• 대한화학회지
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• 제34권6호
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• pp.517-526
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• 1990

D-glucitol hexaacetate 와 xylitol pentaacetate의 결정구조를 단결정 X-선 회절법으로 연구하였다. D-glucitol hexaacetate 는 공간군 P2$_1$, 단위세포 상수는 a = 10.275 (2), b = 8.363 (1), c = 12.560 (5) $\AA$, $\beta$= 95.97 $(2)^{\circ}$; Z = 2이고, xylitol pentaacetate는 공간군이 P2$_1$/C이고, a = 18.126 (1), b = 11.422 (2), c = 8.649 (1) $\AA$, $\beta$ = 95.03 $(1)^{\circ}$이며 Z = 4이다. 회절세기는 diffractomerer로 얻었고, 분자구조는 직접법으로 밝혔으며, 최소자승법으로 정밀화하였다. 두 분자에 결쳐 결합의 평균길이는 C($sp^3)-C(sp^3$)가 1.514 (10), C($sp^3)-O: 1.444 (6),\; C(sp^2)-O: 1.347 (9),\; C(sp^2)=O: 1.197 (6),\; C(sp^2)-C(sp^3): 1.479(9){\AA}$이고, 평균 결합각도는 C($sp^3)-C(sp^3)-C(sp^3): 114.6 (17),\; O-C(sp^3)-C(sp^3): 109.4 (23),\; C(sp^2)-O-C(sp^3): 117.4 (6),\; O=C(sp^2)-O: 122.6 (6),\; C(sp^3)-C(sp^2)-O: 111.8 (7), C(sp^3)-C(sp^2)=O: 125.5 (4)${\circ}$이다. 두 분자내의 탄소 사슬들은 extended zigzag chain으로 되어 있어 D-glucitol과 xylitol 분자들의 conformation과는 다르다. Acetate group들의 각 원자들은 모두 한 평편상에 놓여있다.

• 한국진공학회지
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• 제10권1호
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• pp.16-21
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• 2001

4원 화합물 반도체인 $Ag_2CdSnSe_4$ 및 $Ag_2CdSnSe_4$:$CO^{2+}$ 단결정을 화학수송법으로 성장시켜 광학적 특성을 조사하였다. 성장된 결정들은 wurtzite 결정구조로서 격자상수는 각각 a = 4.357 $\AA$, c = 7.380 $\AA$($Ag_2CdSnSe_4$:$CO^{2+}$)이었다. 298k에서의 광 흡수 측정으로부터 구한 에너지 띠 간격은 순수한 $Ag_2$CdSnSe의 경우 1.21eV, cobalt 불순물로 첨가한 $Ag_2CdSnSe_4$의 경우 1.02ev이었으며, cobalt를 불순물로 첨가함에 따라 190meV의 에너지 띠 간격의 감소를 보였다. $Ag_2CdSnSe_4$ 결정의 광 흡수 스펙트럼에서 4개의 흡수 피크들을 관측하였으며, 이들 피크 들은 $T_d$결정장내에서 스핀 - 궤도결합효과에 의한 $Co^{2+}$ 이온의 분리된 준위사이의 전자전이에 의한 것으로 설명되었다.

• 대한치과보철학회지
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• 제19권1호
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• pp.7-16
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• 1981

The technology of precision attachments has developed at such a pace that from a very few T-shaped attachments and bar attachments from the years 1915 to 1935 since removable bridge utilizing a T-shaped intracoronal attachment was constructed by Dr. Herman E.S. Chayes in 1906. There are now more than 120 models of the most diversified designs, ready made or laboratory fashioned. In 1971, 126 attachments were listed and classified by Mensor in his E M Attachment Selector. This selector consists of five charts giving specifications as to type, vertical dimensions, application, type of resilience, size of movement, type of retention and type of material and alloy. Thus the E M Attachment Selector is a useful guide for dentists to choose the attachment for his patients. But dentists should apply the attachment in each patient's case according to an accurate diagnosis and treatment plan. This paper is a case report of removable partial dentures utilizing CSP, PD and Bar attachment on a patient who needed full mouth reconstruction. Patient has right first, second molar and left first molar on the upper arch and also left first molar, first premolar and right canine on the lower arch. (Fig. 5)All remaining teeth are relatively healthy in their supporting tissues. On upper arch, ring shape CSP attachment was designed on left first molar and modified ring shape CSP attachment was designed on right first and second molar as the direct retainer of the removable partial denture. Full palatal coverage was used as the major connector in this case. (Fig. 23) On lower arch, author first splinted with a fixed bridge between left first molar and second premolar and a splint bar between left second premolar and right canine. (Fig. 11) A lower removable partial denture in which was designed with an Aker clasp on the left first molar and a PD attachment on .the right canine was constructed. (Fig. 17) This denture could get additional support from anterior splint bar. After both removable partial dentures were delivered to the patient (Fig. 26), author evaluated function of the dentures and supporting structures of the abutment teeth by means of clinical and X-ray examinations for eighteen months. According to the examination data author came to the conclusion that the prognosis of this case was excellent.

• 대한화학회지
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• 제18권2호
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• pp.97-109
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• 1974

sulfaguanidine 1수화물의 결정 및 분자구조를 X-선 회절법으로 규명하였다. 결정은 일사축계에 속하며 단위세포내에는 4분자가 있으며 공간군은 $P2_1$/c이다. 단위세포상수는 ${\alpha}=7.57{\pm}0.03,\;b=5.44{\pm}0.02,\;c=24.76{\pm}0.06{\AA},\;{\beta}=91.0{\pm}0.2^{\circ}$이다. 결정구조는 패터슨 함수의 해석과 직접법을 병용하여 밝혀냈다. 원자좌표치는 최소자승법으로 정밀화하였으며 1542개의 독립적인 회절반점에 대한 최종 R값은 0.14이었다. sulfaguanidine분자의 guanidyl기의 질소원자는 2개의 다른 물분자를 매개로 하여 수소결합을 하므로써 다른 분자들의 sulfonyl기의 산소원자에 연결되어 있다. 수소결합 형성에 있어서 물분자는 donor와 acceptor의 역할을 겸하고 있으며 수소결합은 사면체의 방향을 하고 있다. 2차원적인 수소결합에 의하여 연결된 분자들은 (001)면에 평행한 분자층을 형성하고 있다.

• Safety and Health at Work
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• 제8권1호
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• pp.99-104
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• 2017

Background: Workers laboring in steel industries in tropical settings with high ambient temperatures are subjected to thermally stressful environments that can create well-known risks of heat-related illnesses and limit workers' productivity. Methods: A cross-sectional study undertaken in a steel industry in a city nicknamed "Steel City" in Southern India assessed thermal stress by wet bulb globe temperature (WBGT) and level of dehydration from urine color and urine specific gravity. A structured questionnaire captured self-reported heat-related health symptoms of workers. Results: Some 90% WBGT measurements were higher than recommended threshold limit values ($27.2-41.7^{\circ}C$) for heavy and moderate workloads and radiational heat from processes were very high in blooming-mill/coke-oven ($67.6^{\circ}C$ globe temperature). Widespread heat-related health concerns were prevalent among workers, including excessive sweating, fatigue, and tiredness reported by 50% workers. Productivity loss was significantly reported high in workers with direct heat exposures compared to those with indirect heat exposures ($x^2=26.1258$, degrees of freedom = 1, p < 0.001). Change in urine color was 7.4 times higher among workers exposed to WBGTs above threshold limit values (TLVs). Conclusion: Preliminary evidence shows that high heat exposures and heavy workload adversely affect the workers' health and reduce their work capacities. Health and productivity risks in developing tropical country work settings can be further aggravated by the predicted temperature rise due to climate change, without appropriate interventions. Apart from industries enhancing welfare facilities and designing control interventions, further physiological studies with a seasonal approach and interventional studies are needed to strengthen evidence for developing comprehensive policies to protect workers employed in high heat industries.

• 대한임상검사과학회지
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• 제41권4호
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• pp.167-172
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• 2009

Methotrexate (MTX) in one of the antineoplastic drug and it is known to effective to management of acute lymphoblastic leukemia in children, management of choriocarcinoma and related trophoblastic tumors in women, management of carcinomas of the breast, tongue, pharynx, and tests, maintenance of remission in leukemia and treatment of serve, debilitating psoriasis. Intermediate to high-dose methotrexate administration followed by leucovorin rescue is effective in treatment of carcinoma of the lung and osteogenic sarcoma. Intrathecal administration is effective in treating meningeal leukemia or lymphoma. There are FPIA (Fluorescence polarization immunoassay) and EMIT (Enzyme multiplied immunotechique) methods that measure for MTX. We evaluated the FPIA and EMIT methods. MTX were measured by Hitachi-7600 P-module using EMIT and FPIA using TDX in the sera 60 patients. The performance characteristics evaluated were, light influence, linearity, comparison with FPIA. Also, precision evaluated were three level controls through put following CLSI evaluation protocols (EP10-A). When the MTX value of $4.16{\pm}5.78{\mu}{\mu}mol/L$ (mean, SD) by the Hitachi-7600 P-module was compared with that of $4.05{\pm}5.47{\mu}{\mu}mol/L$ by FPIA, coefficients of correlation of 0.988 was obtained. The regression equation was Y (Hitachi-7600 P-module) = 0.9408 x (FPIA) + 0.1316 (r=0.9885, n=60). CVs of MTX measured by Hitachi 7600 P-module was 6.78% at $0.33{\mu}{\mu}mol/L$, 0.96% at $1.16{\mu}{\mu}mol/L$, and 0.96% at $8.04{\mu}{\mu}mol/L$. The precision was excellent in each group. The linearity was acceptable. We evaluated that MTX is light-sensitive on prolonged exposure to direct sunlight. Comparing with the FPIA using TDX, the Hitachi-7600 P-module using EMIT showed good coefficient of correlation and precision. Therefore the Hitachi-7600 P-module can replace the FPIA for quantitative analysis of MTX.

• 한국방사선학회논문지
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• 제9권7호
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• pp.467-471
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• 2015

본 연구에서는 L-tube insertion 환자의 흉부 AP 검사 시 tube tip이 환자의 자세나 방사선 조사각에 의해 왜곡되는 정도를 파악하고 정확한 임상정보를 제공하기 위해 검사 시 정확한 tube 각도를 유지하여 영상의 질을 높이고자 하는데 있다. 실험 장비로 SHIMADZU사의 ELMO-T6S를 사용하였으며, Chest phantom의 표면에 1 mm 간격의 눈금격자를 부착한 L-tube를 부착하여 실험을 하였다. 실험영상의 영상 획득 조건은 90 kVp, 4 mAs, SSD 120 cm로 하여 영상을 획득하였다. Phantom position은 table에서 supine, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$로 변화시키고 각 position마다 Head 방향과 Feet 방향으로 수직, ${\pm}5^{\circ}$, ${\pm}10^{\circ}$, ${\pm}15^{\circ}$ 촬영을 하여 영상을 획득하였다. 본 실험 결과로 L-tube tip의 위치는 환자의 자세와 방사선 입사각에 따라 달라지며 환자의 position이 30, 45, $60^{\circ}$일 때 보다 supine 일 때 tip의 위치변화가 적은 것으로 나타났다. 흉부 방사선 검사를 통해 L-tube tip의 정확한 위치를 보고자 할 때 잘못 된 입사각에 의한 영상의 왜곡이 발생하지 않도록 환자의 자세나 입사각을 조정해야 하며, 해당 시술을 확인하는데 정확한 평가 지표로 이용될 수 있도록 임상에서 업무를 수행하는 방사선사들의 세심한 노력이 필요할 것으로 사료된다.

• 한국항해항만학회지
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• 제27권4호
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• pp.443-447
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• 2003

본 논문에서는 $0.2\mu\textrm{m}$ GaAs MODFET(modulation doped FET)를 이용하여 제작한 위성방송수신용 고성능 다운컨버터 MMIC에 관해서 보고한다. GaAs 화합물 반도체 기판상에 제작된 본 논문의 고집적 다운컨버터 MMIC는 싱글 밸런스 믹서, IF증폭기, 액티브형 버룬, 그리고 국부 발진기 주파수(LO) 신호의 누설전력 억제용 필터까지 한 칩에 내장하고 있다. 저잡음특성을 실현하기 위해서, 믹서의 소스부에 소스인덕터가 접속된 소스인덕터 피드백 회로형태의 믹서를 이용하였으며, 그 결과 잡음지수 4.8 dB의 초저잡음 다운컨버터 MMIC가 실현되었다. 이는 종래의 위성방송 수신용 다운컨버터 MMIC의 잡음지수보다 3 dB정도 낮은 수치이다. 그리고, 소비전력을 줄이기 위해 믹서에 대해서 저 LO입력 전력 설계를 수행하였고, 그 결과 믹서의 LO신호 입력부에 위치하는 LO 증폭기가 불필요하게 되었다. 이로인해 본 논문의 다운컨버터 MMIC에 대해서 175 mW(동작전압:5V, 소비전류:35mA)의 저소비전력 특성을 얻을 수 있었으며, 이는 종래의 위성방송 수신용 다운컨버터 MMIC의 소비전력의 70%에 해당한다. 더욱이, IF신호 출력단에서의 LO신호 누설전력을 억제하기 위해서, 스파이럴 인덕터 필터가 본 논문의 MMIC에 내장되었다. 그리고, 다운컨버터 MMIC 칩의 면적을 줄이기 위해, 믹서의 입력부의 X밴드 입력정합회로로서 MMIC 패키지 내부의 본딩 와이어를 이용하였다. 그 결과, $0.84{\times}0.9\textrm{mm}^2$의 초소형 MMIC가 제작되었다. 본 논문의 MMIC 칩 면적은 종래의 위성방송 수신용 MMIC의 50%이하이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.99-99
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• 2013

In this talk, I will present two research works in progress, which are: i) mapping of piezoelectric polarization and associated charge density distribution in the heteroepitaxial InGaN/GaN multi-quantum well (MQW) structure of a light emitting diode (LED) by using inline electron holography and ii) in-situ observation of the polarization switching process of an ferroelectric Pb(Zr1-x,Tix)O3 (PZT) thin film capacitor under an applied electric field in transmission electron microscope (TEM). In the first part, I will show that strain as well as total charge density distributions can be mapped quantitatively across all the functional layers constituting a LED, including n-type GaN, InGaN/GaN MQWs, and p-type GaN with sub-nm spatial resolution (~0.8 nm) by using inline electron holography. The experimentally obtained strain maps were verified by comparison with finite element method simulations and confirmed that not only InGaN QWs (2.5 nm in thickness) but also GaN QBs (10 nm in thickness) in the MQW structure are strained complementary to accommodate the lattice misfit strain. Because of this complementary strain of GaN QBs, the strain gradient and also (piezoelectric) polarization gradient across the MQW changes more steeply than expected, resulting in more polarization charge density at the MQW interfaces than the typically expected value from the spontaneous polarization mismatch alone. By quantitative and comparative analysis of the total charge density map with the polarization charge map, we can clarify what extent of the polarization charges are compensated by the electrons supplied from the n-doped GaN QBs. Comparison with the simulated energy band diagrams with various screening parameters show that only 60% of the net polarization charges are compensated by the electrons from the GaN QBs, which results in the internal field of ~2.0 MV cm-1 across each pair of GaN/InGaN of the MQW structure. In the second part of my talk, I will present in-situ observations of the polarization switching process of a planar Ni/PZT/SrRuO3 capacitor using TEM. We observed the preferential, but asymmetric, nucleation and forward growth of switched c-domains at the PZT/electrode interfaces arising from the built-in electric field beneath each interface. The subsequent sideways growth was inhibited by the depolarization field due to the imperfect charge compensation at the counter electrode and preexisting a-domain walls, leading to asymmetric switching. It was found that the preexisting a-domains split into fine a- and c-domains constituting a $90^{\circ}$ stripe domain pattern during the $180^{\circ}$ polarization switching process, revealing that these domains also actively participated in the out-of-plane polarization switching. The real-time observations uncovered the origin of the switching asymmetry and further clarified the importance of charged domain walls and the interfaces with electrodes in the ferroelectric switching processes.

• Molecules and Cells
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• 제37권3호
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• pp.264-269
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• 2014

The molecular interaction between tumor suppressor p53 and the anti-apoptotic Bcl-2 family proteins plays an essential role in the transcription-independent apoptotic pathway of p53. In this study, we investigated the binding of p53 DNA-binding domain (p53DBD) with the anti-apoptotic Bcl-2 family proteins, Bcl-w, Mcl-1, and Bcl-2, using GST pull-down assay and NMR spectroscopy. The GST pull-down assays and NMR experiments demonstrated the direct binding of the p53DBD with Bcl-w, Mcl-1, and Bcl-2. Further, NMR chemical shift perturbation data showed that Bcl-w and Mcl-1 bind to the positively charged DNA-binding surface of p53DBD. Noticeably, the refined structural models of the complexes between p53DBD and Bcl-w, Mcl-1, and Bcl-2 showed that the binding mode of p53DBD is highly conserved among the anti-apoptotic Bcl-2 family proteins. Furthermore, the chemical shift perturbations on Bcl-w, Mcl-1, and Bcl-2 induced by p53DBD binding occurred not only at the p53DBD-binding acidic region but also at the BH3 peptide-binding pocket, which suggests an allosteric conformational change similar to that observed in Bcl-$X_L$. Taken altogether, our results revealed a structural basis for a conserved binding mechanism between p53DBD and the anti-apoptotic Bcl-2 family proteins, which shed light on to the molecular understanding of the transcription-independent apoptosis pathway of p53.