• Title, Summary, Keyword: 가역성

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5th Graders' Logical Development through Learning Division with Decimals (5학년 아동의 소수 나눗셈 원리 이해에 관한 연구)

  • Lee, Jong-Euk
    • School Mathematics
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    • v.9 no.1
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    • pp.99-117
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    • 2007
  • In this paper it is discussed how children develop their logical reasoning beyond difficulties in the process of making sense of division with decimals in the classroom setting. When we consider the gap between mathematics at elementary and secondary levels, and given the logical nature of mathematics at the latter levels, it can be seen as important that the aspects of children's logical development in the upper grades in elementary school should be clarified. This study focuses on the teaching and learning of division with decimals in a 5th grade classroom, because it is well known to be difficult for children to understand the meaning of division with decimals. It is suggested that children begin to conceive division as the relationship between the equivalent expressions at the hypothetical-deductive level detached from the concrete one, and that children's explanation based on a reversibility of reciprocity are effective in overcoming the difficulties related to division with decimals. It enables children to conceive multiplication and division as a system of operations.

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Clinical and Radiological Analysis of Reversible Posterior Leukoencephalopathy Syndrome in Children (소아에서 가역성 후두부 백질 뇌증 증후군의 임상적, 방사선학적 특성에 대한 고찰)

  • Lim, Hae-Ri;Seo, Hye-Eun;Kwon, Sun-Hak
    • Clinical and Experimental Pediatrics
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    • v.50 no.9
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    • pp.901-904
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    • 2007
  • Purpose : Reversible posterior leukoencephalopathy syndrome is a complex disorder with characteristic clinical and radiologic findings that mainly involve the white/gray matter of the parieto-occipital lobes. The purpose of this study was to determine its clinical and radiological characteristics. Methods : A total of 15 pateints were involved in the study. Their medical records and radiological features of brain MRI were retrospectively reviewed and analyzed. Results : Fifteen pateints were involved. (9 males and 5 females). The patients' ages ranged from 2-20 years (mean age : 10 years). The brain MRI revealed fairly symmetric areas of increased T2 signal involving both white and gray matter of parieto-occipital regions. The condition seemed to be associated with cyclosporin A and steroid therapy or a variety of other conditions in which blood pressure rises acutely. Conclusion : Reversible posterior leukoencephalopathy syndrome is a complicated neurological condition, but a better understanding of this complex syndrome may obviate unnecessary investigations and lead to prompt and appropriate management of the associated problems.

Reversible Watermarking based Video Contents Management and Control technique using Biological Organism Model (생물학적 유기체 모델을 이용한 가역 워터마킹 기반 비디오 콘텐츠 관리 및 제어 기법)

  • Jang, Bong-Joo;Lee, Suk-Hwan;Kwon, Ki-Ryong
    • Journal of Korea Multimedia Society
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    • v.16 no.7
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    • pp.841-851
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    • 2013
  • The infectious information hiding system(IIHS) is proposed for secure distribution of high quality video contents by applying optimized watermark embedding and detection algorithms to video codecs. And the watermark as infectious information is transmitted while target video is displayed or edited by codecs. This paper proposes a fast and effective reversible watermarking and infectious information generation for IIHS. Our reversible watermarking scheme enables video decoder to control video quality and watermark strength actively for by adding control code and expiration date with the watermark. Also, we designed our scheme with low computational complexity to satisfy it's real-time processing in a video codec, and to prevent time or frame delay during watermark detection and video restoration, we embedded one watermark and one side information within a macro-block. Experimental results verify that our scheme satisfy real-time watermark embedding and detection and watermark error is 0% after reversible watermark detection. Finally, we conform that the quality of restored video contens is almost same with compressed video without watermarking algorithm.

Myocardial viability in acute myocardial infarction: Cardiac MR imaging vs T1 - 201 myocardiac spect

  • 김혜선;박충기;박동우;김용수;김영선;최요원;전석철;서흥석;함창곡
    • Proceedings of the KSMRM Conference
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    • pp.134-134
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    • 2002
  • 목적: 심근경색의 가역성 여부 판단시 cardiac MR imaging(CMRI)와 myocardial SPECT의 정확성을 비교하기 위하여 대상 및 방법: 흉통을 주소로 내원한 환자 중 CMRI와 SPECT를 시행한 17를 대상으로 역행적으로 조사하였다. CMRI는 double and triple inversion recovery image(IR)에서 심벽의 고신호강도, 2D-FIESTA에서 심기능 분석을 조사하였다. 이어 gadopentetate를 주입하여 확산스캔에서 확산결손을 조사하였다. 연속하여 gadopentetate를 더 주입 후 5분 후 지연심근강조영상을 얻어 지연조영증강 유무와 미세혈류 폐쇄를 조사하였다. SPECT는 아데노신으로 stress 스캔을 얻은 후 T1-201을 재주사 후 rest 스캔하여 확산결손과 재분배를 조사하여 가역성을 판단하였다.

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Interpretation of Bronchodilator Response in Patients with Obstructive Airway Disease (폐쇄성 기도 질환자에서 기관지 확장제 반응에 대한 평가)

  • Choi, Hee-Jin;Kim, Ki-Bum;Cho, Young-Bock;Cho, Ihn-Ho;Chung, Jin-Hong;Lee, Kwan-Ho;Lee, Hyun-Woo
    • Tuberculosis and Respiratory Diseases
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    • v.42 no.3
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    • pp.332-341
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    • 1995
  • Background: Measurement of bronchodilator response is necessary to establish reversibility of airflow obstruction that was helpful to estimate the diagnosis, treatment, and prognosis in obstructive airway disease. An useful index should be able to detect the bronchodilator response more sensitively not related with degree of airflow obstruction and also be independent of initial $FEV_1$. Method: Sensitivities of bronchodilator response in each group classified by degree of airflow obstruction in $FEV_1$, FVC, $FEF_{25\sim75%}$, Isovolume $FEF_{25\sim75%}$, sGaw were studied and correlation coefficients were calculated between initial $FEV_1$ and reversibilities expressed as absolute, %initial, % predicted, %possible in $FEV_1$. Result: Sensitivities of bronchodilator response were 61.5% in FVC, Isovolume $FEF_{25\sim75%}$ and sGaw, in severe group, and 56.3% in Isovolume $FEF_{25\sim75%}$ and sGaw, in moderate group, and 62.5% in $FEV_1$ and sGaw and 50.0% in FVC and Isovolume $FEF_{25\sim75%}$, in mild group, and 60.0% in sGaw and 58.0% in Isovolume $FEF_{25\sim75%}$ in total patients. Correlation coefficients between initial $FEV_1$(L) and absolute, % initial, % predicted, % possible were 0.15, -0.22(p<0.05), 0.02, 0.24(p<0.05) and correlation coefficients between initial $FEV_1$(% predicted) and absolute, % initial, % predicted, %possible were 0.06, -0.28(p<0.05), 0.08, 0.39(p<0.05). Conclusion: Volume related parameters were more sensitive index not related with degree of airway obstruction and the change in $FEV_1$ expressed as % predicted was the least dependent on initial $FEV_1$ and reversibilities, expressed as % initial or as % possible(predicted minus initial $FEV_1$)were correlated with initial $FEV_1$.

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Block-based Image Authentication Algorithm using Differential Histogram-based Reversible Watermarking (차이값 히스토그램 기반 가역 워터마킹을 이용한 블록 단위 영상 인증 알고리즘)

  • Yeo, Dong-Gyu;Lee, Hae-Yeoun
    • The KIPS Transactions:PartB
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    • v.18B no.6
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    • pp.355-364
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    • 2011
  • In most applications requiring high-confidential images, reversible watermarking is an effective way to ensure the integrity of images. Many watermarking researches which have been adapted to authenticate contents cannot recover the original image after authentication. However, reversible watermarking inserts the watermark signal into digital contents in such a way that the original contents can be restored without any quality loss while preserving visual quality. To detect malicious tampering, this paper presents a new block-based image authentication algorithm using differential histogram-based reversible watermarking. To generate an authentication code, the DCT-based authentication feature from each image block is extracted and combined with user-specific code. Then, the authentication code is embedded into image itself with reversible watermarking. The image can be authenticated by comparing the extracted code and the newly generated code and restored into the original image. Through experiments using multiple images, we prove that the presented algorithm has achieved over 97% authentication rate with high visual quality and complete reversibility.

Electrochemical Behaviors of Copper-1-(2-Thiazolylazo)-2-naphthol Complex in Acetonitrile (아세토니트릴 용매 중에서 Copper-1-(2-Thiazolylazo)-2-naphthol 착물의 전기화학적 거동)

  • Bae Zun Ung;Lee Heung Lark;Park Tae Myung;Seo Moo Lyong
    • Journal of the Korean Chemical Society
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    • v.35 no.4
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    • pp.405-409
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    • 1991
  • The electrochemical behaviors of copper-1-(2-thiazolylazo)-2-naphthol [Cu(II)-TAN] complex in acetonitrile (AN) solution have been investigated by the use of polarography, controlled potential coulometry and UV-Vis spectroscopy. Cu(II)-TAN complex exhibit three reduction waves at -0.91 V, -1.34 V and -1.65 V vs. S.C.E. in acetonitrile solution containing 5.0 ${\times}\;10^{-3}$M tetraethylammonium perchlorate. Every reduction wave is diffusion controlled. The first reduction wave is considerably reversible and this process is attributed to the formation of anion radical. The second reduction process to the dianion is followed by a chemical reaction producing a complex of hydrazo complex. The third reduction process produce Cu(Hg) amalgam and amine compound.

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Prediction of Improvement of Myocardial Wall Motion after Coronary Artery Bypass Surgery Using Rest T1-201/Dipyridamole Stress Gated Tc-99m-MIBI/24 Hour Delay T1-201 SPECT (휴식기 T1-201/디피리다몰 부하 게이트 Tc-99m-MIBI/24시간 지연 T1-201 SPECT를 이용한 관상동맥 우회로 수술 후 심근벽 운동 호전의 예측)

  • Lee, Dong-Soo;Lee, Won-Woo;Yeo, Jeong-Seok;Kim, Seok-Ki;Kim, Ki-Bong;Chung, June-Key;Lee, Myung-Chul
    • The Korean Journal of Nuclear Medicine
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    • v.32 no.6
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    • pp.497-508
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    • 1998
  • Purpose: Using rest T1-201/dipyridamole stress gated Tc-99m-MIBI/ 24 hour delay T1-201 SPECT, we investigated the predictive values of the markers of the stress-rest reversibility (Rev), T1-201 rest perfusion (Rest), T1-201 24 hour redistribution (Del) and Tc-99m-MIBI gated systolic thickening (Thk) for wall motion improvement after coronary artery bypass surgery. Materials and Methods: In 39 patients (M;F= 34:5, age $58{\pm}8$), preoperative and postoperative (3 months) SPECT were compared. 24 hour delayed SPECT was done in 16 patients having perfusion defects at rest. Perfusion or wall motion was scored from 0 to 3 (0: normal to 3: defect or dyskinesia). Wall motion was abnormal in 142 segments among 585 segments of 99 artery territories which were surgically revascularized. Results: After bypass surgery, ejection fraction increased from $37.8{\pm}9.0%$ to $45.5{\pm}12.3%$ in 22 patients who had decreased ejection fraction preoperatively. Wall motion improved in 103 (72.5%) segments among 142 dysfunctional segments. Positive predictive values (PPV) of Rev, Rest, Del, and Thk were 83%, 76%, 43%, and 69% respectively. Negative predictive values (NPV) of Rev, Rest, Del, and Thk were 48%, 44%, 58%, and 21%, respectively. Rest/gated stress/delay SPECT had PPV of 74% and NPV of 46%. Though univariate logistic regression analysis revealed Rev (p=0.0008) and Rest (p=0.024) as significant predictors, stepwise multivariate test found Rev as the only good predictor (p=0.0008). Conclusion: Among independent predictors obtained by rest T1-201/ stress gated Tc-99m-MIBI/ delayed T1-201 myocardial SPECT for wall motion improvement after bypass surgery, stress-rest reversibility was the single most useful predictor.

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Effects of Perfusion Defect on the Measurement of Left Ventricular Mass, Ventricular Volume and Post-stress Left Ventricular Ejection Fraction in Gated Myocardial Perfusion SPECT (정량적 게이트 심근관류 스펙트 검사에서 관류결손이 좌심근질량 측정과 부하 후 좌심실 용적 및 구혈률에 미치는 영향)

  • Ahn, Byeong-Cheol;Bae, Sun-Keun;Lee, Sang-Woo;Jeong, Sin-Young;Lee, Jae-Tae;Lee, Kyu-Bo
    • The Korean Journal of Nuclear Medicine
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    • v.36 no.6
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    • pp.381-391
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    • 2002
  • Purpose: The presence of perfusion defect may influence the left ventricular mass (LVM) measurement by quantitative gated myocardial perfusion SPECT (QGS), and ischemic myocardium, usually showing perfusion defect may produce post-stress LV dysfunction. This study was aimed to evaluate the effects of extent and reversibility of perfusion defect on the automatic measurement of LVM by QGS and to investigate the effect of reversibility of perfusion defect on post-stress LV dysfunction. Subjects and Methods: Forty-six patients (male/female=34:12, mean age=64years) with perfusion defect on myocardial perfusion SPECT underwent rest and post-stress QGS. Forty patients (87%) showed reversible defect. End-diastolic volume (EDV), end-systolic volume (ESV), LV ejection fraction (EF), and LV myocardial volume were obtained from QGS by AutoQUANT program, and LVM was calculated by multiplying the LV myocardial volume by the specific gravity of myocardium. Results: LVMs measured at rest and post-stress QGS showed good correlation, and higher correlation was founded in the subjects with fixed perfusion defect and with small defect (smaller than 20%). There were no significant differences in EDVs, ESVs and EFs between obtained by rest and post-stress QGS un patients with fixed myocardial defect. Whereas, EF obtained by post-stress QGS was lower than that by rest QGS in patients with reversible defect and 10 (25%) of them showed decreases in EF more than 5% in post-stress QGS, as compared to that of rest QGS. Excellent correlations of EDVs, ESVs, EFs between rest and post-stress QGS were noted. Patients with fixed defect had higher correlation between EDVs, ESVs, EFs than patients with reversible defect. Conclusion: These results suggest that perfusion defect can affect LVM measurement by QGS and patients with reversible defect shows post-stress LV dysfunction more frequently than patients with fixed perfusion defect.