• Title/Summary/Keyword: force-control

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Numerical Analysis of EPB TBM Driving using Coupled DEM-FDM Part I : Modeling (개별요소법과 유한차분법 연계 해석을 이용한 EPB TBM 굴진해석 Part I : 모델링)

  • Choi, Soon-wook;Lee, Hyobum;Choi, Hangseok;Chang, Soo-Ho;Kang, Tae-Ho;Lee, Chulho
    • Tunnel and Underground Space
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    • v.30 no.5
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    • pp.484-495
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    • 2020
  • To numerically simulate the advance of EPB TBM, various type of numerical analysis methods have been adopted including discrete element method (DEM), finite element method (FEM), and finite difference method (FDM). In this paper, an EPB TBM driving model was proposed by using coupled DEM-FDM. In the numerical model, DEM was applied in the TBM excavation area, and contact properties of particles were calibrated by a series of triaxial tests. Since the ground around the excavation area was coupled with FDM, the horizontal stress considering the coefficient of earth pressure at rest could be applied. Also, the number of required particles was reduced and the efficiency of the analysis was increased. The proposed model can control the advance rate and rotational speed of the cutter head and screw conveyor, and derive the torque, thrust force, chamber pressure, and discharging during TBM tunnelling.

Quality Characteristics of Low-Fat Sausage Containing Curcumin Extract during Cold Storage (울금 추출물 함유 저지방 소시지의 냉장저장 중 품질 특성)

  • Kim, Il-Suk;Jin, Sang-Keun;Park, Ki-Hoon;Jeong, Ki-Jong;Kim, Dong-Hoon;Yang, Mi-Ra;Chung, Young-Sin
    • Food Science of Animal Resources
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    • v.27 no.3
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    • pp.255-261
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    • 2007
  • The effects of curcumin extract on the physicochemical, microbial and sensory properties of low-fat sausages during refrigerated storage were studied. Sausage products were produced with three different formulations including 0%, 2.5%, and 5.0% curcumin extract. Low-fat sausages made with the addition of curcumin extract had lower (p<0.05) crude fat content, pH and TBARS values than the control sample. The addition of curcumin extract did not affect the water holding capacity, cooking loss, shear force, meat color, texture profile, and total bacterial count in low-fat sausages duringstorage (p>0.05). With regard to sensory evaluation, 2.5% curcumin extract added to low-fat sausages resulted in a high overall acceptability (p<0.05). In conclusion, low-fat sausages with added 2.5% curcumin extract had a higher acceptability and lipid oxidative stability during storage than products without curcumin extract.

The Study on the Process of Juvenile Delinquency and It's Prevention Program (청소년 비행화 과정 개입 프로그램 개발에 관한 연구 -비행화 예방 집단활동 프로그램의 효과성 분석 -)

  • Lee, Ik-Seop;Kim, Geun-Sik
    • Korean Journal of Social Welfare
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    • v.37
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    • pp.381-405
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    • 1999
  • The primary purpose of this study is to design and perform juvenile group program and. to evaluate the effectiveness of that program The group was consisted of 10 fourth-grade elementary school boys who have had such factors that might force themselves to be delinquent, for example, broken family, having delinquent siblings or friends, family violence, and etc. The group had been held once a week and continued for 5 months. The effectiveness of that program is evaluated quantitatively and qualitatively through goal-attainment model. The ultimate goal of this program is reduction of delinquency stimulating factors which are operationalized with overall self-esteem - family related self-esteem, friend related self-esteem, and school related self-esteem. Quantitative evaluation is performed by pre- and post-test with Hare Self-Esteem Scale. Case records, family records, group activities records, and reports from schools are analyzed for the qualitative evaluation. According to paired samples t-test scores, average overall self-esteem scores of experimental group members were escalated from 67.57 to 74.86, and this difference between pre-test and post-test was statistically significant. Difference of experimental group was bigger and more striking than that of control group. These results suggest that designed and performed group program in this study would be effective in preventing juvenile from being delinquent.

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ORTHODONTIC TREATMENT WITH MINISCREWS IN MIXED DENTITION (혼합치열기의 miniscrew를 이용한 교정치료)

  • Lim, Su-Min;Yang, Yeon-Mi;Kim, Jae-Gon;Baik, Byeong-Ju;Lee, Yong-Hun;Shin, Jeong-Geun
    • Journal of the korean academy of Pediatric Dentistry
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    • v.35 no.2
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    • pp.367-375
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    • 2008
  • Anchorage plays an important role in orthodontic treatment. Skeletal anchorage like the miniscrew is considered a more effective method in anchorage control than conventional anchorage which needs much patient's cooperation. The miniscrew offers many advantages. 1) It is easy to insert and to remove. 2) It can endure the force needed for moving teeth. 3) It can be immediately loaded and 4) Patient cooperation is not needed. 5) It is economic compared to other skeletal anchorage systems. In comparison to adult's bones, children's bones have comparatively poor bone quality and quantity. Therefore, it is hard to obtain primary stability in younger patients. However, if the miniscrew can be retained successfully, it will be effective in many orthodontic treatments. In these cases, we used the miniscrew in correcting of diastema, in aligning dental midline, and in rendering a forced eruption of impacted tooth in mixed dentition patient. We obtained satisfactory results.

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Predictors of Knowledge Level and Awareness towards Breast Cancer among Turkish Females

  • Aydogan, Umit;Doganer, Yusuf C.;Kilbas, Zafer;Rohrer, James E.;Sari, Oktay;Usterme, Necibe;Yuksel, Servet;Akbulut, Halil;Balkan, Salih M.;Saglam, Kenan;Tufan, Turgut
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.1
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    • pp.275-282
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    • 2015
  • Background: Breast cancer (BC) is the most-common malignancy of women worldwide. Though there are differences among developed and developing countries, BC remains the most common cancer type of women in Turkey. Objective: This study aimed to identify the level of knowledge, awareness, and their potential predictors towards BC in Ankara, Turkey. Materials and Methods: The present descriptive study was conducted on 376 females attending a breast health outpatient clinic. A self-administered questionnaire was designed to evaluate knowledge level about BC and predictors effecting its level. Data analysis was performed using the chi-square test. A value of p<0.05 was considered statistically significant. Results: Mean age of the participants was $46.2{\pm}9.93$ (22-75). The majority (92.6 %) were married; 41.5% were educated less than nine years. Most of the women were housewives (82.7%) and, were living in an urban region (86.4%). Predictors of effecting responses to seven knowledge and awareness questions about BC varied from demographic features including older age groups, higher educational levels, being married, living in an urban area, being employee, smoking, having greater BMI to additional attributes associated breast health such as the increased number of births, applying for the purpose of control, positive family history of breast diseases, any diagnoses of breast diseases and performing BSE practice. Conclusions: It was determined that females in Turkey have better knowledge of BC than other developing countries even though it is not at the desired level. These findings revealed that females should be more informed about BC risk factors, prognosis and treatments by primary health-care providers to counteract the ascending burden of this disease.

Study for Characteristic of Frictional Heat Transfer in Rotating Brake System (회전을 고려한 브레이크 디스크의 마찰열전달 연구)

  • Nam, Jiwoo;Ryou, Hong Sun;Cho, Seong Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.817-822
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    • 2017
  • The braking system is one of the most important components in vehicles and machines. It must exert a reliable braking force when they are brought to a halt. Generally, frictional heat is generated by converting kinetic energy into heat energy through friction. As the kinetic energy is converted into heat energy, high temperature heat is generated which affects the mechanical behavior of the braking system. Frictional heat affects the thermal expansion and friction coefficient of the brake system. If the temperature is not controlled, the brake performance will be decreased. Therefore, it is important to predict and control the heat generation of the brake. Various numerical analysis studies have been carried out to predict the frictional heat, but they assumed the existence of boundary conditions in the numerical analysis to simulate the frictional heat, because the simulation of frictional heat is difficult and time consuming. The results were based on the assumption that the frictional heat is different from the actual temperature distribution in a rotating brake system. Therefore, the reliability of the cooling effect or thermal stress using the results of these studies is insufficient. In order to overcome these limitations and establish a simulation procedure to predict the frictional heat, this study directly simulates the frictional heat generation by using a thermal-structure coupling element. In this study, we analyzed the thermo-mechanical behavior of a brake model, in order to investigate the thermal characteristics of brake systems by using the Finite Element method (FEM). This study suggests the necessity to directly simulate the frictional heating and it is hoped that it can provide the necessary information for simulations.

Effects of supplemented culture media from solid-state fermented Isaria cicadae on performance, serum biochemical parameters, serum immune indexes, antioxidant capacity and meat quality of broiler chickens

  • Liu, Shaoshuai;Yan, Wenjuan;Ma, Chang;Liu, Yajing;Gong, Limin;Levesque, Crystal;Dong, Bing
    • Asian-Australasian Journal of Animal Sciences
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    • v.33 no.4
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    • pp.568-578
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    • 2020
  • Objective: The objective of this study was to investigate effects of supplementation of culture media from solid-state fermented Isaria cicadae (I. cicadae) on performance, serum biochemical parameters, serum immune indexes, antioxidant capacity and meat quality of broiler chickens. Methods: A total of 648 Arbor Acres male broiler chickens(1 d; average body weight, 42.93±0.47 g) were randomly assigned to 6 treatments, each with six replicates and 18 broiler chickens per replicate. Broiler chickens were fed phase I (d 1 to 21) and phase II (d 22 to 42) diets. The phase I diets were corn and soybean-meal based diets supplemented with 0%, 2%, 4%, 6%, 8%, or 10% culture media from solid-state fermented I. cicadae respectively. The phase II diets were corn and soybean-meal based diets supplemented with 0%, 1.33%, 2.67%, 4.00%, 5.32%, or 6.67% culture media from solid-state fermented I. cicadae respectively. Results: In phase I, the broiler chickens with the supplementation of culture media had increased body weight gain and feed intake (linear and quadratic, p<0.05) with increasing inclusion of culture media. The levels of serum total antioxidant capacity (T-AOC), glutathione (GSH) and superoxide dismutase (SOD) increased linearly (p<0.05). In phase II, levels of serum T-AOC and interleukin-1β increased linearly (p<0.05), and GSH increased (p<0.05). In the kidney, GSH and glutathione peroxidase (GSH-Px) concentrations increased (linear and quadratic, p<0.05) and SOD concentration increased linearly (p<0.05). Compared to the control, shear force and drip loss of breast muscle decreased (linear and quadratic, p<0.05). Drip loss of leg muscle decreased linearly and quadratically (p<0.05). Conclusion: Dietary supplementation of culture media from solid-state fermented I.cicadae which was enriched in both wheat and residual bioactive components of I. cicadae enhanced the growth performance of broiler chickens. It also improved body anti-oxidative status and contributed to improve broiler meat quality.

Development and Application of Evaluation Technique for Revetment for Nature-Friendly River Improvement (자연 친화적 하천정비를 위한 호안평가기법의 개발 및 적용)

  • Kim, Yun-Hwan;Park, Nam-Hee;Jin, Young-Hoon;Kim, Chul
    • Journal of Korea Water Resources Association
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    • v.40 no.12
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    • pp.1007-1014
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    • 2007
  • Recently, existing river improvement methods for flood control purpose have changed into nature friendly river improvement methods and the efforts to improve the river environment including river restoration have been made, and close-to-nature river improvement and nature friendly river restoration are actively conducted all over the country. In the present situation where various revetment methods are used after the introduction of the concept of close-to-nature river improvement, the environmental characteristics of rivers need to be considered to apply more suitable revetment methods. Therefore, as a precedent study for the development of revetment evaluation techniques and methods for close-to-nature river improvement, the present study suggested evaluation techniques using detailed survey items through field survey. Evaluation items of hydraulic stability consist of mode of streamline, stream bed gradient, flow velocity and tractive force ratio and those of environmental efficiency consist of revetment of vegetation, state of river water, land use of the terrace land on the river, vegetation and materials of the terrace land on the river. Each item was graded with the point 1 through 5. Hydraulic stability and environmental efficiency was evaluated by the points which were averaged in each items. As the result of the application of the proposed evaluation technique, it was found that a number of existing revetments excessively focus on hydraulic stability with little consideration about environmental term. It is expected that the proposed technique in the present study can be used as a base for providing guidelines to construct the design and construction of revetments in the future.

Development Of EPC Project Management Procedure Manual System For Plant Project Management (플랜트 프로젝트관리를 위한 EPC전자업무절차시스템 개발)

  • Park, Bum-Jin;Lee, Min-Jae
    • Proceedings of the Korean Institute Of Construction Engineering and Management
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    • 2006.11a
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    • pp.487-491
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    • 2006
  • As Korea has been industrialized high recently, the constructional plant part which is the major driving force to Korean economic growth is being developed. In spite of the great importance, there are many ill-prepared parts in EPC project management procedure, and working in practice of EPC project management procedure manual is not systematic. That is why the governmental progressive policy on the relevant technology and the establishment of EPC project management procedure are needed. This study was aimed to derive reform measures by analyzing problems of EPC project management procedure manuals which are in use at 13 large-sized construction companies currently. The reform measures which are based on the theory of PMI(Project Management Institute)'s PMBOK(Porjcet Management Body Of Knowledge) are about deriving administration factors to control the project, and EPC project administration factors are derived from the definition of CMAA(Construction Mangement Association of America). The reformed electronic EPC project management procedure manual system is set up by standardizing derived administration factors.

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Process Optimization for Reduction of Waste Acids of Electropolishing Solution using Round Bus Bar (구형 부스바를 이용한 전해연마액의 폐산 폐기물 감소를 위한 공정 최적화)

  • Kim, Soo Han;Cho, Jaehoon;Park, Chulhwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.722-727
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    • 2016
  • In this study, we attempted to reduce the generation of waste acids in the electropolishing process by improving the current efficiency. The optimum conditions of the electropolishing process when using the round bus bar were determined by the Taguchi method. The current density, polishing time, electrolyte temperature and flow rate were selected as the control factors for the current efficiency in the electropolishing process. An orthogonal array was created by considering three levels for each factor and experiments were carried out. The larger-the-better SN ratios were calculated by the Taguchi method. The current density was the most important factor affecting the current efficiency and the polishing time was the least important one. The optimum conditions to minimize the generation of waste acids were a current density of $45A/dm^2$, polishing time of 4 min, electrolyte temperature of $65^{\circ}C$ and flow rate of 7 L/min. The results of the ANOVA confirmed that the effects of the current density, electrolyte temperature and flow rate are significant at the 95% confidence level. The increase in the contact area and contact force afforded by using the round bus bar improved the current efficiency which, in turn, reduced the amount of waste acids generated. Further research is planned to investigate the effect of the type of bus bar on the current efficiency.