• Bulletin of the Korean Chemical Society
• /
• v.22 no.11
• /
• pp.1248-1254
• /
• 2001

The conformations and energies of p-tert-butylcalix[4]crown-6-ether (1) and its alkyl ammonium complexes have been calculated by ab initio HF/6-31G quantum mechanics method. The cone conformation was found to be most stable for free host 1. We hav e determined the binding site of these host-guest complexes focusing on the crown-6-ether or p-tert-butylcalix[4]arene pocket of the cone conformation of host molecule 1. The primary binding site of host 1 for the recognition of alkyl ammonium guests was confirmed to be the central part of the crown moiety of cone conformation. The complexation energy calculations revealed that the ammonium cation without alkyl group showed the highest complexation efficiency when combined with host 1, that is in satisfactory agreement with the experimental results.

• Pediatric Infection and Vaccine
• /
• v.12 no.2
• /
• pp.186-194
• /
• 2005

Purpose : Hepatitis A viral infections have been continued after re-emerging since mid 1990s in Korea. The incidence of this disease has been increased in young adults younger than 30 years of age since 2000. This study was performed to evaluate the prevalence of antibody to hepatitis A in Korea(two regions; Incheon and Changwon) in 2005, and was compared with the results of similar studies in mid 1990s. Methods : The study was conducted from January 2005 to June 2005, and consisted of 1,301 enrolled subjects, neonates to 50 years old, living in Incheon and Changwon in Korea. All sera were frozen and stored at $-70^{\circ}C$ until assayed. Anti-HAV IgG antibodies were measured by microparticle enzyme immunoassay(HAVAB, Abbott Lab., IL, USA). Results : The prevalence of anti-HAV IgG was 61.1% in infants younger than 1 year old, 30.5% in 1~5 years, 14.6% in 6~10 years, 1.7% in 11~15 years, 6.5% in 16~20 years, 36.6%in 21~30 years, 77.5% in 31~40 years, and 99.8% in 41~50 years. Statistical differences were not found between male and female, but there was statistical difference in 6~10 years old age group between the two areas. Conclusion : Our study indicate that the prevalence of antihepatitis A virus antibody has shifted from children to old adolescents and young adults. This result suggests that the risk of sudden outbreaks or increasing incidence of hepatitis A viral infections in young adults may be expected in our society. The preventive strategies of hepatitis A including vaccination should be prepared.

• Pediatric Infection and Vaccine
• /
• v.7 no.1
• /
• pp.120-128
• /
• 2000

Purpose : Active immunization against hepatitis A with an inactivated vaccine reveals excellent immunogenicity, tolerability and protective efficacy. Inactivated hepatitis A vaccines have been selectively used since 1996 in Korea to prevent hepatitis A. This study was performed to assess the immunogenicity and reactogenicity after two doses of HM175 strain hepatitis A vaccine in healthy Korean children. Methods : 128 healthy children(M/F; 65/63) aged 1 to 15 years, who were seronegative for hepaitatis A, participated in this study. A alum-adsorbed vaccine containing 720 EL.U of antigen form HM175 hepatitis A strain per 0.5 mL dose was injected intramuscularly on the deltoid area. The second dose was given 6 months later, Anti-HAV antibodies were measured by ELISA before and 1 month after each vaccination to assess the immunogenicity. Any local and general adverse events were reported by patients parents with the prepared questionnaire after each vaccination. Results : 120 volunteers(M/F; 60/60) completed the whole series of the study. Seroconversion occurred in all cases after primary and booster vaccination. The mean anti-HAV antibody titer after primary vaccination was 389.2mIU/mL, and 3,609mIU/mL after booster vaccination. And levels of anti-HAV antibodies after booster immunization were significantly higher in female children. The most common local adverse event was soreness on the injection site, but it was mild and resolves within 3 days. Fever was not reported after booster vaccination. Conclusion : Based on these data, we conclude that the inactivated HM175 strain hepatitis A vaccine is highly immunogenic and tolerable in healthy Korean children.

• Journal of Yeungnam Medical Science
• /
• v.24 no.2
• /
• pp.170-178
• /
• 2007

Background : The incidence of acute hepatitis A in adults has recently been increasing. This study was conducted to investigate the epidemiology and clinical characteristics of acute hepatitis A in Daegu province over the past 10 years. Materials and Methods : We reviewed the medical records of 55 patients (male/female: 34/21), who were diagnosed with acute hepatitis A by confirmation of the IgM anti-HAV between January 1998 and June 2007. Results : The mean age was $29.7{\pm}10.3$ years (range; 17-65 years). The incidence was most common between March and June (56.1%), in the third and fourth decades of life (78.2%) and 90.9% (50/55) of the patients were diagnosed from 2003 to present. The common symptoms included anorexia, nausea or vomiting (69.1%), fever and chills (49.1%), myalgia (47.3%), weight loss (47.3%), fatigue (40.0%), abdominal pain (36.4%), diarrhea (9.1%) and pruritus (5.5%). The mean duration of hospital stay was $8.6{\pm}3.4$ days (range; 3-20 days). The route of transmission was identified in only 11 patients (20.0%); 7 patients (12.7%) traveled (abroad or domestic), 2 patients (3.6%) ingested raw food and 2 patients (3.6%) had friends with acute hepatitis A. Fifty four patients recovered without complication; one patient developed fulminant hepatitis and recovered after a liver transplantation. Conclusion : The incidence of acute hepatitis A in adults is increasing. Because of the cost of treatment and potential for serious disease, persons, under 40 are recommened to have hepatitis A vaccination and confirmation of IgG anti-HAV.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.15 no.2
• /
• pp.91-99
• /
• 2012

Purpose: The aims of this study was to compare and evaluate the clinical characteristics, laboratory data, and prognosis for infants under age 1 year with CMV hepatitis and those with viral hepatitis of unknown etiology. Methods: A retrospective study was conducted of infants under age 1 year who were admitted with acute hepatitis. The exclusion criteria consisted of: autoimmune, genetic, metabolic, toxic, HAV, HBV, HCV, toxoplasma, rubella, herpes simplex, and Epstein-Barr virus. The 30 patients included were divided into two groups based on markers for CMV (IgM anti-CMV, CMV PCR in urine, CMV culture in urine). Results: The median age of patients (n=15) was 2.8 months. No other organ involvement was detected in any patient. Peak serum total bilirubin levels (n=4) ranged from 2.6 to 6.7 mg/dL. Peak serum ALT levels ranged from 51 to 1,581 IU/L. The duration of ALT elevation ranged from 1.5 weeks to 26 weeks (median 9 weeks). All had recovered in full without ganciclovir; there were no cases of hearing loss. The median age of controls (n=15) was 2.5 months. Peak serum total bilirubin levels (n=4) ranged from 1.6 to 9.1 mg/dL. Peak serum ALT levels ranged from 26 to 1,794 IU/L. No significant differences were observed between both groups regarding the peak serum ALT levels, peak serum total bilirubin levels, duration of hyperbilirubinemia and ALT elevation. Conclusion: Although it was not possible to differentiate congenital infection with perinatal infection in this study, the prognosis of patients with CMV hepatitis without other organ involvement was good without ganciclovir treatment.

• Journal of Powder Materials
• /
• v.11 no.6 s.47
• /
• pp.515-521
• /
• 2004

Fe(C) nanocapsules were prepared by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl $(Fe(CO)_5)$. Their characterizations were studied by means of X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The long-chained Fe(C) nanocapsules hav-ing the mean size of under 70 nm could be obtained below $1100^{\circ}C$ in different gas flow rates. The particle size of the powders was increased with increasing decomposition temperature, but it was decreased with increasing CO gas flow rate. The Fe powders produced at $500^{\circ}C$ consisted of three layers of ${\alpha}$-Fe/$Fe_3C$/amorphous phases, but it had two phase core-shell structure which consited of $Fe_3C$ phase of core and graphite of shell at $1100^{\circ}C$.

• Archives of Pharmacal Research
• /
• v.27 no.9
• /
• pp.937-943
• /
• 2004

Recent investigations have shown that certain flavonoids, especially flavone derivatives, inhibit nitric oxide (NO) production by inducible NO synthase (iNOS) in macrophages, which contrib-ute their anti-inflammatory action. For the purpose of finding the optimized chemical structures of flavonoids that inhibit NO production, various A- and B-ring substituted flavones were syn-thesized and evaluated for their inhibitory activity using lipopolysaccharide-treated RAW 264.7 cells. It was found that the optimal chemical structures were A-ring 5,7-dihydroxyflavones hav-ing the B-ring 2＇,3＇-dihydroxy or 3＇,4＇-dihydroxy or 3＇,4＇-hydroxy/methoxy (methoxy/hydroxy) groups. These structurally optimized compounds were revealed to be down-regulators of iNOS induction, but not direct iNOS inhibitors. Of these derivatives that were evaluated, 2＇,3＇,5,7-tet-rahydroxyflavone and 3＇,4＇,5,7-tetrahydroxyflavone (Iuteolin) showed the strongest inhibition. The $IC_{50}$/ values for these compounds were 19.7 and 17.1 11M, respectively. Therefore, these compounds may have a potential as new anti-inflammatory agents.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.3
• /
• pp.285-292
• /
• 2020

This paper introduces a new computational efficient Dilution of Precision (DOP)-based landmark exclusion method while ensuring the safety of the LiDAR-based navigation system that uses an innovation-based Nearest-Neighbor (NN) Data Association (DA) process. The NN DA process finds a correct landmark association hypothesis among all potential landmark permutations using Kalman filter innovation vectors. This makes the computational load increases exponentially as the number of landmarks increases. In this paper, we thus exclude landmarks by introducing DOP that quantifies the geometric distribution of landmarks as a way to minimize the loss of integrity performance that can occur by reducing landmarks. The number of landmarks to be excluded is set as the maximum number that can satisfy the integrity risk requirement. For the verification of the method, we developed a simulator that can analyze integrity risk according to the landmark number and its geometric distribution. Based on the simulation, we analyzed the relationship between DOP and integrity risk of the DA process by excluding each landmark. The results showed a tendency to minimize the loss of integrity performance when excluding landmarks with poor DOP. The developed method opens the possibility of assuring the safety risk of the Lidar-based navigation system in real-time applications by reducing a substantial amount of computational load.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.7
• /
• pp.185-197
• /
• 1996

We have adopted the strain compensated PBH(planar buried heterostructure) - LD in which the MQW active layer consisted of 1.4% compressively strained GainAsP (E$_{g}$ = 0.905eV) wells and 0.7% tensile strained GaInAsP(E$_{g}$ = 1.107eV) barriers grown by metal organic vapor phase epitaxy (MOVPE). We hav einvestigated effects of number of wells and the structure of the separate confinement heterostructure (SCH) layer in the strain-compensated MQW-PBH-LD. The threshold current, the external quantum efficiency, the transparency current density J$_{o}$, and the gain constant .beta. have been evaluated for uncoated MQW-PBH-LD. As the number of wells increases, the internal quantum efficiency and the transparency current density decreases, whereas the gain contant increases. The small width of the SCH layer shows the large internal quantum efficiency. The small internal loss and the large gain constant have been obtained by inserting the large bandgap SCH layer.

• Proceedings of the KSMRM Conference
• /
• 2001.11a
• /
• pp.174-174
• /
• 2001

Purpose： Dimensions of body RF coil composed of 4 rectangular loops for low field open MRI hav been optimized. The design result shows the field inhomogeneity of B1 field below 1.5 dB in the 25 cm DSV can be achieved. Method： Our low field RF coil is composed of 4 rectangular strip loops that assumed to b located at both the bottom and top sides of permanent magnet. All the loops have identica dimensions and current amplitude. First, the inductance of a loop is calculated. Second, the current distribution on the coil strip is calculated by using finite difference time doma method (FDTD). It takes as much as 4 days in FDTD simulation for low frequency RF field That's why the electrical dipole radiation method is used for simulation. With the curren distribution obtained using the FDTD simulation, for various dimensional parameters th magnetic field has been calculated by electric dipole radiation method, where the curren elements are regarded as electric dipole radiation sources. The field pattern from electri dipole radiation is almost same as that from FDTD simulation. Also, it is same as that fro the result using the Viot-Savart equation, for far tone radiation term becomes zero and th Bl field amplitude of near one radiation is the same as the B field due to static current The field homogeneity is calculated in the 25 cm BSV.