• Title/Summary/Keyword: modified t-test

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A study on the hull form development of the G/T 340ton class high speed fishery patrol ship (G/T 340톤급 고속 어업지도선의 선형개발에 관한 연구)

  • 이귀주;이광일
    • Journal of Ocean Engineering and Technology
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    • v.11 no.4
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    • pp.221-226
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    • 1997
  • This study was carried out for the hull form development of G/T 340ton class high speed fishery patrol ship by Chosun University at the Circulating Water Channel cooperatively with Korea Maritime Service. Same size of 15knots class fishery patrol ship was selected as a parent form (Model number : CU-015), and modified fore and after body to be suitable for the operation at 20 knots. To minimize the breaking wave in the vicinity of fore body at high speed zone, high bulb nose and slender fore body hull form was chosen as an initial condition. Meanwhile, to ensure the engine room space keeping high resistance-propulsion performance, U-type stern hull form was developed.

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The Effect of Education Program on Primiparas로 Knowledge, Confidence and Accuracy of Behavior in Newborn Care (신생아 돌보기 교육 프로그램이 초산모의 신생아 돌보기 지식, 자신감, 행동 정확도에 미치는 효과)

  • 서영미
    • Journal of Korean Academy of Nursing
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    • v.28 no.4
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    • pp.1060-1074
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    • 1998
  • This study was to find whether the educational program contributed to the increase of knowledge, confidence, and accuracy of behavior in newborn care of the primiparas. The educational program consistes of individual lectures, demostrations, discussion, and practice of newborn care. Also two telephone counseling with the subjects after they are discharged from hospital. This study is a quasi-experimental design using non-equivalent control group pretest-posttest design. Data collection was done from July 21 to Oct 4 in 1997. The subjects were selected from 2 general hospitals and 1 university hosipital in C city, Subjects were 44 primiparas(control group 22, experimental group 22). they were tested on knowledge, confidence, and accuracy of behavior in newborn care. A pretest was done 2-3 days after vaginal delivary(5-6 days after c-sec delivary). A posttest was done 21-28 day(vaginal delivary, c-sec delivary) after delivary. The instruments used for this study were knowledge scale about newbon care developed by the reserarcher, Pharis' confidence scale modified by the researcher and accuracy of behavior scale developed by the reserarcher. Primiparas' knowledge and confidence was tested by questionnaire and Primiparas' accuracy of behavior was tested by structured observational method. Analysis of data was done by using of χ²- test, t -test, paired t -test. The results of this study are summarized as follows : 1) Knowledge of the experimental group was significant higher than the control group(t=-4.94, P=.000). 2) Confidence of the experimental group was significant higher than the control group(t=-.262, P=.012). 3) Accuracy of behavior of the experimental group was significant higher than the control group (t=-.969, P=.000). In conclusion, the newborn care education along with intensive telephon counseling shows a significant promotion of newbon care in primiparas. Thus this program can be recommended as an intervention model for the newborn and primiparas.

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The comparison of the fatigue crack initiation life in a notch (노치부의 피로균열발생 수명 비교)

  • Kim, S.H.;Bae, S.I.;Ham, K.C.;Song, J.I.
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.217-222
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    • 2001
  • For the life evaluating of notched members, it is the best way that performing the real fatigue test of structure containing notch. But this method required generally much times and costs to evaluate fatigue life. So, generally we use the modified S-N curve or several methods to predict fatigue life. In this study, crack initiation life was evaluated by fatigue testing the SAE keyhole specimen and smooth specimen made of Al 7075-T6 alloys using the constant load then obtained S-N curve of smooth specimen and P-N curve of SAE keyhole specimen. And, fatigue lives of keyhole specimen are predicted using some life prediction methods (Nominal range I method, Nominal range II method, FEM analysis) for investigating experimented results, and that were compared with experimental data. Predicted fatigue lives by FEM analysis were corresponded with experimental data between 1/3times and 3times on the whole, and predicted fatigue lives using modified S-N curve (Nominal range I method, Nominal range II method) were nonconservative compared with that of FEM analysis.

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Assessment of shear resistance of corroded beams repaired using SFRC in the tension zone

  • Jongvivatsakul, Pitcha;Laopaitoon, Phattarakan;Nguyen, Yen T.H.;Nguyen, Phuoc T.;Bui, Linh V.H.
    • Computers and Concrete
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    • v.27 no.5
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    • pp.395-406
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    • 2021
  • This study experimentally and analytically investigates the shear behavior of corroded reinforced concrete (RC) beams repaired using steel fiber-reinforced concrete (SFRC) in the flexural zone. The experimental parameters are the corrosion degree (0%, 12%, and 17%) and the steel fiber volume in the SFRC (1.0%, 1.5%, and 2.0%). The test results reveal that corrosion degree significantly affects the shear resistance of the beams. The shear capacity of the beam with the corrosion degree of 17% was higher than that of the uncorroded beam, whereas the shear capacity of the beam with the corrosion degree of 12% was lower than that of the uncorroded beam. The shear efficiency of damaged beams can be recovered by repairing them using SFRC that contains a reasonable amount of steel fibers. In addition, two methods to estimate the shear capacity of the repaired beams are developed using the modified truss analogy and strut-and-tie models. The estimated shear capacity of the beam using the modified truss analogy model agrees well with the experimental data.

Analysis of Thermal Shock in Tool Steels for Hot Forging (열간단조 금형강의 열충격특성연구)

  • Kim, J.W.;Kim, B.J.;Jo, I.S.;Moon, Y.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.14 no.3
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    • pp.155-159
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    • 2001
  • The thermal shock resistance has been investigated and compared in three hot-work tool steels. The resistance to thermal shock is first of all a matter of good toughness and ductility. Therefore, a proper hot-work tool steel should be characterized by high fracture strength and high temperature toughness. In this study, new test method is proposed to measure the thermal shock resistance. New method is basically based on Uddeholm' thermal shock test but some modification has been properly applied. Based on these results, some critical temperature($T_{fractures}$) at which fracture occur can be measured to characterize the thermal resistance of the materials. The specific values of ${\Delta}T$, the temperature difference between holding temperature and $T_{fractures}$, has been successfully used as a measure of the thermal shock resistance in this study, the results showed that the thermal shock method used in this study was properly modified.

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Effect of Porosity on Quality Index of Tensile Property of A356 Casting Alloys (A356합금의 품질지수에 미치는 미소기공율의 영향)

  • Lee, Choong-Do
    • Journal of Korea Foundry Society
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    • v.38 no.5
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    • pp.95-102
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    • 2018
  • The dependence of the tensile properties on variations in the porosity of A356 aluminium alloys was investigated in terms of the quality index of the tensile properties based upon the ultimate tensile strength and elongation as well as the variation of the strength coefficient and strain-hardening exponent with regard to a T6 treatment. The test specimens were prepared by low-pressure die-casting and a subsequent T6 treatment, and the experimental results of a tensile test carried out at room temperature were compared to the theoretical description using a modified constitutive model. The nominal value of the quality index of A356 alloys increases gradually with a lapse of the ageing time upon a T6 treatment, despite the fact that this value is temporarily decreased during the initial stage of ageing from a solutionised condition. Additionally, the quality index depends practically upon the porosity variation with a power law relationship without regard to whether in solutionised or artificial aged conditions. The theoretical description indicates that the strength coefficient directly determines the nominal level of the quality index. Moreover, the overall dependence of the quality index on the porosity variation is remarkably weakened with an increase in the tensile strain, whereas the quality index depends sensitively upon the porosity variation with a low value of the strain-hardening exponent.

The Effects of Hospice Volunteer Education Program on Perceptions about Hospice and the Meaning of Life (호스피스 자원봉사자 교육프로그램 참여군과 비 참여군의 호스피스에 대한 인식과 삶의 의미 비교)

  • Kim, Myung-Sook;Lee, Chung-Sook;Kim, Hyung-Chul
    • Asian Oncology Nursing
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    • v.7 no.2
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    • pp.131-139
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    • 2007
  • Purpose: This study was to compare the perceptions about hospice and the meaning of life between the participants and non-participants of the hospice volunteer education program. Method: Descriptive survey research design was used. Participants were 63, and the data collecting period was from October to December, 2006. Instrument developed by Jung-Hee Kim(1990) and Eun-Ja Lee(1998) was modified to measure the perceptions about hospice. To measure the meaning of life, P.I.L (Purpose In Life) instrument by Crumbaugh and Maholick(1969) was utilized. The data were analyzed using $X^2-test$, t-test and Pearson-Correlation Coefficient. Results: 1. The participants in the hospice volunteer education program demonstrated higher perception scores about hospice than the non-participants (t=5.193, p= .001). 2. The program participants also showed higher scores of the meaning of life than non-participants (t=3.084, p=.005). 3. The perception about hospice and the meaning of life had positive correlation (r= .46, p= .01). Conclusion: Therefore, hospice education program must be established in a continual and systematic way in order to standardize the hospice system in Korea.

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The Effects of Visual Health Promotion Program for Preschool Children (학령전기 아동의 시력건강증진 프로그램 효과)

  • Yoon, Young-Mi
    • The Journal of Korean Academic Society of Nursing Education
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    • v.12 no.2
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    • pp.257-264
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    • 2006
  • Purpose: The purpose of this study is to identify the effects of visual health promotion program for preschool children. Method: The experimental group participating in the visual health promotion program was 32 preschool children and the control group consisted of 34 preschool children by homogeneous age. The visual health promotion program was based on articles related to childern's visual health promotion and previous education program. Data were collected with 3 questionnaires that modified by the investigator. The data was analyzed by the SPSS win 10.0 program using descriptive statistics, $x^2$ test, t-test. Result: The level of knowledge about visual health promotion of preschool children who participated in the visual health promotion program was significantly higher than preschool children who did not participate(t=.02, P<.001). The level of behavior about visual health promotion of preschool children who participated in the visual health promotion program was significantly higher than preschool children who did not participate(t=.31, P<.001). Conclusion: The visual health promotion program developed in this study is an effective strategy for nursing intervention by increasing knowledge and behavior about visual health promotion of preschool children.

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The Mass Production Weapon System Environmental Stress-Screening Test Design Method based on Cost-effective-Optimization (비용 효과도 최적화 기반 양산 무기체계 환경 부하 선별 시험 설계 방법)

  • Kim, Jangeun
    • Journal of Applied Reliability
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    • v.18 no.3
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    • pp.229-239
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    • 2018
  • Purpose: There is a difficulty in Environmental Stress Screening (ESS) test design for weapon system's electrical/electronic components/products in small and medium-sized enterprises. To overcome this difficulty, I propose an easy ESS test design approach algorithm that is optimized with only one environment tolerance design information parameter (${\Delta}T$). Methods: To propose the mass production weapon system ESS test design for cost-effective optimization, I define an optimum cost-effective mathematical model ESS test algorithm model based on modified MIL-HDBK-344, MIL-HDBK-2164 and DTIC Technical Report 2477. Results: I clearly confirmed and obtained the quantitative data of ESS effectiveness and cost optimization along our ESS test design algorithm through the practical case. I will expect that proposed ESS test method is used for ESS process improvement activity and cost cutting of mass production weapon system manufacturing cost in small and medium-sized enterprises. Conclusion: In order to compare the effectiveness of the proposed algorithm, I compared the effectiveness of the existing ESS test and the proposed algorithm ESS test based on the existing weapon system circuit card assembly for signal processing. As a result of the comparison, it was confirmed that the test time was reduced from 573.0 minutes to 517.2minutes (9.74% less than existing test time).

The Effect of Yu-Dong-Kong on Physical Function and Emotional State in Elderly (유동공 체조가 노인의 신체기능과 정서상태에 미치는 효과)

  • Yoo Ji-Soo;Han Shin-Hee
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.6 no.3
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    • pp.507-521
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    • 1999
  • Yu-Dong-Kong exercise is to produce heat from rubbing hands and is composed of 10 different types of exercise using warmed hands. The objective of this research is to evaluate the effect of Yu-Dong-Kong exercise on physical function and emotional state in elderly. The design of research is Nonequivalent Control Group Pretest-Posttest Design. The independent variable is Yu-Dong-Kong exercise, and the dependent variables are physical function and emotional state. Subjects are 18 elderly in the experimental group and 16 elderly in control group. All of them are above 60 year old and live in 1-city, Kyonggi-do. The exercise period was 4 weeks and data were collected from April to August in 1998. The exercise frequency was once a day. The exercise duration was from 10 to 20 minutes. The measurement tools are modified 1) Cornell Medical Index-Health questionnaire and 2) Geriatric Depression Scale. Collected data were analyzed by t-test and paired t-test based on the purposes of research using SPSS-Window package. The results are summarized as follows : 1. There was no difference in pre-exercise physical function between two groups (t=-.95, p=.35). 2. The hypothesis that 'physical function in the experimental group will be improved compared to the control group' was not supported by t-test(t=-.925, p=.362). However. the physical function in the experimental group showed much improvement than that in the control group. 3. The hypothesis that 'emotional state in the experimental group will be improved compared to the control group' was not supported by t-test(t=-1.715, p=.096). However, the emotional state in the experimental group showed much improvement than that in the control group. 4. The hypothesis that 'physical function will be improved in the post-exercise compared to pre-exercise' was not supported by paired t-test(t=.302, p=.766) However, a slight improvement in the physical function was found. For the further study, it is recommended to reevaluate the effect of Yu-Dong-Kong exercise through large number of subjects and long-term study. Also, a separate study with different type of subjects is recommended. In addition, continuation and compliance this strategy for exercise should be developed.

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