• 콘크리트학회논문집
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• 제11권3호
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• pp.13-21
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• 1999

Recently, many strengthening methods are developed to repair damaged structures, especially, steel plate or carbon fiber sheet bonding methods are widely used. For the bonding methods, the strengthening materials are bonded when the original structure is under loading, with causes the difference of initial stresses between original member and bonded material. However, current design method or theory, which mostly depends on ultimately strength design, cannot account the difference of initial stresses between members, and it disregards the reduction of nominal strength. In this study, a new strengthening design theory and program which can account the difference of initial stresses are developed, and applied to the case when a structure in service is repaired. In order to verify the validity of the theory and the program, a test result is referred and compare with the results and it is showed that the calculated values are almost same as the referred data and finally proved that the program is reliable. The results showed that the amount of strengthening material depends on the status of damages of structure, and the nominal strength is reduced depending on the degree of damages.

• 콘크리트학회논문집
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• 제11권3호
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• pp.35-45
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• 1999

Recently, many strengthening methods are developed to repair damaged structures, especially, steel plate or carbon fiber sheet bonding methods are widely used. For the bonding methods, the strengthening materials are bonded when the original structure is under loading, which causes difference of initial stresses between original member and bonded material. However, current design method or theory, which mostly depends on ultimately strength design, cannot account the difference of initial stresses between members, and it disregards the reduction of nominal strength. In this study, a new strengthening design theory and program which can account the difference of initial stresses are developed, and applied to the case when a structure in service is repaired. In order to verify the validity of the theory and the program, a test result is referred and compared with the results and it is showed that the calculated values are almost same as the referred data and finally proved that the program is reliable. The results showed that the amount of strengthening material depends on the status of damages of structure, and the nominal strength is reduced depending on the degree of damages.

• 대한수학회지
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• 제44권4호
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• pp.787-797
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• 2007

In this paper, the following fourth-order rational difference equation $$x_{n+1}=\frac{{x_n^b}+x_n-2x_{n-3}^b+a}{{x_n^bx_{n-2}+x_{n-3}^b+a}$$, n=0, 1, 2,..., where a, b ${\in}$ [0, ${\infty}$) and the initial values $X_{-3},\;X_{-2},\;X_{-1},\;X_0\;{\in}\;(0,\;{\infty})$, is considered and the rule of its trajectory structure is described clearly out. Mainly, the lengths of positive and negative semicycles of its nontrivial solutions are found to occur periodically with prime period 15. The rule is $1^+,\;1^-,\;1^+,\;4^-,\;3^+,\;1^-,\;2^+,\;2^-$ in a period, by which the positive equilibrium point of the equation is verified to be globally asymptotically stable.

• 통합자연과학논문집
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• 제13권4호
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• pp.147-151
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• 2020

In this paper, we propose a method to detect concept drift by applying Convolutional Neural Network (CNN) in a data stream environment. Since the conventional method compares only the final output value of the CNN and detects it as a concept drift if there is a difference, there is a problem in that the actual input value of the data stream reacts sensitively even if there is no significant difference and is incorrectly detected as a concept drift. Therefore, in this paper, in order to reduce such errors, not only the output value of CNN but also the probability vector are used. First, the data entered into the data stream is patterned to learn from the neural network model, and the difference between the output value and probability vector of the current data and the historical data of these learned neural network models is compared to detect the concept drift. The proposed method confirmed that only CNN output values could be used to reduce detection errors compared to how concept drift were detected.

• 대한안전경영과학회지
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• 제23권4호
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• pp.43-48
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• 2021

In this study, the experiment was conducted on a fire door(W × H = 0.98 m × 2.19 m) installed on the vestibule. The effective leakage area for each opening angles and closing forces derived from the impulse-momentum equation was compared and analyzed with the experimental results. As a result of the experiment, the major factors affecting the door closing forces were the pressure difference and the area of the door. The difference of door closing forces between measured and calculated values by the impulse-momentum equation showed a deviation of less than ±15% at the opening angles of 5°to 10°. At the door opening angle of 2.5°, the dynamic pressure was much higher than the measured static pressure, and this pressure difference is estimated to be air resistance acting to prevent the door from being completely closed.

• 대한수학회지
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• 제59권6호
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• pp.1103-1137
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• 2022

Our motivation in this note is to find equal hyperharmonic numbers of different orders. In particular, we deal with the integerness property of the difference of hyperharmonic numbers. Inspired by finiteness results from arithmetic geometry, we see that, under some extra assumption, there are only finitely many pairs of orders for two hyperharmonic numbers of fixed indices to have a certain rational difference. Moreover, using analytic techniques, we get that almost all differences are not integers. On the contrary, we also obtain that there are infinitely many order values where the corresponding differences are integers.

• ETRI Journal
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• 제45권4호
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• pp.704-712
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• 2023

This paper presents a flexible finite-difference technique for analyzing the nonuniform guiding structures. Because the voltage and current variations along the nonuniform structure differ for each segment, this work considers the adaptable discretization steps. This technique increases the accuracy of the final response. Moreover, by applying the singular value decomposition and discarding the nonprincipal singular values, an optimal lower rank approximation of the discretization matrix is obtained. The computational cost of the introduced method is significantly reduced using the optimal discretization matrix. Also, the proposed method can be extended to the nonuniform waveguides. The technique is verified by analyzing several practical transmission lines and waveguides with nonuniform profiles.

• 한국환경보건학회지
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• 제7권1호
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• pp.21-31
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• 1981

This survey was carried out to investigate the temperature, pH value, nitrogen (ammonia, nitrite, nitrate), turbidity, color, chloride ion, $KMnO_4$ consumed, and hardness as chemical analysis of the tap water in Seoul city area during the period from September to Octobor, 1979, and to observe the differences among the values by the distance from the water purification plant and by the district supplied tap water from-the each water purification plant. The results obtained were as follows: 1) An average of the water temperature was $19.8\pm 0.2\circ$C. 2) An average of pH was $7.18\pm 0.02$. The difference among each district was statistically significant (p<0.01), but it was not observed among each distance. 3) An average of turbidity was $1.25\pm 0.12$ ppm. The difference among each district was highly significant (p<0.01), respectively, but not among each distance. 4) An average of color was $1.43\pm 0.16$ ppm, and there were statistically significant differences by the distance and by the district (p<0.01). 5) An average of ammonia nitrogen was $0.022\pm 0.005$ ppm. The differences among each distance, and district were statistically significant (P<0.01). 6) An average of nitrite nitrogen was $0.0050\pm 0.0013$ ppm, and the difference among each distance was highly significant (p<0.01), respectively, and each district showed statistical significance (p<0.01). 7) An average of nitrate nitrogen was $0.82\pm 0.08$ ppm. The difference among each district was significant (p<0.05), and each distance showed high significance (p<0.01). 8) An average of $KMnO_4$ consumed was $3.73\pm 0.16$ ppm, and the difference among each district was significant (p<0.05), but it was not observed among each distance. 9) An average of chloride ion was $8.56\pm 0.28$ ppm, and the difference among each district was higly significant (p<0.01), respectively, but it was not observed among each distance. 10) An average of hardness was $40.69\pm 1.17$ ppm, and there was statistically significant difference by each district (P<0.01), but not by distance. 11) The interrelation between temperature and pH of the tap water revealed the negative correlation from the coefficient of it as showed r=-0.6073 and p<0.01. 12) Except water temperature, there were negative correlationships between pH and other water qualities. 13) Correlation coefficients of $KMnO_4$ comsumed and ammonia nitrogen, nitrite nitrogen were statistically significant but that of $KMnO_4$ consumed and nitrate nitrogen showed no statistical correlationship. 14) Ammonia nitrogen seems to have high correlationship with nitrite nitrogen(r= +0.6669), but not with nitrate nitrogen. 15) Nitrate nitrogen seems to have statistically significant correlationship with nitrite nitrogen (r=+0.4959), but not with ammonia nitrogen. 16) The interrelation between chloride ion and hardness of the tap water revealed positive correlation from the coefficient of it as showed as r=+0.4888 and p<0.01.

• 한국안광학회지
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• 제19권2호
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• pp.231-237
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• 2014

목적: 자동굴절력계의 굴절력 값과 포롭터를 이용한 안경처방 굴절력 값에서, 굴절값 차이의 대소가 나타나는 조건을 연구하였다. 방법: 자동굴절력계(SR-7000)와 자동포롭터(AV-9000)를 이용하여 안질환이 없고, 굴절 이상으로 근용안경을 착용하는 30명을 대상으로 총 60안을 검사 하였다. 검사자에 기인한 굴절력 처방값의 변화를 방지하기 위하여, 2명의 검사자가 동일한 검사 조건에서 피검사자의 눈을 측정하였다. 결과: 통계적으로 2명의 검사자의 굴절력 처방값은 유의할만한 차이가 없었다. 대부분의 측정값에서 포롭터를 이용한 안경처방 굴절력 값이 자동굴절력계를 통해 측정된 굴절력 값보다 작게 측정되었다. 근시에서 (-)구면 굴절력 값이 클수록 자동굴절력계의 측정값과 자동포롭터 처방값 간의 차이가 증가하는 현상은 찾아 볼 수 있었다. 근시성 난시안에서 난시도수의 구간별로 결과를 분석하였다. 난시도수가 증가할수록 자동굴절력계와 자동포롭터 값 사이의 차이는 적어지는 경향을 확인할 수 있었다. 결론: 2명의 검사자의 처방값 간의 차이는 없었다. 자동굴절력계의 굴절력 값과 포롭터를 이용한 안경처방 굴절력 값 차이는 근시나 근시성 난시의 경우 피검사자의 굴절 이상도에 대략 비례한다. 피검사자의 교정 렌즈의 굴절력이 클수록 굴절력 차이가 증가하므로, 교정 렌즈 처방 시 주의가 요구된다.

• 한국연초학회지
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• 제18권1호
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• pp.5-11
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• 1996

Field experiment was conducted to get the basic information about the difference in color and plastid pigments at the different stage of harvest of flue-cured tobacco cultivated in paddy field, and compared to upland ones. All tested crops were primed in lots of 3 to 4 at each priming, beginning at the bottom of the plant. Leaf pigments and chromatic values of tobacco leaves were determined in samples collected at weekly intervals, and according to analyses obtained from 4 stalk positions. By the degree of maturity, leaves harvested were separated with visual characters into four classes of immature, mature, ripe and mellow. regardless of stalk position, chlorophyll contents was higher in the order of immature > mature > ripe > mellow, respectively. In fresh leaves, chlorophyll levels was higher with ascending stalk position. chlorophyll a and b in cured leaves were less than 10% of the amount present at harvest, and it was estimated that maturity condition also influenced the rates of degradation of plastid pigments. Fully mature leaves of upland diverted from paddy field showed slightly higher in chlorophyll contents than in those of upland tobacco ones but somewhat lowered in $L^*$ and $b^*$ values, and there was no difference in $a^*$ value.