• 한국지반공학회논문집
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• 제15권5호
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• pp.125-139
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• 1999

풍화잔적토는 불교란 시료를 채취하기가 곤란하기 때문에 전단강도를 산정하는데 있어서 어려움을 겪고 있다 본 연구에서는 직접 전단시험용 불교란 시료를 용이하게 채취하기 위해서 슈 장착 직접 전단상자를 개발하였으며, 성공적으로 불교란 시료를 채취할 수 있었다. 채취된 분교란 시료의 직접 전단시험을 통해서 포화조건에 따른 전단강도의 변화를 규명하였다. 그리고 교란에 따른 풍화잔적토의 전단거동을 규명하기 위해서 정적시료 성형장치를 제작하였고, 자연함수비 상태에서는 교란에 따른 강도저하가 나타나지만, 수침시에는 강도가 유사함을 확인하였다. 불교란 시료에 대해서 직접전단시험과 삼축압축시험시의 강도를 비교한 결과, 직접 전단시험시 수침시료의 강도가 삼축압축시험의 결과와 유사한 경향을 나타내었다. 그리고 대상 붕괴사면에 대한 역해석을 수행한 결과, 슈 장착 직접 전단상자를 이용하면 풍화잔적토 사면에서의 전단강도 산정이 가능하리라고 판단되었다.

• 농약과학회지
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• 제19권1호
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• pp.1-4
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• 2015

잔류성 유기오염물질인 과불화합물 중 perfluorooctanesufonic acid (PFOS)와 perfluorooctanoic acid (PFOA)의 잔류분석은 환경부 "잔류성 유기오염물질 공정시험기준"에 따라 hydrophilic-lipophilic balance (HLB) solid phase extraction (SPE) 전처리 후 LC-$MS^n$를 이용해 정량 분석하고 있다. 본 연구에서는 환경부 설정 공정시험법에 따라 농업용수 전처리 후, 시험법에서 제거하지 못한 미지의 불순물을 Envi-Carb$^{TM}$을 통해 회수율에 영향을 주지 않고 손쉽게 제거하였다. 또한, 과불화합물 분석에 사용되는 LC-$MS^n$ 중 quadrupole-time-of-flight mass spectrometry (qTOFMS)에서 측정된 PFCs의 정량한계를 평가한 결과, 시험에 사용된 장비간 정량한계 편차가 크게 관찰되었으나, 시험대상 장비 모두 농업용수 중 ng/L 수준으로 잔류하는 과불화합물의 정밀 잔류분석에 사용가능 한 것으로 확인되었다.

• 한국지반신소재학회논문집
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• 제17권3호
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• pp.9-18
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• 2018

연약지반 설계에 중요한 지반정수는 압축지수($C_c$)이며, 현장의 압밀침하량 및 압밀침하속도를 산출하는데 필요하다. 이러한 압축지수 산정은 실내압밀시험을 통해 얻어지는데, 실내압밀시험에서는 반드시 시료교란이 발생하며, 이러한 교란현상을 보정하기 위하여 Schmertmann(1955)이 제시한 보정 압축지수 산정방법이 일반적으로 사용되고 있다. 그러나 최근 시료 샘플링기술의 발전과 국내 지반조건 등이 Schmertmann이 제시한 것과 상이하므로 이에 대한 검증이 필요하다. 이에 본 연구에서는 저소성 실트(ML), 저소성(CL) 및 고소성 점토시료(CH)에 대하여 교란도를 변화시켜 압밀시험을 실시하여 각각의 압밀곡선의 교차 간극비를 평가하였다. 시험결과 저소성 실트(ML)의 경우 $0.521e_0$, 저소성 점토(CL)의 경우 $0.404e_0$, 고소성 점토(CH)의 경우 $0.458e_0$로 산정되어, Schmertmann이 제시한 $0.42e_0$의 보정값과 다른 결과를 확인하였으며, 흙의 종류에 따른 소성지수(PI)를 활용한 보정식을 제안하였다. 그러나 본 연구결과는 한정된 지역에서의 시험결과이므로 흙의 소성도에 따른 압축지수 보정방법을 제시하기 위해서 다양한 국내 점토에 대한 후속연구가 필요할 것으로 판단된다.

• International Journal of Computer Science & Network Security
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• 제22권9호
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• pp.7-14
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• 2022

COVID-19 has caused a global disturbance, increased anxiety, and panic, eliciting diverse reactions. While its cure has not been discovered, new infection cases and fatalities are being recorded daily. The focus of the present study was to analyze the reaction of gifted undergraduate students on social media during the quarantine period of the COVID-19. A special group of gifted students, who joined the program of attracting and nurturing talents at the University of Jeddah, University students as were the target sample of this study. To analyze online reactions during the pandemic; the choice of university students was arrived at as they are perceived to be gifted academically. Hence, the analysis of the impacts on their behavior on social media use is imperative. This study presented accurate and consistent data on the effects of social media using Twitter platforms on gifted students during the quarantine occasioned by the COVID-19 pandemic. The behavior of learners due to during the use of social media was extensively explored and results analyzed. The study was carried out between April and May 2020 (quarantine period in Saudi Arabia) to establish whether the online behavior of gifted students reflects positive or negative feelings. The methods used in conducting this study the research were online interviews and scraping participants' Twitter accounts (where most of the online activities and studies take place). The study employed the Activity theory to analyze the behavior of gifted students on social media. The sample size used was 60 students, and the analysis of their behavior was based on Activity theory Overall, the results showed proactive, positive behavior for coping with a challenging situation, educating society, and entertaining. Finally, this study recommends investing in gifted students due to their valuable problem-solving skills that can help handle global pandemics efficiently.

• 지질공학
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• 제31권3호
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• pp.333-342
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• 2021

본 연구에서는 기존의 전통적인 다짐관리방법의 문제점을 보완하고자 TDR(Time Domain Reflectometry)을 이용하여 지반의 함수비와 건조단위중량을 측정하는 연구를 수행하였다. Flat TDR 시스템은 지반의 교란을 일으키기 않는 장비로써 측정값을 검증하기 위하여 주문진표준사 외 7개소의 현장대상 지반의 시료에 대하여 건조밀도와 함수비를 측정하였다. 함수비구간은 3, 6, 9, 12, 15, 18%의 6개 구간으로 나누어 측정을 하였으며 실험결과는 통일분류법에 따라 확인하였다. 실내실험 결과, 함수비는 SP시료의 경우 약 0.7%, SM시료의 경우 약 1.3%의 오차를 보였다. 또한 건조단위중량은 SP시료의 경우 약 7%, SM시료의 경우 약 5%의 오차를 확인하였다. 이는 점토나 자갈을 제외한 모래 또는 실트질 모래 지반에서는 안정적인 값을 도출함을 확인할 수 있었다. 실험 결과를 통하여 Flat TDR 시스템의 측정값이 기존의 전통적인 다짐관리방법과 유사한 값을 도출하는 것을 확인할 수 있었고 이는 빠른 시공성과 경제성을 필요로하는 건설현장에서 Flat TDR 장비가 적합하다는 것을 판단할 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.71-78
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• 2000

SHANSEP method involves the consolidation to stresses in excess of the preconsolidation pressure in order to overcome sample disturbance effect. The concept of SHANSEP is based on an approach to laboratory test which attempts to reproduce the in-situ conditions more closely than is possible in routine tests and evaluates normalized strength parameters for the soil as a function of OCR. But SHANSEP method can be applied only to fairly uniform clay deposits, and is unsuitable for a random deposit. In this study, CK/sub o/U triaxial compression test and incremental loading consolidation test were performed for the application of SHANSEP method on Yangsan clay. During the K/sub o/-consolidation, triaxial specimens were consolidated to stress equal to two times the in-situ vertical effective stress. And for overconsolidated condition, the specimens were swelled to a known vertical effective stress in order to have the desired OCR. With the results of CK/sub o/U triaxial compression test using the block samples, the relationship between c/sub u//σ/sub vc/' and OCR on Yangsan clay was established. For evaluating the undrained shear strength of Yangsan clay with depth, CK/sub o/U triaxial compression test was performed using the piston samples taken from Yangsan site. And also undrained shear strength was analyzed from the in-situ test such as Cone Penetration Test(CPT), Dilatometer Test(DMT), and Field Vane Test(FVT) and was compared with that of CK/sub o/U triaxial compression test.

• 성인간호학회지
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• 제27권4호
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• pp.428-437
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• 2015

Purpose: The aim of this study was to describe health status and to identify the factors related to health behavior in older adults in South Korea. Methods: A cross-sectional survey was conducted with a convenience sample of 186 older people (mean age =68.2yrs, 65.1% Female) registered at one senior center. Data were collected by self-report questionnaires or through face to face interview. The instruments were the Modified Health Behavior Assessment Scale, Stanford Research Instruments for Chronic Disease, Self-Efficacy, SOF Frailty Index and Quality of life questionnaire. The data were analyzed using t-test, ANOVA, Pearson's correlation, and stepwise multiple regression. Results: 58.6% older adults perceived their health status positively. Education level and economic status were significantly related to health behaviors of older adults. Self-rated health, sleep, stress, quality of life, health distress, depression, and frailty were significantly correlated with the health behaviors of older adults. Frailty, education level, and sleep disturbance were the significant factors predicting the health behaviors. Conclusion: The findings from this study suggest that nurses should take into consideration education level of older adults to promote their health behaviors and health promotion program which focuses on maintaining the quality of sleep and preventing frailty.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.614-619
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• 2004

The line-of-sight (LOS) stabilization system is a precision electro-mechanical gimbals assembly for rejecting vibration to isolate the load from its environment and point toward the target in a desired direction. This paper describes the design of gimbals system to reject the disturbance and to improve stabilization. To generate movement commands for the actuators in the stabilization system, the control system uses a sensor of angular rotation. The controller is a DSP with transducer and actuator interfaces. Unknown parameters of the gimbals are estimated using the signal compression method. The cross-correlation coefficient between the impulse response from the assumed model and the one from model of the gimbals is used to obtain the better estimation. And SMCPE (sliding mode control with perturbation estimation) is used to control the gimbals. SMCPE provides robustness of the control against the modeling deficiencies and unknown disturbances. In order to compare the performance of SMCPE with the classical SMC, a sample test result is presented.

• 성인간호학회지
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• 제22권5호
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• pp.457-465
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• 2010

Purpose: This study was conducted to examine the degrees of depression and activities of daily living (ADLs), and to identify factors that predict depression in elderly patients. Methods: The sample was149 patients (80% female; mean age 79.1) from three geriatric hospitals located in small cities and who agreed to participate in the study. Data were collected by staff nurses involved in direct patient care from October to September 2009. The level of depression was measured on a daily basis for seven days using a 13-item scale. Patients' ADLs was measured using a modified 10-item Bathel ADLs scale. Data were analyzed using SPSS/WIN 17.0. Results: Mean depression score was $10.05{\pm}4.77$ out of 26 points and about 27% was assessed as depressed with more than 13 points. Multiple regression analysis showed that low educational level, absence of spouse and fewer family visits predict depression. In addition, low ADLs and sleep disturbance predict depression. Conclusion: Nursing care providers need to be concerned about ADLs of older patients and should develop nursing activity programs to increase their in-hospital physical activities. It is also important care for older patients' sleep and encourages family visits to decrease their depression.

• The Korean Journal of Ecology
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• 제19권4호
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• pp.305-320
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• 1996

It is necessary to obtain information about the productivity of the human-influenced forest and to understand the consumption of biomass resources in secondary forest in order to examine the resource flux by human activity in rural landscape. Thus the aims of this study were to elucidate the biomass and their use of secondary Pinus densiflora forests and to discuss sustainable utilization of secondary forests in rural landscape system. This study was carried out in Yanghwa-ri, Kongjugun, Chungcheongnam-do, central Korea. The changes of growth rate and aboveground biomass of a pine forest for 2 years were analyzed to understand forest management regimes in rural pine forests. Through allometric equations deduced from 25 sample trees, biomass was estimated. The biomass increase of pine forest was approximately 16.36 t/ha/yr in the unexploited stand and 12.24 t/ha/yr in the exploited stand. These were nearly equal to those of natural pine forests in central Korea. This result proved that human-influenced pine forest in rural landscape as well as the natural one has high potentiality to provide forest products. Making graveyard in forest-land was the important disturbance and land-use which currently occurring in rural landscape in the study area. Finally, we presented some forest management for stutainable and positive uses of secondary forests as one of the local energy resources in terms of the holistic landscape-ecological view.