• Title/Summary/Keyword: delta function

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A Study on Fault Characteristics of DFIG in Distribution Systems Based on the PSCAD/EMTDC (PSCAD/EMTDC를 이용한 풍력발전의 배전계통 사고특성에 관한 연구)

  • Son, Joon-Ho;Kim, Byung-Ki;Jeon, Jin-Taek;Rho, Dae-Seok
    • Journal of the Korea Convergence Society
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    • v.2 no.2
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    • pp.47-56
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    • 2011
  • Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.

TRANSLUCENCY OF LIGHT CURED COMPOSITE RESINS DEPENDS ON THICKNESS & ITS INFLUENCE ON COLOR OF RESTORATIONS (광중합복합레진의 두께에 따른 투명도 차이가 수복물의 색상에 미치는 영향)

  • Hwang, In-Nam;Lee, Kwang-Won
    • Restorative Dentistry and Endodontics
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    • v.24 no.4
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    • pp.585-603
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    • 1999
  • Esthetic availabilities used as an esthetic restorative maternals can be determined by the optical coincidence among materials, enamel and dentin. Enamel is highly translucent. That's why esthetic materials need to correspond the close translucency of enamel. But the translucent materials are affected by the background color. So it should be predicted that the color of estorative materials depend on the any thickness and the spectral reflectance of the background on which they are placed. The object of this investigation, under above hypothesis, was to determine and analyze how they affect the final color according to the thickness, translucency and background color (white, black and dentin) fill three commercial light cured composite resins(Charisma, Spectrum TPH and Z100). And correlation was analyzed to find out the possibility of the prediction when using the certain background color and thickness of materials. Followings are the result 1. The I shade of CHA showed the lowest contrast ratio($Co_7$) while the B3 shade of Z100 showed the highest contrast ratio(p<0.05). 2. The value of $L^*$ and $b^*$ on the white and dentin background is increased with decreasing thickness. And there are significant relationships between increasing thickness and each value(R>0.085). But there is a little change of $L^*$ and $b^*$ value on the black background regardless of the thickness(p>0.05). 3. For the $a^*$ value, there was little difference in values as a function of thickness and changed irregularly regardless of thickness in all background. 4. The pattern of increasing value of $L^*$ and $b^*$ with decreasing thickness was similar to the group of white and dentin background. In both dentin one showed lesser change of value. 5. The values of $L^*a^*b^*$ measured on the different background with same thickness showed the recognizable color difference(${\Delta}E^*$>2) when the thickness was below 2.6mm. 6. Contrast ratio was increased with increasing thickness with significant relationship (R>0.9). 7. Spectral reflectance of composite resins that calculated from Kubelka-Munk equation was showed little difference compared with observed value w1th decreasing thickness.

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Usefulness and Limitations of Extreme Value Theory VAR model : The Korean Stock Market (극한치이론을 이용한 VAR 추정치의 유용성과 한계 - 우리나라 주식시장을 중심으로 -)

  • Kim, Kyu-Hyong;Lee, Joon-Haeng
    • The Korean Journal of Financial Management
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    • v.22 no.1
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    • pp.119-146
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    • 2005
  • This study applies extreme value theory to get extreme value-VAR for Korean Stock market and showed the usefulness of the approach. Block maxima model and POT model were used as extreme value models and tested which model was more appropriate through back testing. It was shown that the block maxima model was unstable as the variation of the estimate was very large depending on the confidence level and the magnitude of the estimates depended largely on the block size. This shows that block maxima model was not appropriate for Korean Stock market. On the other hand POT model was relatively stable even though extreme value VAR depended on the selection of the critical value. Back test also showed VAR showed a better result than delta VAR above 97.5% confidence level. POT model performs better the higher the confidence level, which suggests that POT model is useful as a risk management tool especially for VAR estimates with a confidence level higher than 99%. This study picks up the right tail and left tail of the return distribution and estimates the EVT-VAR for each, which reflects the asymmetry of the return distribution of the Korean Stock market.

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Predictive model and quantitative microbial risk assessment of enterohemorrhagic Escherichia coli and Campylobacter jejuni in milk (우유에서 장출혈성 대장균과 캠필로박터균의 행동예측 모델 개발 및 정량적 미생물 위해성 평가 연구)

  • Dong, Jiaming;Min, Kyung Jin;Seo, Kun Ho;Yoon, Ki Sun
    • Korean Journal of Food Science and Technology
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    • v.53 no.5
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    • pp.657-668
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    • 2021
  • We prepared the growth and survival models of enterohemorrhagic Escherichia coli (EHEC) and Campylobacter jejuni in milk as a function of temperature and assessed the microbiological risks associated with the consumption of whole milk. EHEC and C. jejuni were not detected in whole milk (n=195) in the retail market. The minimum growth temperature of EHEC in milk was 7℃. The lag time of EHEC in whole milk was longer than that in skim milk. The survival ability of C. jejuni in milk was better at 4℃ than at 10℃. Lower delta values were observed in whole milk than in skim milk, indicating that C. jejuni survived better in skim milk. The probability of foodborne illness from whole milk consumption was 5.70×10-5 for EHEC and 9.86×10-9 for C. jejuni. Sensitivity analysis results show that the market temperature of EHEC and the dose-response model of C. jejuni are correlated with the probability of foodborne illness.

A Study on the Hull-dimension of 89 ton class Stow-net Vessel with Stern-fishing (89톤급 선미식 안강망어선의 선형치수에 관한 연구)

  • Park, Je-Ung;Lee, Hyeon-Sang
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.33 no.3
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    • pp.159-165
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    • 1997
  • This paper presents the optimum dimension of 89 ton class stow-net vessel with stern-fishing. The model of basic design is developed by using the optimization techniques referring to objective function and numerous constraints as follows; speed, fishing quantity, fishing days, catch per unit effort(CPUE), and weight/ratio of main dimensions, etc. Thus, the basic design of stow-net fishing vessel is built up by using the optimization of the design variables called the economic optimization criteria, and the objective function represents the criterion which is cost benefit ratio(CBR). The main conclusions are as follows. 1. S/W for decision of optimum hull size is developed in 89 ton class stow-net fishing vessel which is constructed with optimization of the design variables called the economic optimization criteria. 2. For optimum ship dimensions in 89 ton class stow-net fishing vessel, the hull dimensions can be obtained in the range of L= 27.3m, B = 6.6m, D = 2.80m, Cb = 0.695, T/D = 0.80, $\Delta$(displacement)=281.7ton with 10 knots.

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A Novel Glycine-Rich Region in Sox4 is a Target for the Proteolytic Cleavage in E. coli (전사활성 인자인 Sox4의 단백질 분해효소에 의한 표적 부위에 관한 연구)

  • 허은혜;최주연;장경희;김인경;임향숙
    • Korean Journal of Microbiology
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    • v.38 no.3
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    • pp.153-161
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    • 2002
  • Sox4, a transcription factor, consists of three functional domains: an HMG-box domain as a DNA binding domain, serine rich region as a transactivation domain and glycine rich region (GRR), an unknown functional domain. Although Sox4 is known to be functionally involved in heart, B-cell and reproductive system development, its physiological function remains to be elucidated. We used pGEX expression system to develop a simple and rapid method for purifying Sox4 protein in suitable forms for biochemical studies of their functions. Unexpectedly, we observed that full-length Sox4 appears to be protease-sensitive during expression and purification in E. coli. To map the protease-sensitive site in Sox4, we generated various constructs with each of functional domains of Sox4 and purified as the GST-Sox4 fusion proteins using glutathione beads. We found that the specific cleavage site for the proteolytic enzyme, which exists in E. coli, is localized within the novel GRR of Sox4. Our study suggest that the GRR of Sox4 may a target for the cellular protease action and this cleavage in the GRR may be involved in regulating physiological function of Sox4. Additionally, our study may provide a useful method for investigating the proteolytic cleavage of the target molecule in E. coli.

The Effects of Perceived Quality Factors on the Customer Loyalty: Focused on the Analysis of Difference between PB and NB (지각된 품질요인이 고객충성도에 미치는 영향: PB와 NB간의 차이분석)

  • Ye, Jong-Suk;Jun, So-Yon
    • Journal of Distribution Research
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    • v.15 no.2
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    • pp.1-34
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    • 2010
  • Introduction As consumers' purchase behavior change into a rational and practical direction, the discount store industry came to have keen competition along with rapid external growth. Therefore as a solution, distribution businesses are concentrating on developing PB(Private Brand) which can realize differentiation and profitability at the same time. And as improvement in customer loyalty beyond customer satisfaction is effective in surviving in an environment with keen competition, PB is being used as a strategic tool to improve customer loyalty. To improve loyalty among PB users, it is necessary to develop PB by examining properties of a customer group, first of all, quality level perceived by consumers should be met to obtain customer satisfaction and customer trust and consequently induce customer loyalty. To provide results of systematic analysis on relations between antecedents influenced perceived quality and variables affecting customer loyalty, this study proposed a research model based on causal relations verified in prior researches and set 16 hypotheses about relations among 9 theoretical variables. Data was collected from 400 adult customers residing in Seoul and the Metropolitan area and using large scale discount stores, among them, 375 copies were analyzed using SPSS 15.0 and Amos 7.0. The findings of the present study followed as; We ascertained that the higher company reputation, brand reputation, product experience and brand familiarity, the higher perceived quality. The study also examined the higher perceived quality, the higher customer satisfaction, customer trust and customer loyalty. The findings showed that the higher customer satisfaction and customer trust, the higher customer loyalty. As for moderating effects between PB and NB in terms of influences of perceived quality factors on perceived quality, we can ascertain that PB was higher than NB in the influences of company reputation on perceived quality while NB was higher than PB in the influences of brand reputation and brand familiarity on perceived quality. These results of empirical analysis will be useful for those concerned to do marketing activities based on a clearer understanding of antecedents and consecutive factors influenced perceived quality. At last, discussions about academical and managerial implications in these results, we suggested the limitations of this study and the future research directions. Research Model and Hypotheses Test After analyzing if antecedent variables having influence on perceived quality shows any difference between PB and NB in terms of their influences on them, the relation between variables that have influence on customer loyalty was determined as Figure 1. We established 16 hypotheses to test and hypotheses are as follows; H1-1: Perceived price has a positive effect on perceived quality. H1-2: It is expected that PB and NB would have different influence in terms of perceived price on perceived quality. H2-1: Company reputation has a positive effect on perceived quality. H2-2: It is expected that PB and NB would have different influence in terms of company reputation on perceived quality. H3-1: Brand reputation has a positive effect on perceived quality. H3-2: It is expected that PB and NB would have different influence in terms of brand reputation on perceived quality. H4-1: Product experience has a positive effect on perceived quality. H4-2: It is expected that PB and NB would have different influence in terms of product experience on perceived quality. H5-1: Brand familiarity has a positive effect on perceived quality. H5-2: It is expected that PB and NB would have different influence in terms of brand familiarity on perceived quality. H6: Perceived quality has a positive effect on customer satisfaction. H7: Perceived quality has a positive effect on customer trust. H8: Perceived quality has a positive effect on customer loyalty. H9: Customer satisfaction has a positive effect on customer trust. H10: Customer satisfaction has a positive effect on customer loyalty. H11: Customer trust has a positive effect on customer loyalty. Results from analyzing main effects of research model is shown as

    , and moderating effects is shown as
    . Results This study is designed with 16 research hypotheses, Results from analyzing their main effects show that 9 of 11 hypotheses were supported and other 2 hypotheses were rejected. On the other hand, results from analyzing their moderating effects show that 3 of 5 hypotheses were supported and other 2 hypotheses were rejected. H1-1: (SPC: Standardized Path Coefficient)=-0.04, t-value=-1.04, p>. 05). H1-2: (${\Delta}\chi^2$=1.10, df=1, p> 0.05). H1-1 and H1-2 are rejected, so it is prove that perceived price is not a significant decision variable having influence on perceived quality and there is no significant variable between PB and NB in terms of influence of perceived price on perceived quality. H2-1: (SPC=0.31, t-value=3.74, p<. 001). H2-2: (${\Delta}\chi^2$=3.93, df=1, p< 0.05). H2-1 and H2-2 are supported, so it is proved that company reputation is a significant decision variable having influence on perceived quality and, in terms of influence of company reputation on perceived quality, PB has relatively stronger influence than NB. H3-1: (SPC=0.26, t-value=5.30, p< .001). H3-2: (${\Delta}\chi^2$=16.81, df=1, p< 0.01). H3-1 and H3-2 are supported, so it is proved that brand reputation is a significant decision variable having influence on perceived quality and, in terms of influence of brand reputation on perceived quality, NB has relatively stronger influence than PB. H4-1: (SPC=0.31, t-value=2.65, p< .05). H4-2: (${\Delta}\chi^2$=1.26, df=1, p> 0.05). H4-1 is supported, but H4-2 is rejected, Therefore, it is proved that product experience is a significant decision variable having influence on perceived quality and, on the other hand, there is no significant different between PB and NB in terms of influence of product experience on product quality. H5-1: (SPC=0.24, t-value=3.00, p<. 05). H5-2: (${\Delta}\chi^2$=5.10, df=1, p< 0.05). H5-1 and H5-2 are supported, so it is proved that brand familiarity is a significant decision variable having influence on perceived quality and, in terms of influence of brand familiarity on perceived quality, NB has relatively stronger influence than PB. H6: (SPC=0.91, t-value=19.06, p< .001). H6 is supported, so a fact that customer satisfaction increases as perceived quality increases is proved. H7: (SPC=0.81, t-value=7.44, p<. 001). H7 is supported, so a fact that customer trust increases as perceived quality increases is proved. H8: (SPC=0.57, t-value=7.87, p< .001). H8 is supported, so a fact that customer loyalty increases as perceived quality increases is proved. H9: (SPC=0.08, t-value=0.76, p> .05). H9 is rejected, so it is proved influence of customer satisfaction on customer trust is not significant. H10: (SPC=0.21, t-value=4.34, p< .001). H10 is supported, so a fact that customer loyalty increases as customer satisfaction increases is proved. H11: (SPC=0.40, t-value=5.68, p< .001). H11 is supported, so a fact that customer loyalty increases as customer trust increases is proved. Implications Although most of existing studies have used function, price, brand, design, service, brand name, store name as antecedent variables for perceived quality, this study used different antecedent variables in order to analyze and distinguish purchase group PB and NB through preliminary research. Therefore, this study may be used as preliminary data for a empirical study that is designed to be helpful for practical jobs. Also, this study is made to be easily applied to any practical job because SEM(Structural Equation Modeling), most strongly explaining the relation between observed variable and latent variable, is used for this study. This study suggests a new strategic point that, in order to increase customer loyalty, customer's perceived quality level should satisfied for inducing customer satisfaction, customer trust, and customer loyalty. Therefore, after finding an effective differentiating factors in perceived quality in order to increase customer loyalty through increasing perceived quality, this factor was made to be applied to PB and NB. Because perceived quality factors which is recognized as being important by consumers is different between PB and NB, this study suggests how to efficiently establish marketing strategy by enhancing a factor. Companies have mostly focused on profitability in terms of analyzing customer loyalty, but this study included positive WOM(word of mouth). Hence, this study suggests that it would be helpful for establishing customer loyalty when consumers have cognitive satisfaction and emotional satisfaction together. Limitations This study used variables perceived price, company reputation, brand reputation, product experience, brand familiarity in order to determine whether each constituent factor has different influence on perceived quality between purchase group PB and NB. These characteristic variables are made up on the basis of the preliminary research, but it is expected that more precise research result would be obtained if additional various variables are included in study. This study selected a practical product that is non-durable, low-priced and bestselling product in a discount store through the preliminary research because it can be easily estimated by consumers. Therefore. generalization of study would be more easily obtained if more various product characteristics is included. Regarding a sample used in this study, it was only based on consumers who purchase products in a large-scale discount store located in Seoul and in the capital area. Accordingly, this sample has some geographical limitation, If a study is expanded by including more areas, more representative research results may be produced. Because this study is only designed to analyze consumers who purchase a product in a large-scale discount store, some difference may be found according to characteristics of each business type. In other words, there is certainly some application limitation, so research result from this study may not be applied to other business types. Future research may have fruitful results if it adjusts a variable to each business type.

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  • Nocturnal Arterial Oxygen Saturation Monitoring in Patients with Respiratory Disease (호흡기 질환 환자들에서 야간 동맥혈 산소포화도 감시 성적)

    • Choi, In-Seon;Yang, Jae-Beom;Kim, Young-Chul;Chung, Ik-Joo;Kang, Yu-Ho;Koh, Yeoung-Il;Park, Sang-Seon;Lee, Min-Su;Park, Kyung-Ok
      • Tuberculosis and Respiratory Diseases
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      • v.41 no.2
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      • pp.103-110
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      • 1994
    • To find out the predictors of nocturnal arterial oxygen desaturation in patients with respiratory diseases, transcutaneous oxygen saturation($StcO_2$) monitoring studies using a pulse oximeter were performed during sleep in 20 patients. $StcO_2$ was decreased more than 4% from the baseline value in 18 patients(90%) and more than 10%("Desaturator") in 8(40%). Five of the seven patients(71.4%) with awake $PaO_2$<60mmHg and three of the thirteen patients(23.1%) with awake $PaO_2{\geq}60mmHg$ were "desaturators". The awake $PaO_2/FIO_2$ and $PaO_2/PAO_2$ could distinguish "desaturator" from "nondesaturator", and $PaO_2,\;SaO_2$ or $StcO_2$ could not. These results suggest that the nocturnal oxygen desaturation depends on the severity of the underlying disease rather than the baseline $PaO_2$. Anthropomorphic and lung function factors could not separate between "desaturator" and "non-desaturator", and about a quater of patients with a wake $PaO_2{\geq}60mmHg$ developed significant desaturation. Therefore, it is necessary to monitor the nocturnal arterial oxygen saturation in patients with respiratory diseases regardless of their severity of airflow obstruction or awake $PaO_2$.

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    Changes of Physicochemical Components and Antioxidant Activity of Garlic During its Processing (흑마늘 가공 중 이화학적 성분 및 항산화 활성의 변화)

    • Shin, Jung-Hye;Choi, Duck-Joo;Lee, Soo-Jung;Cha, Ji-Young;Kim, Jeong-Gyun;Sung, Nak-Ju
      • Journal of Life Science
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      • v.18 no.8
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      • pp.1123-1131
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      • 2008
    • This study was performed to confirm of biological function of black garlic, it heated for 11 days at $40{\sim}90^{\circ}C$ (first step: heate for 2 days at $90^{\circ}C$, second step: heated for 4 days at $80^{\circ}C$, third step: heated for 4 days at $60^{\circ}C$ and fourth step: heated for 1 day at $40^{\circ}C$). Samples were analyzed physico-chemical characteristics and antioxidant activity. Hunter L, a and b values were decreased during processing, and then inner part Hunter values were highly decreased at the second step. The moisture contents were decreased to 58.48${\pm}$0.41 g/100 g at fourth step. pH was also acidified to pH 4.22${\pm}$0.02, but O.D. value at 420 nm was increased during processing of black garlic. At fourth step, total phenolics and flavonoids contents were increased about 1.9 and 2.6 folds than first step sample. Also, total pyruvate and thiosulfinate contents were increased about 1.6 and 5.8 folds as change of total phenolic and flavonoid contents, respectively. Fructose contents were the highest level among free sugars and its contents increased to 2,454.45${\pm}$4.20 mg/100 g. Contents of sucrose and maltose were decreased during processing of black garlic. The contents of total minerals were the highest at fourth step (1,009.20${\pm}$6.91 mg/100 g) during its processing. Contents of glutamic acid, proline and aspartic acid were detected higher than other composition amino acids. Taurine and ethanolamine were not detected in the first step sample, but they were detected 0.88${\pm}0.60{\sim}1.06{\pm}$0.04 and 0.28${\pm}0.4{\sim}0.5{\pm}$0.09 mg/100 g in next processing step, respectively. DPPH radical scavenging ability of water and ethanol extracts from black garlic was increased during its processing. Abilities of DPPH radical scavenging were the highest in fourth step sample, its abilities were 67.40${\pm}$0.21% in 1,000 ${\mu}g/ml$ of water extracts. Reducing power was also significantly higher in water extract than ethanol extract on the whole.

    Analysis of Orthotropic Body Under Partial-Uniform Shear Load (부분(部分) 등분포(等分布) 전단하중(剪斷荷重)을 받는 이방성(異方性) 구조체(構造體)의 해석(解析))

    • Chang, Suk Yoon
      • KSCE Journal of Civil and Environmental Engineering Research
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      • v.4 no.1
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      • pp.1-10
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      • 1984
    • This dissertation presents an exact solution for the shearing and normal stresses of an orthotropic plane body loaded by a pairtial-uniform shear load. The solution satisfies the equilibrium and compatibility equations concurrently. An Airy stress function is introduced to solve the problem related to an orthotropic half-infinite plane under a partial-uniform shear load. All the equations for orthotropy must be degenerated into the expressions for isotropy when orthotropic constants are replaced by isotropic ones. The author has evaluated all the equations of orthotropy and succeeded in obtaining exactly identical expressions to the equations of isotropy which were derived independently by means of L'hospital's rule. The analytical results of, isotropy ate compared with the simple results of other investigator. Since a concentrated shear load is a particular case of partial-uniform shear load, all the equations of partial-uniform shear load case are degenerated into the expressions for concentrated load case of isotropy and orthotropy. The formal solution is expressed in terms of closed form. The numerical results for orthotropy are evaluated for two kinds and two different orientations of the grain of wood. The type of wood considered are three-layered plywood and laminated delta wood. The distribution of normal and shearing stresses are shown in figures. It is noted that the distribution of stresses of orthctropic materials dependson the type of materials and orientations of the grain.

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