• 공업화학
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• 제16권4호
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• pp.513-518
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• 2005

혼합비율 및 반응온도의 변화에 따른 ZnO가 첨가된 PVC와 PS의 혼합 열분해 특성에 관한 연구를 TG와 GC-MS를 이용하여 수행하였다. 본 연구로부터 혼합물에 있어서 PS의 양이 증가할수록 액상 생성물은 증가하였으며 기상 생성물은 감소함을 알 수 있었다. 또한 ZnO의 첨가량이 증가할수록 기상 생성물과 염화수소의 발생량은 감소하였으며 염화수소의 발생 억제 및 액상 생성물의 최대수율을 얻기 위한 최적의 반응온도는 $500^{\circ}C$임을 알 수 있었다.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.301-309
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• 2016

Background: A contamination screening process for the local population in radiation emergencies is discussed. Materials and Methods: We present an overview of the relevant Korean governmental regulations that underpin the development of an effective response system. Moreover, case studies of foreign countries responding to mass casualties are presented, and indicate that responses should be able to handle a large demand for contamination screening of the local public as well as screening of the immediate victims of the incident. Results and Discussion: We propose operating procedures for an off-site contamination screening post operated by the local government for members of the public who have not been directly harmed in the accident. In order to devise screening categories, sorting strategies assessing contamination and exposure are discussed, as well as a psychological response system. Conclusion: This study will lead to the effective operation of contamination screening clinics if an accident occurs. Furthermore, the role of contamination screening clinics in the overall context of the radiation emergency treatment system should be clearly established.

• 한국해양공학회지
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• 제24권3호
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• pp.21-30
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• 2010

This study presents a numerical simulation of sea water-exchange as a preliminary accessing tool of water quality in the protected shore behind a overtopped breakwater. The overtopped breakwater is taken into account for a safe swimming and beach protection. The overtopping rate is calculated by empirical models and the consequent currents, known as wave-induced currents, are calculated under the conditions of H.W.O.S.T and L.W.O.S.T. The rate of sea water exchange is used to evaluate the characteristics of sea water exchange and calculated through the simulation processes such as advective discharging through the outlets and random-walking diffusion of particles released within a basin. The numerical results show that the overtopped waves sufficiently improve the water exchange without healthless stagnation of contaminated mass and the consequent currents are not too strong for swimming.

• 한국가스학회지
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• 제20권1호
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• pp.23-28
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• 2016

환경 친화적 자동차는 우리나라 정부가 추구하는 저탄소 녹생 성장 전략의 상징이어 왔다. 최근 정책 추세에 맞추어, 새로운 LPG 충전소가 많이 지어지고 있다. 하지만 대규모 가스 저장시설에서의 안전사고는 사회적으로 막대한 인명 피해와 재산 피해를 야기시켜 왔다. 이 논문에서는, LPG 충전소에서 안전사고를 사전에 예방하기 위하여 설치방법에 따라 경제적 분석을 실시하였다. 분석결과, 지하 저장소는 그 유지관리 및 효율적인 토지이용 면에서 긍정적인 것으로 나타났다.

• 디지털융복합연구
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• 제17권11호
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• pp.225-232
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• 2019

본 연구는 재난 상황 발생 후 이재민들에게 임시 주거용 공간을 손쉽게 제공하기 위한 임시 주거용 프리패브 모듈라 구조를 제안하기 위해서 진행하였다. 이를 위해 관련 디자인 개념 및 실행을 위해 국내에 등록된 조립식 구조물이나 프리패브 구조와 관련된 다양한 특허를 검색하고 수집하였으며, 이를 특성별로 분류하였다. 결과적으로 임시 주거용 프리패브 모듈라 구조의 공간은 "확장성", "조립 및 해체의 용이성", "빌트인 구조", 그리고 "에너지 효율성"과 같은 추가적인 주요 요인에 대해서도 고려해야 하며, 각 사례는 "세부 조립 모듈형", "모듈형 확장형", "공간 유닛 확장형"의 3가지의 형식으로 구분되었다. 향후 연구에서는 해외 특허를 대상으로 다양한 사례를 수집하고 분석할 예정이며, 이를 통해 가능한 낮은 생산 단가로 양산 및 제공할 수 있도록 구체적인 구현 방법에 대해서도 제안하고자 한다.

• Smart Structures and Systems
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• 제2권2호
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• pp.127-140
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• 2006

In this study, a wavelet-based covariance-driven system identification technique is proposed for damage assessment of structures under ambient excitation. Assuming the ambient excitation to be a white-noise process, the covariance computation is shown to be able to separate the effect of random excitation from the response measurement. Wavelet transform (WT) is then used to convert the covariance response in the time domain to the WT magnitude plot in the time-scale plane. The wavelet coefficients along the curves where energy concentrated are extracted and used to estimate the modal properties of the structure. These modal property estimations lead to the calculation of the stiffness matrix when either the spectral density of the random loading or the mass matrix is given. The predicted stiffness matrix hence provides a direct assessment on the possible location and severity of damage which results in stiffness alteration. To demonstrate the proposed wavelet-based damage assessment technique, a numerical example on a 3 degree-of-freedom (DOF) system and an experimental study on a three-story building model, which are all under a broad-band excitation, are presented. Both numerical and experimental results illustrate that the proposed technique can provide an accurate assessment on the damage location. It is however noted that the assessment of damage severity is not as accurate, which might be due to the errors associated with the mode shape estimations as well as the assumption of proportional damping adopted in the formulation.

• Smart Structures and Systems
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• 제24권1호
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• pp.1-14
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• 2019

Transmission tower-line system is one of most critical lifeline systems to cities. However, it is found that the transmission tower-line system is prone to be damaged by earthquakes in past decades. To mitigate seismic demands, this study introduces a tuned-mass damper (TMD) using superelastic shape memory alloy (SMA) spring for the system. In addition, considering the dynamic characteristics of both tower-line system and SMA are affected by temperature change. Particular attention is paid on the effect of temperature variation on seismic behavior. In doing so, the SMA-TMD is installed into the system, and its properties are optimized through parametric analyses. The considered temperature range is from -40 to $40^{\circ}C$. The seismic control effect of using SMA-TMD is investigated under the considered temperatures. Interested seismic performance indices include peak displacement and peak acceleration at the tower top and the height-wise deformation. Parametric analyses on seismic intensity and frequency ratio were carried out as well. This study indicates that the nonlinear behavior of SMA-TMD is critical to the control effect, and proper tuning before application is advisable. Seismic demand mitigation is always achieved in this wide temperature range, and the control effect is increased at high temperatures.

• 한국지진공학회논문집
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• 제26권4호
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• pp.157-164
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• 2022

The TMD has a simpler structure than other vibration control devices and shows excellent control performance for the standardized vibration occurring in the structure. However, when the vibration cycle of the structure coincides with the vibration cycle of the TMD due to the sudden external loads, the off-tuning occurs, which threatens the structure while increasing the vibration width of the TMD. Therefore, Electromagnetic Tuned Mass Damper (ETMD) was developed as a semi-active TMD that prevents off-tuning while exhibiting excellent control performance like TMD. To verify the control performance of the developed ETMD, the bending behavior control performance evaluation experiment using a simple beam bridge was performed. The experimental method compared the mutual control power by experimenting with the existing TMD method and the developed ETMD under nine excitation frequency conditions. As a result, it was confirmed that the control effect of ETMD was about 4.85% higher than that of TMD at 3.02Hz, which generates the maximum displacement in the simple beam bridge. Also, the off-tuning occurred in some excitation conditions when using TMD, although the off-tuning did not occur when using ETMD. Therefore, the excellent control performance of the ETMD developed in this study was verified.

• 한국전기전자재료학회논문지
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• 제36권1호
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• pp.42-48
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• 2023

Abstract: In this study, an induction heating system using resonance is developed to remove remaining moisture and contaminations which could be generated during fabricating secondary batteries. This system is composed of power supply and induction coil. Power supply needs an oscillator, zero crossing detection, frequency tracking function, and induction coil needs a dummy coil to obtain a uniform temperature distribution. It is very important to obtain a uniform heating temperature distribution of battery cell case in the induction heating system before pouring electrolyte into battery cell. Experimental results show a temperature distribution deviation of below 1℃ in the external position of battery cell cases. As well, the temperature of battery cell itself shows distribution of 40℃±3℃.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.159-159
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• 2022

Soil represents a substantial component within the global carbon cycle and small changes in the SOC stock may result in large changes of atmospheric CO₂ particularly over tens to hundreds of years. In this study, we aim to (i) evaluate the SOC stock in the topsoil 0 - 15 cm from soil physical and chemical characteristics and (ii) find the correlation of SOC and soil organic matter (SOM) for national-scale in South Korea. First of all, based on the characteristics of the soil to calculate the soil hydraulic properties, SOC stock is the SOC mass per unit area for a given depth. It depends on bulk density (BD-g/cm³), SOC content (%), the depth of topsoil (cm), and gravel content (%). Due to insufficient data on BD observation, we establish a correlation between BD and SOC content, sand content, clay content parameter. Next, we present linear and non-linear regression models of BD and the interrelationship between SOC and SOM using a linear regression model and determine the conversion factor for them, comparing with Van Bemmelen 1890's factor value for the country scale. The results obtained, helps managers come up with suitable solutions to conserve land resources.