• 한국수학교육학회지시리즈E:수학교육논문집
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• 제21권2호
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• pp.331-345
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• 2007

본 연구에서는 중학생들이 수학 평가 결과를 어떻게 파지하는지를 탐구하고자 하였다. 이를 위해, 측정시기, 문항 유형, 성적, 평가요소 등을 학생들이 평가결과를 파지하는데 중요한 요인이라고 보고 이 변인들과 관련된 학생들의 평가결과 파지 유형을 분류하였다. 이를 토대로, 두 명의 연구 참여자를 선정하여 심층면담을 진행함으로써 그들의 평가에서 핵심적인 역할을 하는 요소가 무엇이며 그것이 향후에 어떤 형태로 파지되어 나타나는지를 분석함으로써 중학생들의 수학과 평가 결과의 파지 유형을 분석하였다.

• 한국압력기기공학회 논문집
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• 제19권1호
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• pp.36-43
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• 2023

Lots of researches have been conducted on in-vessel retention (IVR) to prevent or mitigate severe accident in nuclear power plants. Various methodologies were proposed and the external reactor vessel cooling was selected as a part of promising IVR strategy. In this study, the strategy is strengthened by enhancing the natural circulation performance through the adoption of insulation in the reactor cavity. A thermal analysis was carried out based on an assumed accident scenario and its results were used as boundary conditions for subsequent seven flow analysis cases. By comparing the natural circulation performance, effects of annular gaps and insulation shapes on the mass flow rate and flow velocity were quantified. The improvement in cooling performance can be reflected in actual design via detailed assessment.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.990-1001
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• 2004

The retention of a molten pool vessel cooled by internal vessel reflooding and/or external vessel reactor cavity flooding has been considered as one of severe accident management strategies. The present numerical study investigates the effect of both internal and external vessel mixed cooling on an internally heated molten pool. The molten pool is confined in a hemispherical vessel with reference to the thermal behavior of the vessel wall. In this study, our numerical model used a scaled-down reactor vessel of a KSNP (Korea Standard Nuclear Power) reactor design of 1000 MWe (a Pressurized Water Reactor with a large and dry containment). Well-known temperature-dependent boiling heat transfer curves are applied to the internal and external vessel cooling boundaries. Radiative heat transfer has been considered in the case of dry internal vessel boundary condition. Computational results show that the external cooling vessel boundary conditions have better effectiveness than internal vessel cooling in the retention of the melt pool vessel failure.

• 한국습지학회지
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• 제16권3호
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• pp.371-381
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• 2014

현재까지 국내에서 수질관리 정책이 점오염원 관리를 우선 시 하고 있다. 비점오염원은 배출특성, 배출지점 및 배출량의 파악에 매우 어려움이 있다. 이러한 비점오염 관리를 위해 다양한 비점오염저감시설들에 대한 개발 및 연구가 진행되고 있다. 비점오염시설의 평가를 위해 다양한 효율산정 방법들이 제시되고 있다. 본 연구에서는 강우 시 식생수로 모니터링 결과를 통해 체류시간이 저감효율에 미치는 영향에 대해 연구를 수행하였다. 또한 여러 가지 저감효율 산정 방법에 따른 차이를 비교하고자 하였다. 식생수로에서 체류시간에 따른 효율 분석 결과 체류시간이 길수록 저감효율도 높아지는 것으로 나타났다. 이는 식생수로의 안정적인 저감효율을 확보하기 위해선 충분한 체류시간이 확보 되어야 한다고 판단된다.

• 한국환경과학회지
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• 제14권10호
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• pp.937-944
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• 2005

Presently, aquatic plants are used for the water purification in inland water. This study was carried out to investigate the water purification effect of aquatic plants, Oenanthe javanica and Typha angustata, The experiment was conducted in outdoor flowing water was conducted for ten days, Water quality was measured in terms of water temperature, COD(chemical oxygen demand), SS(suspended solids), Total N, Total P. The results of field experimentation showed that hydraulic retention time was the earliest in July and August 2003, and there were not any particular changes of monthly water temperature in inflow water and outflow water. As we look at the changes taken place in inflow water and outflow water throughout the whole experiment period, the change of water quality in summer was salient, especially SS removal ratio showed distinguished change as $25\%$, when the pebble filter and aquatic were attached to it. The removal rate of COD, total N total P were $14,7\%,\;8\%\;and\;9\%$, respectively. In relating the length of water extension to the change in water quality, the water quality tended to get lower generally in proportion to hydraulic retention time.

• 환경영향평가
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• 제20권6호
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• pp.815-821
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• 2011

This study aims to estimate the biological decomposition capacity of MPC(Microorganism Porous-Concrete). MPC has specific surface area formed by inside pores, and bio compound was added to those pores to reduce pollutants loading. To evaluate the water purification capacity of MPC, we carried out the comparative studies using different media types [GPC(General Porous-concrete), CPC(Compound porous-concrete), LPC(Lightweight aggregate porous-concrete)] under the condition of CFSTR, and different retention times (30, 60 and 120 min). We also estimated the purification capacity of MPC under different concentrations of pollutant loadings. The MPC showed higher efficiency in water purification function than other conventional porous concretes with efficient decrease rates of SS, BOD, COD, and nutrient concentrations. In the comparison experiment for different retention times, MPC showed the highest removal efficiency for all tested pollutants in the longest retention time(120 min). In the long period test, the removal efficiencies of MPC concrete were high until 100 days after the set up of the operation, but began to decrease. Outflow flux was invariable compared with inflow flux so that extra detention time for media fouling such as back washing is not needed. But the results suggested that appropriate management is necessary for long-term operation of MPC. As the final outcome, MPC using bio organisms is considered to be efficient for stream water purification when they used as substrates for artificial river structure.

• Advances in materials Research
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• 제5권1호
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• pp.21-34
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• 2016

Fire is one of the most destructive powers to which a building structure can be subjected, often exposing concrete elements to elevated temperatures. The relative properties of concrete after such an exposure are of significant importance in terms of the serviceability of buildings. Unraveling the heating history of concrete and different cooling regimes is important for forensic research or to determine whether a fire-exposed concrete structure and its components are still structurally sound or not. Assessment of fire-damaged concrete structures usually starts with visual observation of colour change, cracking and spalling. Thus, it is important to know the effect of elevated temperatures on strength retention properties of concrete. This study reports the effect of elevated temperature on the mechanical properties of the concrete specimen with polypropylene fibres and cooled differently under various regimes. In the heating cycle, the specimen were subjected to elevated temperatures ranging from $200^{\circ}C$ to $800^{\circ}C$, in steps of $200^{\circ}C$ with a retention period of 1 hour. Then they were cooled to room temperature differently. The cooling regimes studied include, furnace cooling, air cooling and sudden cooling. After exposure to elevated temperatures and cooled differently, the weight loss, residual compressive and split tensile strengths retention characteristics were studied. Test results indicated that weight and both compressive and tensile strengths significantly reduce, with an increase in temperature and are strongly dependent on cooling regimes adopted.

• 대한치과교정학회지
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• 제41권3호
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• pp.154-163
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• 2011

본 연구는 교합 상태를 객관적이고 정량적으로 평가하기 위해 개발된 American Board of Orthodontics objective grading system (ABO-OGS)을 이용하여 교정치료 후 나타나는 재발 경향을 평가하고 이에 영향을 줄 수 있는 요소들과의 상관관계를 알아보고자 시행되었다. 부산대학교, 경희대학교와 단국대학교 치과병원 교정과에서 포괄적 교정치료를 받은 환자 중 치료종료 후 2년 이상의 유지기간을 갖는 80명의 환자를 대상으로 초진 시(T1)의 peer assessment rating (PAR) index, 치료 후(T2)와 유지 후(T3) 시기의 ABO-OGS를 측정하여 T2와 T3 간의 변화 양상을 각 항목별로 측정하였고, 나이, 성별, Angle 분류, 발치 여부, 유지기간, 초진 시의 상태와의 상관관계를 조사하기 위해 다중 회귀분석을 시행하여 다음과 같은 결과를 얻었다. T2 시기와 비교하여 T3 시기에 ABO-OGS의 7개 항목 중 치아 배열(alignment)은 악화되었으며, 교합 접촉(occlusal contact)과 치간 접촉(interproximal contact)은 개선되었고, 나머지 4개의 항목에서는 유의한 차이가 없었다. 다중 회귀분석을 시행한 결과, 유의한 회귀모형은 치아 배열(alignment), 교합 관계(occlusal relationship), 수평피개(overjet), 치간 접촉(interproximal contact) 항목이었으나, 회귀 모형들의 설명력이 낮았으며, 연령, 성별, Angle 분류, 발치 여부, 유지기간, 초진시의 상태(initial PAR index, T1)는 T2 시기와 T3 시기의 ABO-OGS 변화량을 설명하는 데 큰 영향을 미치지는 않는 것으로 보인다.

• 산경연구논집
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• 제14권12호
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• pp.23-31
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• 2023

Purpose: The primary objectives of this research are: (1) To examine the current situation of employee welfare in diverse workplace settings. (2) To explore and identify the different challenges that affect employees' overall well-being. (3) To examine and establish the importance of consultation as a strategic tool in addressing these challenges and enhancing employee welfare. Research design, data and methodology: The first step of the research design is the identification of databases, search terms, and filters. A thorough search will be conducted across respectable academic databases, journals, and pertinent sources using keywords and controlled vocabulary about consultation, employee welfare, and related concepts. The next step is full-text assessment, which verifies compliance with the research question and assesses the caliber of the methodology. Results: According to the previous evidence, the significant benefits of effective consultation for employee welfare have been highlighted: 1. positive impact on productivity in the workplace, 2. Effective consultation Improves employee's engagement, 3. Effective consultation Increases employee retention, and 4. Effective consultation facilitates trust in a corporate communication. Conclusions: The study has identified four main advantages: enhanced productivity, enhanced engagement, increased retention, and enhanced trustbuilding. These findings provide insightful information for practitioners looking to foster positive workplace cultures and improve organizational success.

• 환경영향평가
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• 제32권2호
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• pp.112-122
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• 2023

오염 토양의 생태적 기능을 회복하고 토양이 제공하는 생태적 서비스를 최대화하기 위해서는 오염물질에 의한 독성이나 위해성 외에도 토양생태계의 기능적인 측면인 생물서식처, 영양분 순환, 완충작용등과 같은 토양의 건강성을 고려하여야 한다. 본 연구에서는 정화토양의 건강성을 정량적으로 평가하는 방법을 제시하고 세척처리 및 토양경작처리 토양에 적용하여 제안한 평가방법의 적용 가능성을 살펴보았다. 토양의 생산성, 서식처, 수분보유능, 물질순환능, 완충능, 탄소보유능 등으로 토양 건강성 평가항목을 선정하고, 평가지표로 식물 성장, 지렁이 성장, 수분보유능, 미생물활성도, 양이온교환용량, 유기물함량 등을 활용하였다. 본 연구결과 오염물질 정화 후에도 토양 건강성이 온전히 회복되지 않는 것으로 나타났는데, 오히려 세척 토양의 경우와 같이 정화 전보다 건강성이 떨어지는 경우도 발생하였다. 반면에 유류 오염으로 인한 토양질의 변화는 크게 없는 반면, 토양건강성은 나빠지는 것으로 나타났으며, 경작처리 후 다소 개선된 토양질과는 달리, 토양 건강성은 여전히 회복하지 못한 것으로 나타났다. 따라서 본 연구 결과 오염과 정화과정 중에 토양의 정화 효과를 평가할 경우에는 토양질과 토양건강성을 함께 고려하는 것이 바람직함을 보여 주었다. 정화 토양의 지속 가능한 이용 및 생태계 서비스 증진을 위해 본 연구에서 제시된 정화 토양의 건강성 평가 방법이 유용하게 활용될 수 있을 것으로 기대된다.