• Journal of Forest and Environmental Science
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• 제38권4호
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• pp.239-248
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• 2022

Forestry crane work in a forest harvester or forwarder is regarded as one of most hard work requiring a very high level of operation skill. The operator must handle two or more multi-axes joysticks simultaneously to control the multiple manipulators for maneuvering the crane-tip to its intended location. This study has been carried out to develop a crane-tip controller which can intuitively maneuver the crane-tip, resulting in improving the productivity by decreasing the technical difficulty of control as well as reducing the workload. The crane-tip controller consists of a single 2-axis joystick and a control algorithm run on microcontroller. Lab-scale forestry crane was constructed using electric cylinders. The crane-tip control algorithm has the crane-tip follow the waypoints generated on the given path considering the dead band region using LBO (Lateral Boundary Offset). A speed control gain to change the speed of relevant cylinders relatively is applied as well. By the P (Proportional) control within the control interval of 20 msec, the average error of crane-tip control on the predefined straight path turned out to be 14.5 mm in all directions. When the joystick is used the waypoints are generated in real time by the direction signal from the joystick. In this case, the average error of path control was 12.4 mm for straight up, straight forward and straight down movements successively at a certain constant speed setting. In the slant movement of crane-tip by controlling two axes of joystick simultaneously, the movement of crane-tip was controlled in the average error of 15.9 mm when the crane-tip is moved up and down while moving toward forward direction. It concluded that the crane-tip control was possible using the control algorithm developed in this study.

• Steel and Composite Structures
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• 제45권3호
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• pp.409-423
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• 2022

Nowadays, there is a high demand for great structural implementation and multifunctionality with excellent mechanical properties. The porous structures reinforced by graphene platelets (GPLs) having valuable properties, such as heat resistance, lightweight, and excellent energy absorption, have been considerably used in different engineering implementations. However, stiffness of porous structures reduces significantly, due to the internal cavities, by adding GPLs into porous medium, effective mechanical properties of the porous structure considerably enhance. This paper is relating to vibration analysis of fluidconveying cantilever porous graphene platelet reinforced (GPLR) pipe with fractional viscoelastic model resting on foundations. A dynamical model of cantilever porous GPLR pipes conveying fluid and resting on a foundation is proposed, and the vibration, natural frequencies and primary resonant of such a system are explored. The pipe body is considered to be composed of GPLR viscoelastic polymeric pipe with porosity in which Halpin-Tsai scheme in conjunction with the fractional viscoelastic model is used to govern the construction relation of nanocomposite pipe. Three different porosity distributions through the pipe thickness are introduced. The harmonic concentrated force is also applied to the pipe and the excitation frequency is close to the first natural frequency. The governing equation for transverse motions of the pipe is derived by the Hamilton principle and then discretized by the Galerkin procedure. In order to obtain the frequency-response equation, the differential equation is solved with the assumption of small displacement, damping coefficient, and excitation amplitude by the multiple scale method. A parametric sensitivity analysis is carried out to reveal the influence of different parameters, such as nanocomposite pipe properties, fluid velocity and nonlinear viscoelastic foundation coefficients, on the primary resonance and linear natural frequency. Results indicate that the GPLs weight fraction porosity coefficient, fractional derivative order and the retardation time have substantial influences on the dynamic response of the system.

• 한국지반공학회논문집
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• 제23권1호
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• pp.51-65
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• 2007

본 논문의 목적은 초음파 탐사 방법을 이용하여 지반내의 불연속 물질을 탐측할 수 있는 고해상도의 시스템을 개발하고 실내에서 적용하는 것이다. 초음파 탐측 방법은 불연속면의 경계면에서 반사되어온 반사파를 탐측하고, 이를 배열하여 불연속면의 존재를 찾는 방법이다. 본 논문은 암반내 초음파의 전달 양상, 최적화된 트랜스듀서의 선택, 데이터 획득, 신호처리 방법, 영상화 기법, 그리고 실내 적용실험을 포함하고 있다. 실내실험은 수평이동장치와 회전이동장치를 이용하여 수행된다. 수중에서 수평이동 및 회전실험 결과, 불연속면의 위치와 크기가 정확하게 평가 되었다. 또한 석고시료에서 회전실험결과 석고 내에 존재하는 균열과 공동이 비교적 정확하게 영상화됨을 알 수 있다. 본 논문은 새롭게 제시된 방법이 암반 불연속면 탐측에 매우 경제적이고 효과적인 방법이 될 수 있음을 보여준다.

• 한국간호교육학회지
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• 제30권1호
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• pp.49-60
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• 2024

Purpose: The coronavirus disease 2019 (COVID-19) pandemic has had significant physical and psychological impacts on registered nurses (RNs). This study aimed to identify long COVID symptoms and their associated factors specifically among RNs. Methods: This descriptive correlational study's sample comprised 189 nurses (31.57±5.98 years, 93.7% female) in Korea. Self-reported long COVID symptoms were assessed using the COVID-19 Yorkshire Rehabilitation Scale. Data were collected from December 31, 2022, to January 13, 2023, using the online survey method and were analyzed using independent t-test, Wilcoxon signed-rank test, one-way ANOVA, Pearson's correlation, and a multiple linear regression analysis with the IBM SPSS Statistics 26.0 program. Results: A total of 179 participants (94.7%) experienced one or more long COVID symptoms. The most prevalent symptoms were weakness (77.8%), fatigue (68.3%), breathlessness (67.7%), cough/throat sensitivity/voice change (50.3%), and sleep problems (50.3%). The factors related to long COVID symptoms were marital status, type of institution, working time, acute COVID-19 symptoms, and vaccination status. The quarantine period (β=.26, p<.001) and the nursing workforce after COVID-19 (β=-.17, p=.018) were significantly associated with long COVID symptoms (Adjusted R² =.33). Conclusion: Providing comprehensive recognition is necessary for the understanding of long COVID symptoms and their associated factors among nurses and could promote a long COVID symptom management education program targeted at nurses. Moreover, it could facilitate effective nursing care and education plans for long COVID patients.

• Steel and Composite Structures
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• 제50권2호
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• pp.201-216
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• 2024

This paper is motivated by the lack of studies relating to vibration and nonlinear resonance of fluid-conveying cantilever porous GPLR pipes with fractional viscoelastic model resting on nonlinear foundations. A dynamical model of cantilever porous Graphene Platelet Reinforced (GPLR) pipes conveying fluid and resting on nonlinear foundation is proposed, and the vibration, natural frequencies and primary resonant of such system are explored. The pipe body is considered to be composed of GPLR viscoelastic polymeric pipe with porosity in which Halpin-Tsai scheme in conjunction with fractional viscoelastic model is used to govern the construction relation of the nanocomposite pipe. Three different porosity distributions through the pipe thickness are introduced. The harmonic concentrated force is also applied on pipe and excitation frequency is close to the first natural frequency. The governing equation for transverse motion of the pipe is derived by the Hamilton principle and then discretized by the Galerkin procedure. In order to obtain the frequency-response equation, the differential equation is solved with the assumption of small displacement, damping coefficient, and excitation amplitude by the multiple scale method. A parametric sensitivity analysis is carried out to reveal the influence of different parameters, such as nanocomposite pipe properties, fluid velocity and nonlinear viscoelastic foundation coefficients, on the primary resonance and linear natural frequency. Results indicate that the GPLs weight fraction porosity coefficient, fractional derivative order and the retardation time have substantial influences on the dynamic response of the system.

• Advances in nano research
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• 제16권2호
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• pp.111-125
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• 2024

Recently, a lot of research has been done on the analysis of axial vibrations of homogeneous and FG nanotubes (nanorods) with various aspects of vibrations that have been fully mentioned in history. However, there is a lack of investigation of the dynamic internal resonances of FG nanotubes (nanorods) between them. This is one of the essential or substantial characteristics of nonlinear vibration systems that have many applications in various fields of engineering (making actuators, sensors, etc.) and medicine (improving the course of diseases such as cancers, etc.). For this reason, in this study, for the first time, the dynamic internal resonances of FG nanorods in the simultaneous presence of large-amplitude size dependent behaviour, inertial and shear effects are investigated for general state in detail. Such theoretical patterns permit as to carry out various numerical experiments, which is the key point in the expansion of advanced nano-devices in different sciences. This research presents an AFG novel nano resonator model based on the axial vibration of the elastic nanorod system in terms of derivation from large-amplitude size dependent internal modals interactions. The Hamilton's Principle is applied to achieve the basic equations in movement and boundary conditions, and a harmonic deferential quadrature method, and a multiple scale solution technique are employed to determine a semi-analytical solution. The interest of the current solution is seen in its specific procedure that useful for deriving general relationships of internal resonances of FG nanorods. The numerical results predicted by the presented formulation are compared with results already published in the literature to indicate the precision and efficiency of the used theory and method. The influences of gradient index, aspect ratio of FG nanorod, mode number, nonlinear effects, and nonlocal effects variations on the mechanical behavior of FG nanorods are examined and discussed in detail. Also, the inertial and shear traces on the formations of internal resonances of FG nanorods are studied, simultaneously. The obtained valid results of this research can be useful and practical as input data of experimental works and construction of devices related to axial vibrations of FG nanorods.

• Advances in nano research
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• 제16권3호
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• pp.231-249
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• 2024

When the amplitude of the vibrations is equivalent to that clearance, the vibrations for small amplitudes will really be significantly nonlinear. Nonlinearities will not be significant for amplitudes that are rather modest. Finally, nonlinearities will become crucial once again for big amplitudes. Therefore, the concrete panel system may experience a big amplitude in this work as a result of the high temperature. Based on the 3D modeling of the shell theory, the current work shows the influences of the von Kármán strain-displacement kinematic nonlinearity on the constitutive laws of the structure. The system's governing Equations in the nonlinear form are solved using Kronecker and Hadamard products, the discretization of Equations on the space domain, and Duffing-type Equations. Thermo-elasticity Equations. are used to represent the system's temperature. The harmonic solution technique for the displacement domain and the multiple-scale approach for the time domain are both covered in the section on solution procedures for solving nonlinear Equations. An effective data-driven solution is often utilized to predict how different systems would behave. The number of hidden layers and the learning rate are two hyperparameters for the network that are often chosen manually when required. Additionally, the data-driven method is offered for addressing the nonlinear vibration issue in order to reduce the computing cost of the current study. The conclusions of the present study may be validated by contrasting them with those of data-driven solutions and other published articles. The findings show that certain physical and geometrical characteristics have a significant effect on the existing concrete panel structure's susceptibility to temperature change and GPL weight fraction. For building construction industries, several useful recommendations for improving the thermo-mechanics' behavior of structural concrete panels are presented.

• Journal of Trauma and Injury
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• 제23권2호
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• pp.68-74
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• 2010

Purpose: The purpose of this study is, first, to analyze the risk factors that influence the severity of injury in pediatric multiple trauma patients and, second, to present solutions for the problems related to the treatment of such patients. Our living situations are so complicated that the danger of accidents is truly open to children who are not prepared. We need to draw attention to the increased numbers of various accidents involving children. Methods: We studied patients who visited the Emergency Medical Center at Chosun University Hospital from January 1, 2006, to December 31, 2008. Using medical records, we evaluated the general characteristics: the mechanism of injury, the vital signs, the revised trauma score (RTS), the injury severity score (ISS), and the hemoglibin value, which was checked at the time of visit, and the presence or the absence of emergent on regular surgery. We divided the level of injury as follows: light level (1-8 points), mid level (9-15 points), and serious level (above 16 points). We analyzed the medical data by using SPSS 17.0 for windows. Results: The average age of the patients examined was 8.6 years. The number of 6- to 11-year-old patients was 96, which was the largest, but the degree of injury severity was the highest among infant (0-2 years), according to ISS 7.95(${\pm}6.85$). The frequency of accidents was highest on sunny days, and most accidents occurred from 16:00 to 20:00. The cause of multiple trauma for children was the greatest in the traffic accident, (95 patients, 49.0%). In addition, the trauma caused by traffic accidents showed the highest ISS value ($9.02{\pm}6.42$) and the most serious degree (P=0.004). The ISS level of injury ($8.40{\pm}6.64$) for patients moved from a secondary hospital was higher than that ($6.49{\pm}5.57$) for patients who visited the medical center directly. The severity of injury was highest for patients who used a 119 ambulance ($8.84{\pm}5.80$). According to the injured parts of body, Injuries to the arms and the feet most frequent (79 patients, 40.7%), but the level of injury was the highest for internal organs and chest, $16.42{\pm}8.56$ and $11.23{\pm}6.97$, respectively. Conclusion: We used Abbreviated Injury Scale (AIS) in order to examine the characteristics by injured body part for pediatric multiple trauma patients. Because the degree of injury was the highest for internal organs or the chest, we need to more seriously examine and provide for patients who are suspected of having injuries to the internal organs or the chest. We need to quickly determine the need for surgery in patients with serious injuries to the arms and the feet, which is the greatest in frequency. In particular, we need to consider the surgical care of patients who are not very high in the severity of injury to their brains.

• 대한정형외과 초음파학회지
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• 제5권1호
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• pp.1-8
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• 2012

목적: 견관절의 석회화 건염에서 그 석회화의 크기, 시기나 형태와 관계없이 초음파를 이용한 1회 주사요법(needling)에 의한 석회 침착에 대한 방사선학적 조기 소멸 정도에 대하여 알아보고자 하였다. 대상 및 방법: 2011년 3월부터 9월까지 본원에 내원한 증상이 있는 석회화 건염으로 진단받은 모든 환자에서 1회 초음파 유도하 주사요법을 시행 받은, 총 46명(47 견관절) 을 대상으로 하였다. 주사요법을 시행하기 전 초음파를 이용하여 석회 침착물의 정확한 위치와 형태적 특성을 관찰하였으며 초음파 유도하 주사바늘을 이용하여 침착된 석회에 대하여 가능한 예에서는 흡입을 시도하였고 흡입 실패 시 다발성 천공을 시행하였고 모든 예에서 견봉하-삼각근하 점액낭에 1 ml 리도케인과 1 ml 스테로이드의 혼합액을 주입하여 주었다. 초음파 유도하 주사요법에 의한 침착된 석회의 조기 소멸 정도를 파악하기 위해 주사요법 시행 전과 시술 후 첫 외래 방문시기인 4주째 방사선학적 검사를 시행하여 석회 침착물의 크기, 음영 및 형태의 변화를 비교하였다. 임상적 평가로는 통증과 기능에 대한 Visual Analogue Scale (VAS)와 American Shoulder and Elbow Surgeons (ASES) 점수를 시술 전과 후에 평가하였다. 결과: 남자가 11명, 여자가 35명이었고, 시술 당시 평균 연령은 53.8세(28~71세)이었다. 우측 35예, 좌측 견관절에서 12예로 관찰되었고, 우세 상지측에 발생된 경우는 37예 (78.7%)에서 해당되었다. 주사요법 시행 전 시행한 방사선학적 검사 상 석회 침착의 형태는 31예에서 A형, 16예에서 B형으로 관찰되었고 평균 크기는 $2.9{\pm}6.7$ mm이었다. 초음파 유도하 주사요법 시행 후 4주째 시행한 방사선학적 검사 상 크기나 음영이 변화가 없었던 경우가 10예, 변화를 보였던 경우가 37예에서 관찰되었다. 변화를 보였던 37예 중 크기는 유지되나 음영이 감소되거나 경계가 불분명해진 경우가 14예, 크기가 감소된 경우 13예(50%이상 감소한 경우 4예, 50%미만 감소된 경우 9예), 흔적만 남은 경우 8예, 그리고 완전한 소실을 보인 경우가 2예에서 관찰되었다. 방사선학적 변화를 보였던 군과 보이지 않았던 군의 시술 후 임상적 결과를 비교하여 보았을 때 두 군 간 통계학적 차이는 보이지는 않았으며 시술 전 FAS 분류에 있어 두 군 간 유의한 차이를 보였다(p=0.011). 결론: 견관절의 석회화 건염에서 그 석회화의 크기, 시기나 형태와 관계없이 초음파를 이용한 1회 주사요법(needling) 이후 조기(4주째)에 방사선학적으로 크기나 음영에서 변화를 보이는 예는 79%에서 보였으나 거의 없어지거나 완전한 소멸을 보이는 예는 21%에서만 관찰되었다. 향후 장기적인 추시 관찰을 통하여 석회 침착물의 소멸 여부를 비교해 봄으로써 1회 시술의 결과를 알 수 있을 것으로 사료된다.

• 치위생과학회지
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• 제9권3호
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• pp.327-338
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• 2009

본 연구는 한국의 문화와 실정에 맞는 한국형 스켈링공포에 관한 측정도구를 개발하기 위해 2008년 11월 연구 대상자 720명을 대상으로 개방형 질문을 통해 문항을 수집하였고( 1차 조사), 2008년 12월과 2009년 1월에 스켈링 환자 110명을 대상으로 사전조사를 실시하여 측정도구의 영역설정 및 문항선정을 통해 1차 도구를 개발하였으며 (2차 조사), 2009년 2~3월에 연구대상자 720명에게 설문조사하여 최종적으로 4개 영역과 19개 문항을 결정함으로서 최종적으로 측정도구를 개발하였다. 문항수준 분석결과에서 결측치는 0.003%로 기준의 20%보다 낮아 양호했고, 검사-재검사 신뢰도 검중에서 상관계수가 0.92 이상으로 높았으며, 짝비교 t-검증도 조사 전후 간에 유의한 차이가 없어 신뢰도가 높았다. 문항 내적일치도 역시 전체 영역 내 상관계수 범위가 0.39~0.95로 높았으며, 항목판별타당도는 영역 간 상관계수가 0.56이하로 유의하였다. 영역수준의 분석결과 3개 영역의 평균 범위는 2.06~2.33 이었고 예상치 못한 신체반응의 공포영역은 1.29 이었다. 각 영역의 바닥치와 천장치는 각각 4.3%와 6.8%로 기준의 20% 보다 낮아 적합했고, 요인분석에서 일부 영역의 요인이 단일요인으로 묶이는 것을 제외하연, 각 영역별 문항이 동일 요인으로 묶여졌으며, 확인적 요인분석 결과에서 전반적으로 모형 합치도가 높았다. 스켈링 경험유무별 스켈링공포의 종속변수에 유의하게 영향을 미치는 연수분석에서 스켈링 경험자는 성별과 칫솔방법이 유의성이 있었고, 비 경험자는 성별, 교육수준, 칫솔방법, 그리고 일주 당 운동량 등이 유의했다. 이상으로 본 연구는 스켈링공포에 관한 측정도구를 총 4개 영역 19개 문항을 개발하였다. 향후 개발된 도구는 여러 집단을 대상으로 재평가를 받아 일반화 되어야 할 것이며, 이들 환자들에게 적용함으로서 정기적인 스켈링을 통한 구강보건향상에 기여할 것으로 판단된다.