• Title/Summary/Keyword: Difference-in-Differences model

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A Comparison of the Atmospheric CO2 Concentrations Obtained by an Inverse Modeling System and Passenger Aircraft Based Measurement (인버스 모델링 방법을 통해 추정된 대기 중 이산화탄소 농도와 항공 관측 자료 비교)

  • Kim, Hyunjung;Kim, Hyun Mee;Kim, Jinwoong;Cho, Chun-Ho
    • Atmosphere
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    • v.26 no.3
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    • pp.387-400
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    • 2016
  • In this study, the atmospheric $CO_2$ concentrations estimated by CT2013B, a recent version of CarbonTracker, are compared with $CO_2$ measurements from the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project during 2010-2011. CarbonTracker is an inversion system that estimates surface $CO_2$ fluxes using atmospheric $CO_2$ concentrations. Overall, the model results represented the atmospheric $CO_2$ concentrations well with a slight overestimation compared to observations. In the case of horizontal distribution, variations in the model and observation difference were large in northern Eurasia because most of the model and data mismatch were located in the stratosphere where the model could not represent $CO_2$ variations well enough due to low model resolution at high altitude and existing phase shift from the troposphere. In addition, the model and observation difference became larger in boreal summer. Despite relatively large differences at high latitudes and in boreal summer, overall, the modeled $CO_2$ concentrations fitted well to observations. Vertical profiles of modeled and observed $CO_2$ concentrations showed that the model overestimates the observations at all altitudes, showing nearly constant differences, which implies that the surface $CO_2$ concentration is transported well vertically in the transport model. At Narita, overall differences were small, although the correlation between modeled and observed $CO_2$ concentrations decreased at higher altitude, showing relatively large differences above 225 hPa. The vertical profiles at Moscow and Delhi located on land and at Hawaii on the ocean showed that the model is less accurate on land than on the ocean due to various effects (e.g., biospheric effect) on land compared to the homogeneous ocean surface.

A Study of the Relationship between 3D Model and 3D Garment Simulation

  • Kim, Yeo-Sook;Park, Hye-Won
    • Journal of the Korean Society of Clothing and Textiles
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    • v.36 no.6
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    • pp.631-640
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    • 2012
  • This research project investigates the differences of various body locations (between 3D body models) and drapes garments digitally onto 3D body models. Three different subject models will be given explication. It consisted of (1) data collection of three-dimensional scans (2) creation of 3D body representations (3) comparison of avatar shapes and measurements (4) visualization and assessment of 3D body models and their 3D virtual garments. The study tests a theory of impact by differences in avatars by pattern design. A visual inspection of avatars showed clear differences between the six avatar types (in the generating process); however, there was notably less difference between 3D garment simulations based upon the six avatars produced. This demonstrated that there was less influence on the 3D garments than was predicted after a visual inspection of the avatars.

Comparative study of accuracy of digitized model fabricated by difference optical source of non-contact 3D dental scanner (치과용 스캐너의 광원에 따른 디지털 모형의 정확도 비교연구)

  • Kim, Jae-Hong;Lee, Jung-Soo;Shim, Jeong-Seok
    • Journal of Technologic Dentistry
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    • v.39 no.4
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    • pp.227-233
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    • 2017
  • Purpose: The purpose of this study was to evaluate the validity of digital models fabricated by difference optical source of non-contact 3D dental scanner. Methods: A master model with the prepared upper full arch tooth was used. Stone model(N=10) were produced from master model, and on the other hands, digital models were made with the 3D dental scanner(Blue, white, red optical source). The linear distance between the reference points were measured and analyzed on the Delcam $Copycad^{(R)}$ graphic software. The results were statistically analyzed using the one-way ANOVA and Tukey's HSD test(${\alpha}=0.05$). Results: There were considerable differences in mean values between optical source within each color(blue, white, red), and this difference was not statistically significant(p>0.05). Conclusion : Three different color of dental scanner optical source showed clinically acceptable accuracies of full arch digital model produced by them. Besides, these results will have to be confirmed in further clinical studies.

Preliminary Study on the Influence of Culture Differences between the Europe and Korea on the Negotiation Outcomes (유럽과 한국의 문화 차이가 협상성과에 미치는 영향에 관한 서설적 연구)

  • Hyun-Hyeok Park;Myong-Sop Pak
    • Korea Trade Review
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    • v.46 no.2
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    • pp.229-243
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    • 2021
  • This study aims to establish a research model to see how cultural differences affect negotiation outcomes. People from different countries tend to communicate in slightly different ways. So Recognizing the cultural differences in global businesses is an important preparation process and strategy. If such preparations are not made before doing business with companies in other cultures, many conflicts could arise in the negotiation process and even the negotiations could break down. Therefore, it is important to recognize cultural differences and establish appropriate strategies in international negotiations, and it is necessary to take a look at the factors that affect them one by one. For the purpose of this study, Cultural differences based on Edward Hall's context theory and Personal characteristics were set as moderator variables. and The EU countries(low context cultures) and the Korea(high context cultures) were sampled to study the effects of Negotiation strategy(Problem-Solving Approach).

실험동물 마우스의 혈액세포 분포에 관한 연구

  • Ian C. Guest
    • Toxicological Research
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    • v.7 no.1
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    • pp.47-50
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    • 1991
  • Hematological studies in two strains of normal laboratory mice, namely ICR and ddY which were produced in Koren were carried out. Blood analysis was performed by using different methods, a fully automated analyzer (ELT 1, 500), Coulter counter (model S plus IV) and manual technique to examine possible differences resulting from methodolgies'slight differences among the values of blood parameters were obtained. There was a slight difference noted between sexes, however, similar values were obtained from both strains.

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Breast Cancer Frequency and Exposure to Cadmium: A Meta-Analysis and Systematic Review

  • Rahim, Fakher;Jalali, Amir;Tangestani, Raheleh
    • Asian Pacific Journal of Cancer Prevention
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    • v.14 no.7
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    • pp.4283-4287
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    • 2013
  • Background: In this meta-analysis we review evidence suggesting that exposure to cadmium is a cause of breast cancer. Materials and Methods: We conducted Medline/PubMed and Scopus searches using selected MeSH keywords to identify papers published from January 1, 1980 through January 1, 2013. Data were merged and summary mean differences were estimated using either a random-effects model or a fixed-effects model. Results: There were 13 studies including 978 exposed cases and 1,279 controls. There was no statistically significant difference in the frequencies of breast cancer between cadmium-exposed and control groups, and the summary estimate of mean difference was 0.71 (95%CI: 0.33-1.08). However, stratification showed that there were statistically significant differences in the frequencies of breast cancer between cadmium-exposed and control groups among Asian compared with Caucasian population, and the summary estimates of mean difference were 1.45 (95%CI: 0.62-2.28) vs. 0.25 (95%CI: -0.09-0.6), respectively. There was a difference in the frequencies of breast cancer between cadmium-exposed and control groups in peripheral venous blood sampling methods, and the summary estimate of mean difference was 1.41 (95%CI: 0.46-2.37). Conclusions: Data indicate that the frequencies of breast cancer might be an indicator of early genetic effects for cadmium-exposed populations. However, our meta-analysis was performed on population-based studies; meta-analysis based on individual data might provide more precise and reliable results. Therefore, it is necessary to construct an international database on genetic damage among populations exposed to cadmium that may contain all raw data of studies examining genetic toxicity.

Relationship among FDI, Economic Growth, and Employment (외국인직접투자와 경제성장 및 고용간 관계)

  • Kang, Gi-Choon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.12
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    • pp.574-580
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    • 2019
  • In this paper, the economic performance of the Jeju Free International City and the Free Economic Zone is investigated using statistical testing and the difference in differences (DID) model with data on foreign direct investment (FDI), gross regional domestic product (GRDP), and employment-to-population ratio (EPR). The relationships among FDI, GRDP, and EPR are also investigated using the panel vector error-correction model on the regional data. The compound average growth rate of actual investment, and the ratio of FDI received to FDI declared in the capital region were higher than in the non-capital region. For the growth and relative volume of FDI received, seven regions out of 16 were found to be low in growth and small in relative volume. The results of statistical testing showed statistically significant differences in some variables, except for two regions, but DID estimates that determine the pure policy effect of zone designation showed statistical insignificance. On the other hand, the explanatory power among the three variables was found to be quite limited, but it was greater in the cities, provinces, and non-capital region. In summary, it is necessary to establish the FDI inducement mechanism so the inflow of FDI can increase GRDP and EPR.

Calculations of Pressure Difference in Orifice Flowmeter using CFD (CFD를 이용한 오리피스 유량계의 차압계산)

  • Kim, Hong-Min;Kim, Kwang-Yong;Her, Jae-Young;Ha, Young-Chul
    • 유체기계공업학회:학술대회논문집
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    • 2001.11a
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    • pp.400-403
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    • 2001
  • In this study, commercial CFD code, i.e, CFX-4.3 is used to analyze the flow field and to calculate pressure differences in an orifice flowmeter. Four numerical schemes and five turbulence models are tested. Hybrid scheme and Reynolds stress model show the best performance. Chosen scheme and turbulence model are applied to predict pressure differences through the orifice for the diameter ratios, 0.3, 0.5, and 0.7. And, the results are compared with the experimental data. The results show that the calculation error is inversely proportional to the diameter ratio, and is proportional to the mass flow rate.

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Analysis of Door Height Difference and Door Flatness Difference of Built-in Side-by-Side Refrigerator Using Cabinet-Door Integrated Model (캐비닛-도어 통합모델을 이용한 빌트인 양문형 냉장고의 도어 상하단차와 앞뒤단차 해석)

  • Lee, Boo-Youn
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.5
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    • pp.76-83
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    • 2018
  • A cabinet-door integrated finite element model was constructed for a built-in side-by-side refrigerator with an ice dispenser, and its deformation was analyzed using the ANSYS finite element software. As loads, the food load needed to fill in the cabinet and doors and the thermal load occurring during normal operation conditions were taken into consideration. The door height difference (DHD) and door flatness difference (DFD) between the two doors of the freezing and refrigerating compartments were derived. The DHD and DFD under the assembled condition without applied loads satisfied the acceptance criteria specified by the refrigerator manufacturer. It appeared that the food load increases the DFD slightly. The thermal load tends to increase the differences because of the thermal deformation, especially the DFD, of the cabinet and doors.

Differences of Gender Perception in Adopting Cashless Transaction Using Technology Acceptance Model

  • SUBAWA, Nyoman Sri;DEWI, Ni Komang Arista;GAMA, Adie Wahyudi Oktavia
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.2
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    • pp.617-624
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    • 2021
  • The purpose of this study is to develop a Technology Acceptance Model (TAM), to determine differences in gender perceptions in adopting non-cash transactions. In this study, the authors provide a measurement of differences in gender perceptions in adopting cashless, which refers to perceived usefulness, perceived ease-of-use, and perceived security. Respondents in this study were students from the millennial generation who are very familiar with the use of technology, especially non-cash transactions. The data collection technique used in this study was a survey, by distributing questionnaires to 260 respondents. The data were processed statistically through Structural Equation Modeling (SEM). The results of this study indicate that for men, ease-of-use of transactions does not increase the use of non-cash transactions. Meanwhile, for women, perceived ease-of-use has a significant and positive effect on the use of non-cash transactions. Furthermore, perceptions of usability and security have a positive and significant impact on using non-cash transactions. It was also found that female students had a positive, but not significant, effect on the use of non-cash transactions. This means that there has been a difference in the perception of gender, between men and women, in responding to the use of non-cash transactions.