(AZA) in children with HSPN accompanied by NS. Methods : 37 HSPN patients with NS confirmed by renal biopsy were selected. Of these, 17 patients were treated with CsA(5 mg/kg/day) fur 6-8 months, 7 children were treated with RFP(10-20 mg/kg/day) for 9-12 months and 13 patients were treated with AZA(2 mg/kg/day) fur 8 months. Along with these regimens, low dose oral prednisolone(0.5-1 mg/kg, qod) was also used. Sequential renal biopsy was done in all patients 1 month after termination of treatment. Results : Complete remission rate of nephrotic syndrome was $58.8\%$ in CsA, $57.1\%$ in RFP and $38.4\%$ in AZA group after 17, 22, 11 months of mean follow-up period. Overall remission rate including partial remission was $88.2\%$ in CsA, $85.7\%$ in RFP and $84.6\%$ in AZA group. Disappearance rate of hematuria was $58.8\%$ in CsA, $57.1\%$ in RFP and $46.2\%$ in AZA group. Improvement of grade of clinical status was observed in 17 out of 17 CsA, 7 out of 7 RFP and 10 out of 13 AZA group. Improvement of pathologic class on sequencial renal biopsy was shown in 5 CsA($29.4\%$), none RFP($0\%$) and 2 AZA group($12.4\%$). Improvement on histologic immune-deposition was seen in 15 CsA($88.2\%$), 6 RFP($85.9\%$) and 4 AZA group($30.8\%$). Conclusion : In conclusion, Both CsA and RFP treated groups showed better result in complete remission rate of nephrotic syndrome and significant improvement of histologic immune-deposition compared with AZA treated group(p=0.004). So, we recommend CsA and REP rather than AZA for immunosuppresant treatment in HSPN with nephrotic syndrome.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.122-129
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• 2005

Purpose: Eosinophilic colitis is a disease characterized by gastrointestinal symptoms, peripheral eosinophilia, eosinophilic infiltration of the colonic wall. The etiology and pathogenesis of this disease is not clear and it is considered to be idiopathic. This study aimed to ascertain the clinical features, treatment and prognosis of eosinophilic colitis in early infancy. Methods: We reviewed 6 infants retrospectively, presented with bloody stool in early infancy, who were diagnosed with eosinophilic colitis in Pusan National University Hospital between August 2002 and February 2004. Results: Five males and one female were included. The mean age when bloody stool was identified was $79.2{\pm}56.1$ days (10~145 days). All but one infant with atopic dermatitis did not have other allergic diseases. Nobody had a family history of allergic disease. No specific dietary history in infants and their mothers related to food allergy was identified. Peripheral eosinophilia (total WBC count $11,763{\pm}3,498/mm^3$, eosinophils $17.0{\pm}4.3%$, absolute eosinophil count $2,044{\pm}996/mm^3$) was observed in all infants. Colonoscopy in six infants revealed diffuse erythema, congestion and granulation pattern of mucosa in the rectosigmoid colon. Histopathologic findings of colononic biopsies showed chronic inflammation with severe eosinophilic infiltration in the mucosa. Two infants were treated with hydrolyzed casein-based formula and four infants with prednisolone. Gastrointestinal symptoms and peripheral eosinophilia resolved completely with prednisolone and partially with a hydrolyzed casein-based formula. Relapse was not observed during the follow-up period. Conclusion: Our study demonstrated that there is no evidence of a definite relationship between eosinophilic colitis and food-allergic disorders. Clinical course and prognosis of infantile form of eosinophilic colitis is very favorable and treatment with prednisone was effective.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.2
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• pp.213-221
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• 2005

Purpose: Hemophagocytic syndrome (HPS) is characterized by persistent high fever, hepatosplenomegaly, cytopenias, hypertriglyceridemia, and/or hypofibrinogenemia. Hepatic manifestations including overt hepatic failure and fulminant hepatitis are common in HPS. Liver transplantation (LT) should be considered in a case of fulminant hepatitis by other than HPS, but LT is contraindicated and complete cure is possible by chemotherapy in HPS. Therefore, we conducted this study to define the characteristics of HPS presenting as severe acute hepatitis. Methods: Among the total of 23 patients diagnosed as HPS by bone marrow examination between 1994 and 2005 in Asan Medical Center, 11 cases presented as severe acute hepatitis were enrolled in this study. We analyzed the clinical features, laboratory findings and outcome retrospectively. Results: Seven (64%) of the 11 children with HPS and hepatitis were referred to pediatric gastroenterologist at first. The mean age of onset was 50 months. There was no case with family history of primary HPS. Epstein-Barr virus was positive in 4, and herpes Simplex virus was positive simultaneously in 1 case. As the presenting symptoms and signs, fever was present in 10, hepatosplenomagaly was noted in all and jaundice in 10. Anemia was observed in 10, thrombocytopenia in 10, leukopenia in 8, hypertriglyceridemia in 9, hypofibrinogenemia in 8 and hyperferritinemia in 7 cases, respectively. Nine children received chemotherapy including etopside. The overall mortality rate was 72% (8/11). Conclusion: HPS, which needs chemotherapy, should be considered as a cause of severe acute hepatitis especially when accompanied with prolonged high fever and cytopenias.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.1
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• pp.9-16
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• 2000

Purpose: The aim of this study was to determine how much acid exposure would occur in the proximal esophagus, both in normal and in patients with abnormal distal esophageal acid exposure. Methods: Fourty-six patients with suspected GER were classified into two groups, 24 patients with pathological distal reflux (group I); 22 patients with normal distal reflux (group II). The ambulatory dual-probe esophageal pH monitoring was performed for 18-24hr. The abnormal reflux was defined when the percent of time that pH was below 4.0 exceeded the 95th percentile of normal value. Results: The siginficant differences between distal and proximal esophageal pH recordings in group I persisted for all parameters except for the longest episode, but didn't persist in group II. At the distal esophageal site, the median percent time with pH<4.0 in group I was 19.3 and significantly higher than at proximal site. Half of patients with pathological distal reflux also had proximal acid reflux. Correlation coefficients between the distal and proximal esophageal sites in group I of the number of reflux episodes and time of the longest episode were 0.451 and 0.646 respectively. Conclusion: The 50 percent of patients with pathological distal acid reflux also had abnormal acid exposure in the proximal esophageal site. Therefore, we recommand simultaneous pH recordings from dual probe esophageal sites in children with gastroesophageal reflux.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.14 no.1
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• pp.67-73
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• 2011

Purpose: Recently, the incidence of acute hepatitis A has increased nationwide and is related to a low rate of IgG anti-HAV production. To establish effective measures for preventing hepatitis A virus infection, an epidemiologic study on the seroprevalence of anti-HAV is needed. Thus, we investigated the seroprevalence of IgG anti-HAV in children living in Gwangju and Jeonnam. Methods: IgG anti-HAV levels were measured in a total of 1,435 patients who visited Chosun University Hospital between January 2009 and December 2009. Results: The overall seropositve rate was 40.8% (586/1,435). The seropositive rates were 41% among children under the age of 1 year, 49.9% for children 1~5 years old, 51.1% among individuals 5~10 years old, 12.9% for individuals 10~15 years old, and 8.2% for subjects over 15 years old. There was no significant difference between genders in any group. The seropositive rates in Gwangju and Jeonnam were 57.3% and 32.9% for children under the age of 1 year, 52.5% and 44.3% for children 1~5 years old, 60.2% and 33.9% among children 5~10 years old, 14.1% and 9.7% for children 10~15 years old, and 10.8% and 4.2% for individuals over 15 years old. Conclusion: The results demonstrated the low rates of IgG anti-HAV, particularly among subjects over 10 years old, which suggests the possibility of increasing clinical HAV infection rates among adults in the near future. We should actively prevent the spread of hepatitis A virus. Vaccination is the most effective means of preventing hepatitis A virus transmission among persons at risk for infection. Hepatitis A vaccination is recommended for children who have low IgG anti-HAV seropositive rates.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.11 no.2
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• pp.179-186
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• 2008

Purpose: Feeding problems are common for typically developing children and have negative effects on physical, behavioral, and cognitive development. The purpose of the current study was to examine factors related to childhood feeding problems for typically developing children via parental reports. Methods: The feeding questionnaire developed by the authors and the Childhood Eating Behavior Inventory (CEBI) were administered to 796 parents of children who recruited from 2 pediatric outpatient clinics (n=379) and community (n=417). Problem eaters (PE) were identified by parental report and frequency analysis was conducted for types of feeding problems and its severity, problem behaviors during mealtime, the feeding methods of the parents, and the need for treatment. Results: The CEBI scores were significantly different between the PE and non-problem eaters (NPE), which suggests that the parental reports were reliable. The younger children had more feeding problems than the older children. The most frequent and severe feeding problems were selective eating and longer mealtimes across all age groups. One-half of the children had more than one problem behaviors during mealtime. Most parents of PE used ineffective methods to deal with children's behaviors during meal time, such as cajoling, which was related to their increased level of stress. Many parents reported their children need professional help for the feeding problems. Conclusion: Feeding problems are prevalent among children, especially younger children. Children with feeding problems showed a number of problem behaviors during mealtime and parental coping methods appeared to be ineffective. The need for treatment was considerable, thus the characteristics of this population must be acknowledged for providing proper treatment and advice.

• Pediatric Infection and Vaccine
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• v.6 no.1
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• pp.93-100
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• 1999

Purpose : For evaluation of acute Mycoplasma pneumoniae(M. pneumoniae) pneumonia in children, we have studied the Mycoplasma indirect particle agglutination test, cold hemagglutinin test, ESR, CRP, and total white blood cell counts and it's differential count retrospectively. Methods : The total numbers of patients whom compatible with diagnostic criteria of acute M. pneumoniae peumonia were 56 cases from Jan. to Dec. 1997. The diagnostic criteria were 1) onset of fever(${\geq}38.0^{\circ}C$) and coughing were within 7 days, 2) rhonchi and/or role was audible on chest, 3) pneumonic infiltration on chest X-ray, and 4) M. pneumoniae indirect particle agglutination test titer was higher than 1:640, or initial titer was less than 1:640 but increased more than 4 folds after week. We classified the enrolled patients according to initial antibody titer, such as soup A(${\leq}1:640$) and group B(${\geq}1:320$). We compared group A and B by demographic findings, clinical symptoms and signs, and laboratory findings. Results : 1) The male and female sex ratio was 1:1.4, and average onset age was $5.8{\pm}2.96$ years. 2) The average body temperature on admission was $38.5{\pm}0.1^{\circ}C$ and productive coughing was noticed in 52 cases(93%). 3) The average total white cell counts were $10,470{\pm}877.0/mm^3$ in group B patients, which was significantly higher compared to $7,761{\pm}508.5/mm^3$ in group A(p<0.014). 4) The average value of ESR and CRP were within normal range in both group. 5) The most common site of pneumonic infiltration was right lower lobe of lung in both groups. 6) There were no correlation between antibody titer and cold hemagglutinine titer in patients and cold hemagglutination titer were less than 1:64 in 25 cases(45%). Conclusion : The clinical manifestations of pneumonia, findings of chest x-ray, and indirect particle agglutination test were useful on diagnosis of M. pneumoniae pnumonia onset within 7 days, but cold hemagglutinin test was a little diagnostic meaning.

• Pediatric Infection and Vaccine
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• v.6 no.1
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• pp.107-115
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• 1999

Purpose : Enterobiasis is probably one of the most common parasitic infection world-wide. Human is the only known host of Enterobius vermicularis. Children are more commonly infected with Enterobius vermicularis than adults and infections are commonly recurred. In Korea, there is a high prevalence. So, we performed this study to evaluate the present status of Enterobius vermicularis infection among children in the Masan, Changwon areas and to determine the efficacy of flubendazole against this parasitic nematode. Methods : From November to December, 1997, urban and rural elementary school children and urban preschool children were examined for the presence of Enterobius vermicularis egg. All the children were examined once by an adhesive cellotape anal swab technique in the early morning at home by their parents guided by specific instructions for the technique. Results : 1) A total of 644 adhesive cellotape anal swab specimens was collected from 205 urban elementary school children, 290 rural elementary school children and 145 urban preschool children. Among them, 114(17.7%) were positive for Enterobius vermicularis eggs. There was no significant differences in the rate with regard to sex. 2) In the preschool children, the egg detection rate was 42(29.0%) out of 145 children. This rate was significantly higher compared with 72(14.4%) of 499 school children. 3) The egg detection rates in the rural and urban school children were 15.2, 13.7% respectively. There was no significant difference in both groups. In the 3rd grade and below in elementary school children, there was a higher rate compared with above 4th grade group. 4) In day care center where egg detection rate was high as 41%, the children were given two doses of 100mg flubendazole every 3 weeks, including staffs and family members. After treatment, egg detection rate fatted as 6%. Conclusion : Our data demonstrated that there was high prevalence of Enterobius vermicularis infection. In the light of these results, it is necessary to examine and treat children as soon as possible.

• Pediatric Infection and Vaccine
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• v.10 no.2
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• pp.186-192
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• 2003

Purposes : Recently, acute gastroenteritis broke out among the neonates transferred from postpartum care centers located in Seoul, and Gyeounggi area. Thus, we researched the cause, progress and characters of the disease by analyzing the cases from 9 hospitals in Seoul and Gyeounggi area. Methods : We conducted retrospective study of 33 neonates transferred from postpartum care centers from October 2001 to July 2002 : we divided the neonates into 2 groups. The severe group had any of following 5 conditions : blood pH <7.20, respiratory difficulty, mechanical ventilation, shock, and disseminated intravascular coagulation. And the rest were classified into the moderate group. Results : The severe group was significantly more aged than the moderate group(P= 0.005). Weight loss was significantly severe in the severe group(P=0.0512). In blood gas analysis, bicarbonate was less in the severe group than the moderate group(P=0.032). In the virus examination, rotavirus was detected in 7 cases, and astrovirus was detected in 1 case. In the severe group, 4 neonates were dead. Conclusion : In acute gastroenteritis of neonates, early diagnosis and treatment are important. Thus, the legislation of postpartum care center is needed, and the medical specialists should be stationed in postpartum care center. We assume that the severe group had severe conditions because they were treated comparatively late. However, to find out the cause of the disease and to cope with it, the nationwide epidemiologic study on acute gastrenteritis of neonates is needed.