• 한국재료학회지
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• 제20권11호
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• pp.581-585
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• 2010

High strength sheet steels for automobile are seriously compromised by hydrogen embrittlement. This issue has been continuously studied, but the field of interest, which lies between microstructural characteristics and hydrogen behavior with hydrogen charging, has not yet been thoroughly investigated. This study was done to investigate the behavior of hydrogen according to the hydrogen volume fraction on 590MPa grade DP steels, which are developed under hydrogen charging conditions as high strength sheet steels for automobiles. The penetration depths and the mechanical properties, according to charging conditions, were investigated through the distribution of micro-hardness and the microstructural observation of the subsurface zone. It was found that the amount of hydrogen trapping in 590MPa DP steels was related to the austenite volume fraction. It was confirmed that the distribution of micro-hardnesses according to the depth of the subsurface zone under the free surface showed the relationship of the depth of the hydrogen saturation between the charging conditions.

• 대한간호학회지
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• 제46권2호
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• pp.226-237
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• 2016

Purpose: The purpose of this qualitative study was to explore the workplace bullying experience of Korean nurses. Methods: Participants were twenty current or former hospital nurses who had experienced workplace bullying. Data were collected through focus group and individual in-depth interviews from February to May, 2015. Theoretical sampling method was applied to the point of theoretical saturation. Transcribed interview contents were analyzed using Corbin and Strauss's grounded theory method. Results: A total of 110 concepts, 48 sub-categories, and 17 categories were identified through the open coding process. As a result of axial coding based on the paradigm model, the central phenomenon of nurses' workplace bullying experience was revealed as 'teaching that has become bullying', and the core category was extracted as 'surviving in love-hate teaching' consisting of a four-step process: confronting reality, trial and error, relationship formation, and settlement. The relationship formation was considered to be the key phase to proceed to the positive settlement phase, and the participants utilized various strategies such as having an open mind, developing human relationships, understanding each other in this phase. Conclusion: The in-depth understanding of the workplace bullying experience has highlighted the importance of effective communication for cultivating desirable human relationships between nurses.

• 한국환경농학회지
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• 제26권4호
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• pp.294-299
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• 2007

Natural gypsum has been used as a soil amendment in the United States. However, flue gas desulfurization (FGD)-gypsum has not traditionally been used for agricultural purpose although it has potential benefit as a soil amendment. To expand use of FGD-gypsum for agricultural purpose, the effect of FGD-gypsum on soil chemical properties was investigated in the field scales. Application rates for this study were 0 (control), 1.1, and 2.2 Mg ha-1 of FGD-gypsum. After two year application, the soil samples were taken to 110 cm depth and sub-sampled at 10 cm intervals. The heavy metal contents in FGD-gypsum were lower than ceiling levels allowed by regulations for land-applied biosolids. Soil pH was not largely affected by FGD-gypsum application. Although degree of calcium (Ca) saturation in surface horizons increases only slightly with respect to the control, there is a clear decrease in exchangeable aluminum (Al). FGD-gypsum clearly increases the soil electrical conductivity (EC) with increasing application rate. Water-soluble Ca and sulfate is increased with FGD-gypsum application and these ions moved to a depth of at least 80 cm after only 2 years. We conclude that surface application of FGD-gypsum can mitigate toxicity of Al and deficiency of Ca in subsoil of acid soil.

• 한국간호교육학회지
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• 제28권2호
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• pp.167-178
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• 2022

Purpose: South Korea has expanded its accelerated second-degree Bachelor of Science in Nursing program to resolve its supply-demand imbalance in nursing, although how these students are adapting to and performing in college after admission remains unclear. Therefore, this study aimed to conduct an in-depth exploration of how Korean accelerated second-degree Bachelor of Science nursing students interact with society and adapt to college life for establishing further supportive educational policies and programs. Methods: Participants comprised 20 South Korean accelerated second-degree Bachelor of Science in Nursing students. The data were collected via online or offline in-depth interviews and analyzed using Strauss and Corbin's grounded theory and by applying a constant comparative method to achieve theoretical saturation. Results: The core category, derived using open, axial, and selective coding, was "process of the uncharted journey toward a new dream." The participants' college adaptation processes were found to involve three phases: trial and error, adjustment, and acceptance and integration. Conclusion: These findings can be used to develop, apply, test, and improve various support programs for accelerated second-degree Bachelor of Science in Nursing students and to advance the nursing profession by nurturing a workforce with diverse academic backgrounds and faster college life adaptation.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.311-312
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• 2023

In this study, porous concrete with improved functionality was developed by using superabsorbent polymer (SAP) to provide rooting space for plants. The depth of settlement and mass change according to the substitution and addition rate of SAP were determined by investigating the functional performance of SAP and the volume change upon saturation. Test results indicated the depth of penetration settlement increased as the substitution rate of SAP increased, but the mass change could not be confirmed as the addition rate of SAP increased. The instability of the specimens due to the excessive volume change of SAP, as well as the osmotic pressure phenomenon according to the pH concentration, were identified as the cause. Therefore, future studies are needed to investigate the appropriate substitution and addition rate of SAP, as well as to reduce the osmotic pressure phenomenon according to the pH concentration, which would contribute to the improvement of the functional performance of vegetation concrete.

• 한국수자원학회논문집
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• 제36권6호
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• pp.1035-1046
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• 2003

TOPMODEL의 지하수면길이 분포에 대한 예측능력을 평가하기 위해 2개 기본가정과 지하수면깊이에 대한 지배방정식을 검증하였다. 검증에는 토양두께가 얇은 급경사 사면의 수문관측과 토양조사 자료를 이용하였다. 조사사면에서 지하수면반응과 토양의 수리적 특성은 지형경사와 평행하는 수리경사, 지하수면깊이에 지수함수적으로 감소하는 투수량계수 등과 같은 TOPMODEL의 기본가정과 일치하였다 토양의 투수량계수감소율(f)과 토성은 지표부터 깊이 0.3m까지 사면전체에서 공간적으로 균질하지만, 토성과 f의 수직적인 변화로 깊이 0.3m 아래부터 공간적으로 불균질한 특성을 보인다. 조사사면에서 TOPMODEL의 지배방정식은 f값이 공간적로 균질한 깊이의 지하수면깊이 분포를 예측하는데 적용할 수 있는 것으로 나타났다.

• 한국재료학회지
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• 제3권1호
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• pp.58-64
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• 1993

고탄소 Dr-Ti 합금강의 회전접촉 피로마모실험에서 실험조건에 따라 다르게 변화하는 subsurface zone의 가공경와의 정도를 잔류응력의 분포로서 조사하였다. 시험전 표면잔류응력은 마모특성에 영향을 주지 못하였고, 접촉응력과 회전속도가 증가할수록 표면 잔류응력은 감소하여 갔으나 subsurface zone내의 최대압축잔류응력은 증가하였고, 그의 포화깊이는 깊었다. 이들 실험결과와 이론적 전단응력의 분포와의 관계에 관하여 검토하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1151-1155
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• 2010

Frost depth is one of important factors to design roadway structure, and it can be estimated with numerical simulation on thermal distribution through subgrade soils. Thermal conductivity is a key parameter for accurate prediction on thermal distribution, but there are few studies on thermal conductivity of subgrade soils in Korea. Thermal conductivity can be affected by several factors such as dry density, moisture content, and saturation degree based on previous researches. Two empirical equations to estimate thermal conductivity are applied to access the accuracy of these equations with experimental data. Results indicate that the equation can be used to estimate thermal conductivity with proper quartz fraction.

• 한국안전학회지
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• 제18권1호
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• pp.89-93
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• 2003

The failure of rock slopes were influenced by weathering, which causes change in the shear strength. The weathering is also directly related to slaking and swelling characteristics. In the paper, the core of diameter loom was obtained by digging on rock slope of Kong-ju in Korea and then EDX(Energy Dispersive X-ray spectrometer) analysis was carried out to verified element of chief rock-forming minerals. Uniaxial compression tests, slaking tests, and point load test are performed to study engineering characteristics of conglomerate and red shale. As a results of slaking test, slaking index of conglomerate indicate range of 85.11-99.58 and shale indicate 58.37-99.23. Therefore, it is recognized that the resistance of shale to weathering decreases in shallow depth and it greatly influences the strength of rock. The result of uniaxial compression test and Point load test show that the strength of sedimentary such as conglomerate and red shale has an influence on both weathering and saturation.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.8-13
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• 2001

In the turning process, the feed is usually selected by a machining operator considering workpiece, cutting tool and depth of cut. Even if this selection can avoid power saturation or tool breakage, it is usually conservative compared to the capacity of the machine tools and can reduce the productivity significantly. This paper proposes a selection method of the feed and the reference cutting force based on MRR(material removal rate), maximum spindle power and specific energy. In order to estimate and control cutting force accurately in transient and steady state, this study utilizes a synthesized cutting force estimation method and a Fuzzy controller. The experimental results present that these systems can be useful for the FMS(flexible manufacturing system) and unmanned automation system.