• Maxillofacial Plastic and Reconstructive Surgery
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• 제17권4호
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• pp.407-414
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• 1995

The information concerning epithelial dysplasia of the oral cavity has been relatively little published. Of the histolgic grades, most of the cases were classified as moderate and severe category. Their ages ranged from 27 to 78 years(mean 57 years). The developmental incidence by sex was superior in male by ratio of 6 : 1. Epithelial lesions were located in the buccal mucosa, Floor of the mouth, the gingiva and the tongue. It is generally believed with a few exceptions that mild degree of epithelial dysplasia do not indicate any great danger for the patient. But severs dysplasia indicates that there is a very considerable risR of malignant transformation. Surgical excision is the effective method of controlling epithelial dysplasia. The authors investigated 7 cases of epithelial dysplasia histopathologically, 2 patients of them had malignant transformation. We discuss the clinical feature, treatment, prognosis, and histopatholgic analysis with literature reviews.

• 한국환경성돌연변이발암원학회지
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• 제19권1호
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• pp.20-27
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• 1999

In order to know the inhibitory effect of magnesium carbonate(MgCO3) on cytotoxicity, DNA damage, mutagenicity, and cell transforming ability of nickel subsulfide, the inhibition of cell proliferation, DNA-protein crosslinks formation (DPC), HGPRT point mutation, and cell transformation were evaluated. Nickel subsulfide(Ni3S2) and magnesium carbonate as insoluble compounds were used for this study. BALB/3T3 cell, CHO-K1 cell, and C3H10T1/2 cell were used in this experiment. Exposure concentration of nickel subsulfide was 1 $\mu\textrm{g}$/ml. The concentrations of magnesium carbonate in this study were 0.6 $\mu\textrm{g}$/ml, 1.2 $\mu\textrm{g}$/ml, 2.4 $\mu\textrm{g}$/ml and the molar ratio of magnesium to nickel when exposed simultanously were 0.5, 1.0 and 2.0 respectively. The results were as follows; 1. Magnesium carbonate reduced the inhibitory effect of nickel subsulfide on cell proliferation. 2. Magnesium carbonate also reduced the effect of nickel subsulfide on DNA-protein crosslinks formation. 3. HGPRT point mutagenicity of nickel subsulfide was reduced when magnesium carbonate treated simultaneously. 4. Magnesium carbonate reduced cell transforming ability of nickel subsulfide. Conclusively, nickel subsulfide showed cytotoxicity, cell transforming ability, and mutagenicity strongly and magnesium carbonate may have protective roles in these nickel effects.

• 수산해양기술연구
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• 제25권3호
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• pp.137-142
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• 1989

본 논문에서는 연속시간계의 설계 문제에 있어, 연속계의 설계방법 그대로서는 설계 불가능한 하나의 문제, 즉, 복소좌반 평면상의 어떤 지정한 폐영역내의 극배치 문제를 쌍선형변환법을 이용해서 해결하는 하나의 설계방법을 제안했다. 실제적인 시스템 설계의 경우, 폐루우프 계의 특성근을 정확히 지정된 위치에 배치하여야만 할 경우는 드물고, 대개의 경우, 어떤 희망하는 영역내에 배치하면 충분하다. 특히 구체적으로 극을 지정하는 지침에 결핍되어 있을 경우나, 폐루우푸 계의 특성인 속응성, 진동특성, 안정도 등을 고려할 경우, 그 극을 지정 위치에 배치하기보다도 어떤 지정한 영역내에 배치하는 쪽이 유효하다고 할 수 있으므로, 다변수제어계의 설계 문제에 있어, 그 가치가 크다고 할 수 있다

• Corrosion Science and Technology
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• 제19권3호
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• pp.146-155
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• 2020

To elucidate the effect of heat inputs on phase transformation and resistance to intergranular corrosion of F316 austenitic stainless steel (ASS), thermodynamic calculations of each phase and time-temperature-transformation diagram were conducted using JMaPro simulation software, oxalic acid etch test, double-loop electrochemical potentiokinetic reactivation test (DL-EPR), field emission scanning electron microscopy with energy dispersive spectroscopy, and transmission electron microscopy analyses of Cr carbide (Cr₂₃C₆), austenite phase and ferrite phase. F316 ASS containing a relatively low C content of 0.043 wt% showed a slightly sensitized microstructure (acceptably dual structure) due to a small amount of Cr carbide precipitated at heat affected zone irrespective of heat inputs. Based on results of DL-EPR test, although heat input was increased, the ratio of I_r to I_a was only increased very slightly due to a slight sensitization. Therefore, heat inputs have little influences on resistance to intergranular corrosion of F316 austenitic stainless steel containing 0.043 wt% C.

• 한국해안해양공학회지
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• 제15권1호
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• pp.51-58
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• 2003

본 연구에서 선형파 이론을 사용하여 파랑변형을 예측할 경우 소멸파 성분의 역학적인 크기를 정량화 하는 작업을 하였다. 두 계단 위로 파랑이 전파하는 경우 고유함수 전개법을 사용하여 반사파와 통과파의 진폭을 진행파와 소멸파 성분 별로 구한 다음 진행파 대비 소멸파 에너지의 중요성이 크게 나타나는 조건을 찾아보았다. 그 결과 앞 계단에서의 상대수심이 k$_1$h$_1$＝0.11$\pi$이고.수심의 비 h$_2$/h$_1$이 0에 가까울 때 소멸파 에너지가 가장 크게 나타남을 알 수 있었다.

• Journal of Korean Neurosurgical Society
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• 제64권5호
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• pp.763-775
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• 2021

Objective : Hemorrhagic transformation (HT) can be occurred after acute cerebral infarction. HT can worse symptoms in severe cases and adversely affect long-term prognosis. As bone and vascular smooth muscle are composed of type 1 collagen, we aimed to identify a potential relationship between bone mineral density (BMD) and HT after acute cardioembolic stroke. Methods : As an indicator of BMD, we used mean frontal skull Hounsfield unit (HU) values on brain computed tomography (CT). Multivariative hazard ratios were calculated using Cox regression analysis to identify whether the osteoporotic condition was an independent predictor of HT after acute cardioembolic stroke. Results : This 11-year analysis enrolled 506 patients who diagnosed as acute cardioembolic infarction. The first tertile of skull HU value was an independent predictor of HT development compared to the third tertile (hazard ratio, 2.12; 95% confidence interval, 1.13-3.98; p=0.020). We observed no interactions between age and skull HU with respect to HT statistically. Conclusion : The results of this study revealed an association between osteoporotic conditions and HT development after acute cardioembolic stroke. A convenient method to measure the cancellous bone HU value of the frontal skull using brain CT images may be useful for predicting HT in patients with acute cerebral infarction.

• 전기학회논문지P
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• 제57권1호
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• pp.1-5
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• 2008

The output voltage value of AC high voltage source has been usually obtained by multiplying low voltage value measured at both terminals of low voltage resistor by the dividing ratio of the high voltage capacitive divider. From the dividing ratio determined of each 200 kV capacitive divider, we have developed step-up method for measuring the output voltage up to 400 kV using two same type of 200 kV capacitive dividers connected in series. The theoretical dividing ratio of 400 kV capacitive dividers connected in series coincides with that of manufacturer's certification within measurement uncertainty. Thus, this developed step-up method makes it possible to extend the range of output voltage from 200 kV to 400 kV. Furthermore, The dividing ratio of divider under test obtained using this step-up method is consistent with that obtained using one 200 kV high voltage divider within corresponding uncertainties.

• Journal of Welding and Joining
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• 제13권2호
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• pp.60-67
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• 1995

The factors affecting on the fatigue strength of spot_welded specimens have been studied. The influence of initial overloads on the fatigue life of spot_welded tensile_shear specimens is investigated by considering fatigue crack initiation and crack propagation. The change of strain range and the influence of initial overload are correlated on the basis ol strain results. The results of this study are as follows. l) The initial absolute strain range decreased with initial overloads increase, and absolute strain range decreased before transformation of waveform of strain, but increased after transformation of waveform of strain. 2) In case of subsequent point of inflection of offset strain, the increment of this strain decreased with initial overload increase. 3) As initial overloads increase, the deformation behavior of spot welded parts is restricted after overloading.

• The Korean Journal of Ceramics
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• 제1권1호
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• pp.45-54
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• 1995

Four kinds of silicon nitride based ceramic materials have been hot pressed. Effect of the sintering additives on the phase transformation, microstructural development and mechanical properties was investigated. While sintering under the same condition a big difference among the microstructures of the specimens, they appeared alike if sintered to have a similiar $\alpha$-$\beta$ phase ratio. The specimen of the stoichiometric $\alpha$-$\beta$ sialon composition showed very limited amount of the intergranular glassy phase and a significant degree of the residual stress. It exhibited almost no strength degradation up to $1300^{\circ}C$, and the strength of the specimen degraded more as its composition deviated from the stoichiometry.

• 한국인쇄학회지
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• 제20권1호
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• pp.28-44
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• 2002

Wavelet transformation in image compression is to offer higher image compressibility and high-quality by quantization and entropy encoding. More image quality is good that reconstructed image by wavelet calculation than acquire cosine transform. Therefore, wavelet itself is function if it is wavelet's feature, in this function, do processing applying difference scale and resolution. That is, this is not that fixed resolution has been decided like existent compression way, when it regulated scale, damage goes in pixel and picture looks like break without giving damage entirely in reflex even if magnify or curtail Decoding. Therefore, this paper is in Image that using new wavelet application compression way research that see applies comparing In each image noted this time compressing step by step with circle image compression efficiency recognize. Also, estimated quality pass through by printing of compressed image, investigated compression ratio of most suitable that get print of high quality and elevation of transmission speed.