• 한국환경보건학회지
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• 제38권1호
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• pp.31-41
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• 2012

Objectives: Biomonitoring is used to assess human environmental exposures. Urinary biomonitoring data are typically adjusted to a constant creatinine concentration to correct for variable dilutions among spot samples. Our objective was to investigate urinary creatinine concentrations by region, gender, age and lifestyle. Methods: We studied urinary creatinine concentrations in 6,286 Koreans aged 20 years old and older who participated the fourth Korea National Health and Nutrition Survey (KNHANES IV) in 2009. Urinary creatinine concentration analysis used the Jaffe method. Results: The average urinary creatinine concentration of 6,286 Koreans was 158.99 mg/dl. The urinary creatinine concentration was significantly higher among men (184.97 mg/dl) than women (130.02 mg/dl). In both men and women, urinary creatinine concentrations were significantly different according to age group (p < 0.01). Whereas the urinary creatinine concentration of men significantly differed with smoking in adjusted comparison analysis, that of women significantly differed by education level. Ninety-two percent of urinary creatinine concentration was included within WHO guidelines effective range(30 mg/dl ${\leq}$ urinary creatinine concentration ${\leq}$ 300 mg/dl). In multiple regression analysis, creatinine was influenced by gender, age and body mass index (BMI). Conclusions: The urinary creatinine value obtained from representative samples of adult Koreans aged 20 year and older in KNHANES IV 2009 could be used as a reference value for other nationally studied surveys, such as abandoned metal mine surveys and surveys for industrial complexes.

• 대한치과보철학회지
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• 제39권6호
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• pp.641-658
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• 2001

All-ceramic restorations have become an attractive alternative to porcelain-fused-to-metal crowns. In-Ceram, and more recently IPS Empress 2 were introduced as a new all-ceramic system for single crowns and 3-unit fixed partial dentures. But their strength and marginal fit are still an important issue. This study evaluated the fracture resistance and marginal fit of three systems of 3 unit all-ceramic bridge fabricated on prepared maxillary anterior resin teeth in vitro. The 3 all-ceramic bridge systems were: (1) a glass-infiltrated, sintered alumina system (In-Ceram) fabricated conventionally, (2) the same system with copy-milled alumina cores (copy-milled In-Ceram), (3) a heat pressed, lithium disilicate reinforced glass-ceramic system (IPS Empress 2). Ten bridges of each system with standardized design of framework were fabricated. All specimens of each system were compressed at $55^{\circ}$ at the palatal surface of pontic until catastrophic fracture occurred. Another seven bridges of each system were fabricated with standard method. All of the bridge-die complexes were embedded in epoxy resin and sectioned buccolingually and mesiodistally. The absolute marginal discrepancy was measured with stereomicroscope at ${\times}50$ power. The following results were obtained: 1. There was no significant difference in the fracture strength among the 3 systems studied. 2. The Weibull modulus of copy-milled In-Ceram was higher than that of In-Ceram and IPS Empress 2 bridges. 3. Copy-milled In-Ceram($112{\mu}m$) exhibited significantly greater marginal discrepancy than In Ceram ($97{\mu}m$), and IPS Empress 2 ($94{\mu}m$) at P=0.05. 4. The lingual surfaces of the ceramic crowns showed smaller marginal discrepancies than mesial and distal points. There was no significant difference between teeth (incisor, canine) at P=0.05. 5. All-ceramic bridges of three systems appeared to exhibit sufficient initial strength and accept able marginal fit values to allow clinical application.

• 분석과학
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• 제8권4호
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• pp.869-876
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• 1995

The active sites of the nickel and iron-containing enzyme, carbon monoxide dehydrogenase (CODH) from clostridium thermoaceticum were investigated using Electron Paramagnetic Resonance (EPR) technique. CODH exhibits several spectral features called NiFeC, $g_{ave}=1.82$, $g_{ave}=1.86$. FCII signals which are originated from different clusters in this enzyme. CODH is know to catalyze two different kinds of reactions - acetyl-CoA synthesis and CO oxidation. The acetyl-CoA synthesis activity can be followed by monitoring CO/acetyl-CoA exchange. The addition of 1,10-phenanthroline (phen) to CODH selectively destroyed the CO/acetyl-CoA exchange activity and eliminated the NiFeC signal completely. CO oxidation activity and other EPR signals were unaffected. Such behavior demonstrates that CODH has two distinct active sites and that the NiFe complex is only responsible for the CO/acctyl-CoA exchange activity. Phen caused the removal of only 30% of Ni in the NiFe complex ($0.3Ni/{\alpha}{\beta}$) as shown by the quantitative metal analysis. The phen-treated CODH could be reactivated fully by incubation In $Ni^{2+}$ solution. Radioactive $^{63}Ni^{2+}$ was used to quantitate the amount of the $Ni^{2+}$ incorporated into phen-treated enzyme and showed that the amount was the same as the removed by the phen treatment. i.e. $0.3Ni/{\alpha}{\beta}$. This indicates that only 30% of NiFe complexes are labile and responsible for the CO/acctyl-CoA exchange activity, the other 70% are non-labile and have no exchange activity. This is the first clear evidence that the NiFe complex is heterogencous and labile and non-labile Ni sites arc interacting differently with substrates and chelating agents like phen.

• 분석과학
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• 제8권3호
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• pp.221-227
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• 1995

$Ca^{2+}$에 대하여 특이한 선택성을 보이는 광섬유형광센서에 대하여 연구하였다. 이 센서는 $Ca^{2+}$과 형광성 킬레이트를 형성하는 단백질 Calmodulin(CaM)을 사용하였으며, 두 갈래로 된 광섬유 다발의 끝면에 플루오르세인 이소티오시아네이트로써 형광 표지된 Calmodulin(FCaM)으로 만든 용액을 투석막 안에 넣어서 제작하였다. 이 센서의 감응 메카니즘은 FCaM이 $Ca^{2+}$과 결합하여 킬레이트를 형성할 때에 나타나는 형광 스펙트럼의 이동 현상을 바탕으로 한다. CaM은 $Ca^{2+}$과 결합할 때에 형태변화를 일으키며, 이로 인해 유발되는 FCaM의 형광세기 변화로써 농도를 결정하였다. 광전자증배관으로 형광의 세기를 측정하여 $Ca^{2+}$에 대한 검정곡선을 작성하였으며, 센서의 $Ca^{2+}$에 대한 검출한계와 $Mg^{2+}$, $Eu^{3+}$, $La^{3+}$들에 의한 방해효과, 감응 시간 및 수명을 조사하였다.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3118-3122
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• 2010

The water soluble redox polymer, poly(N-vinylimidazole) complexed with Os(4,4'-dichloro-2,2'-bipyridine)$_2Cl]^+$ (PVI-[Os(dCl-bpy)$_2Cl]^+$), was electrodeposited on the surface of a glassy carbon electrode by applying cycles of alternating square wave potentials between 0.2 V (2 s) and 0.7 V (2 s) to the electrode in a solution containing the redox polymer. The coordinating anionic ligand, $Cl^-$ of the osmium complex, became labile in the reduced state of the complex and was substituted by the imidazole of the PVI chain. The ligand substitution reactions resulted in crosslinking between the PVI chains, which made the redox polymer water insoluble and caused it to be deposited on the electrode surface. The deposited film was still electrically conducting and the continuous electrodeposition of the redox polymer was possible. When cycles of square wave potentials were applied to the electrode in a solution of bilirubin oxidase and the redox polymer, the enzyme was co-electrodeposited with the redox polymer, because the enzymes could be bound to the metal complexes through the ligand exchange reactions. The electrode with the film of the PVI-[Os(dCl-bpy)$_2Cl]^+$ redox polymer and the co-electrodeposited bilirubin oxidase was employed for the reduction of $O_2$ and a large increase of the currents was observed due to the electrocatalytic $O_2$ reduction with a half wave potential at 0.42 V vs. Ag/AgCl.

• 대한화학회지
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• 제39권1호
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• pp.35-39
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• 1995

백금과 로듐 모두 미량으로 존재할 때 펄스 차이 폴라로그래피법으로 동시 정량할 수 있는 용액조건을 확립하였다. 포름알데히드 0.004%(w/v)-히드라진 0.0012$(w/v)-황산 0.75 M의 조건에서 가장 예민한 수소 촉매파를 얻을 수 있었다. 이 조건에서 단일 금속의 검출 한계는 $7.3{\times}10^{-11}\; M\; Pt$ 그리고 $3.2{\times}10^{-11}\; M\; Rh$이었다. 이 농도범위에서 로듐(10배 이상)과 이리듐(100배 이상)만이 백금을 방해하였다. 로듐은 어떠한 여타 백금족 원소(1000배 이상의 백금, 500배의 이리듐 존재하에서도)의 방해도 받지 않았다.

• Macromolecular Research
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• 제15권2호
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• pp.95-99
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• 2007

The most recent developments in two areas: (a) synthesis of inorganic particles with control over size and shape by polymer additives, and (b) synthesis of inorganic-polymer hybrid materials by bulk polymerization of blends of monomers with nanosized crystals are reviewed. The precipitations of inorganics, such as zinc oxide or calcium carbonate, in presence and under the control of bishydrophilic block or comb copolymers, are relevant to the field of Biomineralization. The application of surface modified latex particles, used as controlling agents, and the formation of hybrid crystals in which the latex is embedded in otherwise perfect crystals, are discussed. The formation of nano sized spheres of amorphous calcium carbonate, stabilized by surfactant-like polymers, is also discussed. Another method for the preparation of nanosized inorganic functional particles is the controlled pyrolysis of metal salt complexes of poly(acrylic acid), as demonstrated by the syntheses of lithium cobalt oxide and zinc/magnesium oxide. Bulk polymerization of methyl methacrylate blends, with for example, nanosized zinc oxide, revealed that the mechanisms of tree radical polymerization respond to the presence of these particles. The termination by radical-radical interaction and the gel effect are suppressed in favor of degenerative transfer, resulting in a polymer with enhanced thermal stability. The optical properties of the resulting polymer-particle blends are addressed based on the basic discussion of the miscibility of polymers and nanosized particles.

• 지질공학
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• 제12권2호
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• pp.203-214
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• 2002

벤토나이트의 중금속 흡착에 대한 다양한 실험적 조건을 만족시키기 위하여 박스-벤켄(Box-Benken)의 통계적 모델을 적용하였다. 모델에 의하여 pH, 중금속의 초기농도, HCO$_3$을 변수로 하고, 각 변수에 대한 농도를 3차원으로 설정하여 벳치 실험을 실시하였다. 실험에 선택된 중금속은 Pb, Cu, Zn, Cd 4종이다. 중금속의 흡착거동에 대한 각 변수들의 영향을 표면반응 분석을 통하여 3차원으로 모델링하였다. 중금속의 흡착제거에 중금속의 초기농도와 pH가 거의 비슷한 정도로 큰 영향을 미치고 중탄산은 큰 영향을 미치지 못한다. 중금속간의 흡착경쟁은 Pb>Cu>Zn>Cd의 순서를 보인다. 아울러 pH 변화가 중금속 흡착에 미치는 영향을 실험적 및 열역학적 분석을 통하여 알아보았다. 중금속의 수산화 화합물과 탄산염 복합체의 형태로 침전이 흡착제거에 중요한 변수임이 밝혀졌다. WATEQ4F 열역학 프로그램에 의한 종분포 모델링 결과가 흡착실험결과와 다소 상이함을 보이므로 프로그램의 열역학 자료의 수정이 필요하다.

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2002년도 International Symposium on Magnetic Resonance
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• pp.70-71
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• 2002

Exchange-coupled cluster of transition-metal ions are relevant to many different scientific areas, ranging from chemistry to solid-state physics, biology, material science and has been the subject of much research in recent years(1,2). Single crystal EPR spectroscopy works as a very effective tool for the measurement of J values for small exchange interactions. This makes EPR technique very suitable for detection of weak exchange coupling transmitted over long distances via extended atomic and melecular bridges. Large polyoxometallates (3) may provide ideal structural environments for the study of interactions between paramagnetic ions. The detailed nature of magnetic interaction (positive sign and magnitude of J~0.006 $cm^{-1}$ /) was clearly determined for di-copper(II) system by single crystal EPR spectroscopy (4). The single-triplet (S-T) transitions are forbidden by different symmetries of the wave functions. However, when the singlet ground state is mixed into triplet states, the S-T transitions can be allowed and observed as weak lines. These weak S-T lines are positioned symmetrically with respect to the main transitions in the distance equals to 2J from the center of the spectrum. This lines allow one to determine the J-value with very high accuracy when │J│ ＜ hv 0.32 $cm^{-1}$ /. Unfortunately, the S-T transitions in the single crystal were detected by EPR method only in a few complexes until now. We have measured single-triplet transition lines for several magnetically coupled cluster systems and determined their J values accurately. The temperature dependency of J was studied by monitoring the changes in S-T.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.529-532
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• 1999

본 연구에서는 유기 전기 발광 소자에서 녹색 발광층으로 사용되는 terbium(Tb) complexes와 europium(Eu) complex, 정공 수송층으로 사용되는 TPD (N, N\`-diphenyl-N,\`(3-methylphenyl)-1, 1\`biphenyl-4, 4\`-diamine), 그리고 전자 수송층으로 사용되는 Alq$_{3}$ (trois(8-hydroxyquinolino)aluminum), Bebq$_2$들의 Uv/Vis. 홉광도와 PL 스펙 트럼과 같은 광학적 특성을 조사하였으며 또한 이러한 물질들을 이용하여 다양한 종류의 유기 전기 발광 소자를 제작하고 제작된 소자들의 전류밀도-전압-조도 등의 전기 . 광학적 특성을 조사하였으며, 그 결과 다 음과 같은 결곤을 얻을 수 있었다. 다양한 ligand를 갖는 Tb complex들의 경우에도 EL 스펙트럼의 파장대 (wavelength)는 546nm~548nm의 녹색 발광을 하는 것을 알 수 있었고, 제작된 소자 중에서 Tb(ACAC)$_3$(Phen) 을 발광충으로 하고, TPD, 그리고 Bebq$_2$를 각각 정공 수송층, 전자 수송 층으로 한 소자가 가장 낮은 구동 전압을 갖는다는 것을 확인하였으며 logJ-logV 특성에서도 모든 전계 구간에서 이러한 구조의 소자가 가장 높은 전류밀도를 나타냈으며 저 전계 구간에서 전류밀도 타이가 가장 컸다. 소자의 전류밀도와 휘도의 관계에 있어서는 제작된 네 종류의 소자 중 Tb(ACAC)3(Cl-Phen)를 발광층으로 하고 TPD, 그리고 Bebq2를 각각 정공 수송층, 전자 수송 층으로 한 소자가 가장 휘도가 우수한 것을 알 수 있었다. 또한 red (europium complex), green (terbium complex), 그리고 blue (TPD) 색깔을 나타내는 유기 재료를 사용하여 한 소자에서 백색 소자를 제작하여 cyclic voltametric방법을 이용하여 각 유기 물질들의 에너지 준위를 조사하여, 각각의 소자들을 에너지 밴드 다이어그램(energy band diagram)으로 자세히 설명하였다.