• Geomechanics and Engineering
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• 제33권2호
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• pp.133-140
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• 2023

Soil erosion can cause scouring and failures of underwater structures, therefore, various soil improvement techniques are used to increase the soil erosion resistance. The microbially induced calcium carbonate precipitation (MICP) method is proposed to increase the erosion resistance, however, there are only limited experimental and numerical studies on the use of MICP treatment for improvement of surface erosion resistance. Therefore, this study investigates the improvement in surface erosion resistance of sands by MICP through laboratory experiments and numerical modeling. The surface erosion behaviors of coarse sands with various calcium carbonate contents were first investigated via the erosion function apparatus (EFA). The test results showed that MICP treatment increased the overall erosion resistance, and the contribution of the precipitated calcium carbonate to the erosion resistance and critical shear stress was quantified in relation to the calcium carbonate contents. Further, these surface erosion processes occurring in the EFA test were simulated through the coupled computational fluid dynamics (CFD) and discrete element method (DEM) with the cohesion bonding model to reflect the mineral precipitation effect. The simulation results were compared with the experimental results, and the developed CFD-DEM model with the cohesion bonding model well predicted the critical shear stress of MICP-treated sand. This work demonstrates that the MICP treatment is effective in improving soil erosion resistance, and the coupled CFD-DEM with a bonding model is a useful and promising tool to analyze the soil erosion behavior for MICP-treated sand at a particle scale.

• 동서간호학연구지
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• 제11권2호
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• pp.137-145
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• 2005

Purpose: This study has been attempted as one of the Quality Improvement activities in order to provide with intravenous injection control and to confirm the evaluation from the patients and their guardians, and also from nurses themselves. Method: The subject of this intravenous injection control was a control group of 239 patients and 176 nurses, a comparison group of 128 patients and 146 nurses. The tool consisted of hospitality (towards patients), explanation, and infection prevention activities. The collected data were analysed using SPSS Windows 11.0 program for percentage, $X^2$-test and t-test. Result: 1) The nurses who were instructed in standardised intravenous injection control received more satisfactory evaluation from the patients(t=-2.89, p=.004) than the nurses who were not. However, in the subdivisions, the explanation field was the only one to receive a more satisfactory evaluation(t=-1.14, p=.255). 2) The nurses who were instructed in standardised intravenous injection control showed higher performances in intravenous injection control (t=-4.21, p=.000) than the nurses who were not. In the subdivisions, hospitality, explanation, and infection prevention activities all showed effectiveness ($t=-2.35{\sim}3.90$, $p=.020{\sim}.000$). Conclusion: From the results stated above, it can be concluded that standardised intravenous injection control instruction for nurses brought out better evaluation, i.e. satisfaction, from the patients and their guardians, and the nurses who received the instruction showed better performances in intravenous injection control.

• 한국정밀공학회지
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• 제3권2호
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• pp.62-75
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• 1986

An experimental investigation of the machining characteristics such as cutt- ing resistance, surface roughness and tool wear in turning the test pieces of SM45C steel with both coated and uncoated carbide tool tips under various cutting conditions was conducted. Also a specially designed simple vibration damping device was experimentally evaluated for its effectiveness on machined surface roughness and a vibration test was conducted to confirm its ability to reduce the amplitude. Based on these tests finding, the following conclusions are made; 1. The cutting resistance($\textrm{p}_{1}$) increases as the depth of cut(d) increases at fixed feed rate(f) over the cutting speed(v) range of 43-226 m/min and p decreses about 18% average when V is increased for fixed d and f. At V= 226m/min, $\textrm{p}_{1}$/for A, C tips are about the same level but $\textrm{p}_{1}$ for B tip is 15% less than A, C tips. 2. The specific cutting resistance(Ks) at V=226 m/min was derived for A, B, C tips respectively and the value of Ks for B rip is about 20% less than A, C tips. 3. The surface roughness(Ra) improves significantly as the cutting speed(V) is increased and this effect was greater when V>100 m/min. On the other hand, Ra deteriorates as the feed rate(f) is increased and this trend was accelerated when f>0.3 mm/rev. With regard to the difference of Ra values among A, B, C tips, at V=226m/min, d=0.4mm, and f=0.31-0.61mm/rev, Ra values for B.C tips are about 17% less than tip A. 4. The experimental tool wear equations were derived for A, B, C tips and from these equations, the tool life($\textrm{T}_{\textrm{L}}$) baced on the I.S.O. criteria was calculated to be $\textrm{T}_{\textrm{L}}$<$\textrm{T}_{\textrm{LB}}$<$\textrm{T}_{\textrm{LC}}$ for both flank wear($\textrm{V}_{\textrm{B}}$) and boundary wear($\textrm{V}_{\textrm{N}}$). Hence, the coated tips are superior to the uncoated tip and tip C is considered to be the best. 5. The cutting resistance may be slightly reduced and the surface rounghness improved when the damper is used especially when V>100 m/min. Therefore this damping device is considered to be effective and practical. The experimental surface roughness equations were also derived. Based on the vibration test, it is established that the surface roughness improvement was the result of amplitude reduction made possible by the damper.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.3-17
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• 2003

This paper deals with the problems and their possible solutions in the development of finite element for analysis of shell. Based on these solution schemes, a series of flat shell elements are established which show no signs of membrane locking and other defects even though the coarse meshes are used. In the element formulation, non-conforming displacement modes are extensively used for improvement of element behaviors. A number of numerical tests are performed to prove the validity of the solutions to the problems involved in establishing a series of high performance flat shell elements. The test results reveal among others that the high accuracy and fast convergence characteristics of the elements are obtainable by the use of various non-conforming modes and that the ‘Direct Modification Method’ is a very useful tool for non-conforming elements to pass the patch tests. Furthermore, hierarchical and higher order non-conforming modes are proved to be very efficient not only to make an element insensitive to the mesh distortion but also to remove the membrane locking. Some numerical examples are solved to demonstrate the validity and applicability of the presented elements to practical engineering shell problems.

• 중환자간호학회지
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• 제11권2호
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• pp.51-62
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• 2018

Purpose : This study aimed to provide primary data for developing a program to enhance communication competence by identifying the patient-centered communication competency level of Intensive Care Unit (ICU) nurses and the related factors. Method : Data were collected from August 28th to October 8th, 2015, from 199 ICU nurses working in 30 tertiary hospitals. The study questionnaire included items assessing the patient-centered communication competency of ICU nurses, nursing organizational culture, types of communication, the Teamwork Measurement Tool, the Perceived Nursing Work Environment tool, and the Wong & Law Emotional Intelligence Scale. The collected data were analyzed using descriptive statistics, a correlation test, and a multiple regression. Results : The ICU nurses' mean score on patient-centered communication competency was 3.97 points. The factors influencing the patient-centered communication competency level of ICU nurses were professionalism (p =.002), innovation-oriented organizational culture (p =.015), and emotional intelligence (p<.001). These variables explained 42.2% of the total variance in the patient-centered communication competency of ICU nurses. Conclusion : These findings suggest the need for developing a patient-centered communication competency improvement program that focuses on improving ICU nurses' professionalism and emotional intelligence, and facilitates the creation of an innovation-oriented organizational culture.

• 대한기계학회논문집A
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• 제27권10호
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• pp.1728-1737
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• 2003

The vertical lathe is a very popular machine tool in modem manufacturing industries because of its small area of installation. The small installation area is highly desirable for the flexibility improvement of the manufacturing systems such as FMS, CIM, and IMS. The vertical lathe, however, has much taller height compared to the traditional horizontal lathe, and consequently more severe vibrations. In this study, the structure of a vertical lathe is analyzed to investigate the dynamic properties and further to establish some ideas of the design alteration for the improved dynamic stability even at the higher operating speed. The simulation model is implemented to apply those design alterations for the optimization. The result of this study is not only prosperous but also ready to be applied to the optimum design of various machine tool structures for the improved stability.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.216-222
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• 2021

Advances in technology have given educators a tool to empower them to assist with developing the best possible human resources. Teachers at universities prefer to use more modern technological advances to help them educate their students. This opens up a necessity to research the capabilities of cloud-based learning services so that educational solutions can be found among the available options. Based on that, this essay looks at models and levels of deployment for the e-learning cloud architecture in the education system. A project involving educators explores whether gement Systems (LMS) can function well in a collaborative remote learning environment. The study was performed on how Blackboard was being used by a public institution and included research on cloud computing. This test examined how Blackboard Learn performs as a teaching tool and featured 60 participants. It is evident from the completed research that computers are beneficial to student education, especially in improving how schools administer lessons. Convenient tools for processing educational content are included as well as effective organizational strategies for educational processes and better ways to monitor and manage knowledge. In addition, this project's conclusions help highlight the advantages of rolling out cloud-based e-learning in higher educational institutions, which are responsible for creating the integrated educational product. The study showed that a shift to cloud computing can bring progress to educational material and substantial improvement to student academic outcomes, which is related to the increased use of better learning tools and methods.

• 한국산업융합학회 논문집
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• 제20권4호
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• pp.265-273
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• 2017

Major industries in Gyeongnam area include robot and automobile manufacturing, shipbuilding, and aviation. According to the research, the mechanical part of the products has been advanced, but awareness over the improvement of quality of the software still lacks. The quality performance test presently conducted by the companies in Gyeongnam is mostly the manual performance test performed by the program manager. In order to systematize this and extend the range of using software testing tools, the current study intends to suggest the necessity for conducting a survey on demand to improve performance and securing testing tools such as measured data analysis. Accordingly, this study is going to investigate 33 companies in Gyeongnam related with software in each of the major business areas centering around the actual field and examine activities related to software quality. And after figuring out the current status of retaining testing tools, the study will suggest the ways to enhance recognition over software quality and propose ultimate solutions to solve the problems on the current stage by finding out how to share information as much as possible in order to lay the foundation for extending the range of activity for the sake of software quality.

• 한국정보통신학회논문지
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• 제18권12호
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• pp.3069-3078
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• 2014

본 연구에서는 다양한 수중무기폭발 체계 중 대표적인 비닉(庇匿) 무기체계인 기뢰를 중심으로 공격형 부설에 의한 억제 시 적함 탐지의 핵심이 될 자력계를 신규 Modeling & Simulation에 의해 성능 개선의 효과를 사전 검증한다. 또한, 신규 3축 자력계를 설계/제작/실험을 진행한 결과를 다룬다. 신규 자력계를 새로운 신형 수중무기체계에 적용하기 위해 상용 전자기장 수치해석 도구를 이용해 잠수함을 모델링하여 실 함정의 자기장특성을 예측한다. 실험의 마지막 단계로 축소 모형을 제작하여 실제 해상시험을 하지 않더라도 육상에서 성능검증 할 수 있는 방법을 제시한다.

• 한국산업정보학회논문지
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• 제24권1호
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• pp.31-38
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• 2019

본 논문에서는 초음파 응용 영상 기술의 다양한 임상 진단 응용이 가능한 파이프라인 회로 구성 방식을 가지는 빔포밍 프런트 엔드 플랫폼을 개발한다. 하드웨어 설계에서는 전력, 통합수준 및 복제 가능성이 중요한 확장 가능한 애플리케이션은 물론 압축 애플리케이션을 대상으로 한다. 펌웨어 디자인으로는 차세대 고수준의 합성 도구인 Vivado HLS 툴을 사용하여 최대의 생산성 향상으로 설계 생산성을 가속화하는 새로운 IP 및 시스템 중심 설계 환경 구축을 통하여 최적의 FPGA 병렬 처리 수준을 달성 하도록 구현하였다. 설계된 디지털 빔포머는 향후 시스템 사양의 재구성이나 변경시 적절한 수정 및 보완이 가능하고, 임의의 이미지 영역을 생성할 수 있는 스캔 데이터의 고속 관리 기능을 지원한다.