• 대한치과기공학회지
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• 제11권1호
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• pp.83-88
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• 1989

This investigation was performed to evaluate the effect of four different preteatment techniques on the bond strength of porcelain to non-precious metal alloy. Samples of total of 40 were divided into 4 groups according to the 4 variables which included the 50$\mu$alumina oxide air abrasion, method, the as retention bead method, the L-retention bead method, the Etching method. The completed metal-porcelain samples were compressed in Instron loading machine until gross fracture occured to examine the effect of the complex variables on the bond strength of porcelain to non precious metal alloy. The result obtained were as follows : 1. The difference of bond strength according to four different pretreatment techniques was statistically significant(p<0.01). 2. The difference of bond strength between the ss-retention bead method and the L-retention bead method was not significant statistically(p>0.05) 3. The difference of bond strength between the retention bead method and the etching method was statistically significant(p<0.01). 4. The difference of bond strength between the retention bead method and the 50$\mu$alumina oxide air abrasion method was statistically significant(p<0.01). 5. The difference of bond strength between the etching method and the 50$\mu$alumina oxide air abrasion method was statistically significant(p<0.01).

• 한국과학교육학회지
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• 제19권4호
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• pp.585-594
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• 1999

The purpose of this study is to examine the concept of Greenhouse Effect as understood by middle school high school university students using a closed-form questionnaire. Based on results of the questionnaire which was administered to 619, the extent to which alternative concepts were held was quantified and compared the difference of various group based on grade level. gender, text and major. Also, subjects were divided into two groups, one is middle school students and the other is high school university students and common themes within conceptual framework of each group were identified by factor analysis. The result showed that students confused Greenhouse Effect with ozone layer depletion in stratosphere and linked familiar contamination around everyday life. acid rain. radioactive contamination, nuclear arsenal to Greenhouse Effect. These trends were more appreciable in female than male, biology major than any other major and text did not make any significant difference. In addition, the result of factor analysis showed that two groups linked familiar contamination around everyday life to Greenhouse Effect and high school university students understand the consequences of an increase in the Greenhouse Effect more systematically than middle school student, perceived the relation between the origin of an increase in the Greenhouse Effect and human activity but confused Greenhouse Effect with ozone layer depletion in stratosphere.

• Structural Engineering and Mechanics
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• 제53권2호
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• pp.249-260
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• 2015

Damage detection based on a reference set of measured data usually has the problem of different environmental temperature in the two sets of measurements, and the effect of temperature difference is usually ignored in the subsequent model updating. This paper attempts to identify the structural damage including the temperature difference with artificial measurement noise. Both local damages and the temperature difference are identified in a gradient-based model updating method based on dynamic response sensitivity. The sensitivities of dynamic response with respect to the system parameters and temperature difference are calculated by direct integration method. The measured dynamic responses of the structure from two different states are used directly to identify the structural local damages and the temperature difference. A single degree-of-freedom mass-spring system and a planar truss structure are studied to illustrate the effectiveness of the proposed method.

• Journal of Korea Trade
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• 제24권5호
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• pp.1-17
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• 2020

Purpose - This paper tries to estimate the effects of China's and Japan's free trade agreement (FTA) by panel generalized least squares (GLS). Design/methodology - The GLS model includes the basic gravity theory and Difference in Difference (DD) method to divide FTA conclusion countries and non-FTA conclusion countries with China and Japan. In order to empirically research the difference between Chinese and Japanese FTAs, we use the Difference in Difference in Difference (DDD) method. Findings - This paper finds the distance variable has more influence on Japanese than Chinese trade. The exchange rate indicates that Chinese trade depends on export and Japanese trade has the structure of re-import; shows that the countries that concluded FTAs with China and Japan have more positive trade effects than those that did not; finds the Chinese FTA promotion effects greater than the Japanese FTA because China had pushed ahead with trade policy since joining the WTO in 2001. Originality/value - This study shows that a single country's FTA and trade policies are an important factor concerning not just the promotion of trade but also the issue of trade conflicts.

• 대한한의학방제학회지
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• 제16권1호
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• pp.169-183
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• 2008

In this study, we measured body mass index, visceral fat ratio and 6 parts of body, neck circumference, circumference of upper arm, chest circumference, abdomen circumference, hip circumference, and thigh circumference by bioimpedence analysis system, after taking Gyeongshingangjeehwan16 (GGEx16) in five months except the first period before taking GGEx16 on 49 women who are obesity or high-level obesity. In order to examine the significance test for the effect of obesity improvement of GGEx16, we practices repeated measure ANOVA with values of measurement variables in 6 monthly times. As a result of all measurement variables, there were significant difference (P-value=0.001). Therefore, we can say that GGEx16 is effective about obesity improvement. As it dramatically decreased between second measure period and first measure period for all measure variables, we can see that there were the most effect of GGEx16 in the first time after taking GGEx16. It is known that a important measurement variable to have a effect for obesity improvement about two variable which are body mass index and visceral fat ratio is waist circumference through correlation analysis. The result of whether there are differences to effect of obesity improvement for GGEx16 around the climacteric, there were significant difference for the effect of obesity improvement for GGEx16 around the climacteric about all parts of body (P-value=0.001). There were also powerfully difference in effect of obesity improvement for GGEx16 around the climacteric about all parts of body (P-value=0.001). Especially, the climacteric before is more effective than the climacteric after in the aspect of the effect of GGEx16.

• 한국융합학회논문지
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• 제11권11호
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• pp.155-163
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• 2020

본 연구는 SNS 광고에 있어 SNS 이용동기 및 이용강도에 따라 광고속성 요인들이 광고호감도와 구매의도에 어떠한 영향을 미치고 있는지에 대한 실험연구를 수행하였다. 연구결과, 우선 SNS 이용동기에 따라 차이를 보여 인간관계 관리의 이용동기 이용자에서는 광고내용의 신뢰성이 가장 크게 영향을 미치고 있고 광고의 흥미적 요소인 오락성도 중요 요인으로 영향을 미치고 있다. 관심사 정보공유의 이용동기 이용자에서는 SNS 이용에 대한 광고의 방해성이 가장 크게 부정적인 영향을 미치고 있는 상황에서 광고의 정보제공력을 나타내는 정보성이 긍정적인 중요 요인으로 영향을 미치고 있다. 그리고 이용강도에 따라서도 차이를 보여 높은 이용강도의 이용자에서는 광고내용의 신뢰성과 정보성이 보다 크게 영향을 미치고 있다. 낮은 이용강도의 이용자에서는 광고의 방해성이 가장 크게 부정적인 영향을 미치며 나머지 요인들은 작게 영향을 미치고 있다. 이러한 결과는 SNS의 이용행태 특성에 따른 효과적인 SNS 광고의 중요 요소를 설명할 수 있는 정보를 제공할 수 있다는데 의의가 있다.

• Wind and Structures
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• 제31권4호
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• pp.373-380
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• 2020

For large-scale 5MW offshore wind turbines, the discrete equation of fluid domain and the motion equation of structural domain with geometric nonlinearity were built, the three-dimensional modeling of the blade considering fluid-structure interaction (FSI) was achieved by using Unigraphics (UG) and Geometry modules, and the numerical simulation and the analysis of the vibration characteristics for wind turbine structure under rotating effect were carried out based on ANSYS software. The results indicate that the rotating effect has an apparent effect on displacement and Von Mises stress, and the response and the distribution of displacement and Von Mises stress for the blade in direction of wingspan increase nonlinearly with the equal increase of rotational speeds. Compared with the single blade model, the blade vibration period of the whole machine model is much longer. The structural coupling effect reduces the response peak value of the blade displacement and Von Mises stress, and the increase of rotational speed enhances this coupling effect. The maximum displacement difference between two models decreases first and then increases along wingspan direction, the trend is more visible with the equal increase of rotational speed, and the boundary point with zero displacement difference moves towards the blade root. Furthermore, the Von Mises stress difference increases gradually with the increase of rotational speed and decreases nonlinearly from the blade middle to both sides. The results can provide technical reference for the safe operation and optimal design of offshore wind turbines.

• 대한통합의학회지
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• 제10권3호
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• pp.37-52
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• 2022

Purpose : The purpose of this meta-analysis was to evaluate the effects of electrical stimulation on patients with non-specific low back pain. Methods : Domestic databases were gathered from studies that conducted clinical trials associated with electrical stimulation and its impact on pain of non-specific low back patients. A total of 681 studies were identified, with 12 studies satisfying the inclusion data. The studies consisted of patient, intervention, comparison, outcome, and study design (PICO-SD). The search outcomes were items associated with low back pain. Cochrane risk of bias 2 (RoB 2) was used to evaluate the quality of 12 randomized controlled trials. Effect sizes (Hedges's g) in this study were computed as the corrected standard mean difference (SMD). A random-effect model was used to analyze the effect size because of the high heterogeneity among the studies. Egger's regression and 'trim-and-fill' tests were carried out to analyze the publication bias. Cumulative meta-analysis and sensitivity analysis were conducted to analyze the effect according to the sample size and the consistency of the effect size. Results : The following factors had a large overall effect size (Hedges's g=1.28, 95 % CI=.20~2.36) involving electrical stimulation on non-specific low back pain. The subgroup analysis all showed a statistical difference in the types of study design, electrical stimulation, and assessment tool. No statistically significant difference was found in the meta-regression analysis. Publican bias was found in the data. Conclusion : The findings in this study indicate that electrical stimulation interventions have a positive effect on patients with non-specific low back pain. However, due to the low quality of studies and publication bias, the results of our study should be interpreted cautiously.

• 대한통합의학회지
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• 제11권4호
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• pp.1-15
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• 2023

Purpose : This study investigates the effectiveness of digital therapy for stroke patients in Korea. Methods : A comprehensive database search was performed using KCI, Science on, e-article, RISS, KISS and Korea OpenMed databases for randomized controlled trials (RCTs) that studied the effects of digital therapy on patients who had a stroke. This study includes RCTs published from January 2000 to July 15, 2022, which fulfilled the inclusion and exclusion criteria. A total 697 studies were screened and 30 studies were included in the final analysis. Methodological quality was assessed with the Cochrane's RoB (risk of bias) tool. Meta-analysis was performed using CMA 4.0 software. Results : A total of 56 effect sizes were calculated from the 30 selected studies. As a result of the analysis, the overall effect size of digital therapy was .59 (95 % CI=.43-.74). When classified according to type of intervention, VR (virtual reality) (g=.58, 95 % CI=.40-.75), and CACR (computer assisted cognitive rehabilitation) (g=.62, 95 % CI=.30-.95) were statistically significant. VR showed medium to large effect sizes in cognitive function (g=.78, 95 % CI=.20-1.37), psychosocial function (g=.63, 95 % CI=.20-1.07), and physical function (g=.61, 95 % CI=.38-.83). In the CACR, there was a large effect size in cognitive function (g=.84, 95 % CI=.52-1.15), but there was no significant difference in psychosocial function. Also, there was no significant difference between the two interventions in activities of daily living and no significant difference in the effect size of both interventions according to the intervention session. Furthermore, medium to large effect sizes were found for subacute and chronic stroke patients according to the duration of disease. Conclusion : This study presents evidence that digital therapy has a positive effect on various functions of stroke patients in Korea. The researchers expect to actively accept the new paradigm of digital therapy and continue to apply digital therapy in clinical practice.

• Journal of Radiation Protection and Research
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• 제33권1호
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• pp.21-26
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• 2008

Activity가 20만 dpm인 고상 $^3H$ 표준선원을 사용하여 액체섬광계수기에 대한 교정을 수행할 경우 환경시료와는 Activity 및 Geometry 차이가 존재하고, 계측조건 차이로 인해 많은 불확실성이 존재할 수 있지만 이에 대한 연구결과가 없는 실정이다. 따라서 본 연구에서는 민감도분석을 통해 최적의 계측조건을 도출한 후 그 결과에 근거하여 Geometry 및 Activity 차이에 의한 영향을 정량적으로 평가하였고, 각 항목에 의한 영향이 나타날 경우 추가실험을 통해 원인을 규명하였다. 계측 결과에 대한 검증을 수행하기 위해 Chi-square test와 방사능오차분석을 수행하였고, 민감도분석 결과 본 연구에서 제안한 방법이 기존 방법에 비해 $1{\sim}3%$정도 오차가 감소하였다. 방사능오차분석 결과 Activity 차이에 의한 영향은 무시할 수 있었지만 Geometry 차이에 의한 영향이 크게 나타났고, 이에 대한 원인을 규명한 결과 비수용성인 플라스틱용기는 반사체 역할을 하였고, Activity가 높을수록 플라스틱에 의한 영향은 무시할 수 있었으며, 선원형태 차이에 의한 영향이 지배적인 것으로 나타났다.