• 토지주택연구
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• 제15권3호
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• pp.189-198
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• 2024

본 연구는 펄라이트와 EPS Beads를 활용한 단열 콘크리트의 열전도율과 구조적 특성을 분석하고, 물 흡수와 단열 성능 간의 상관관계를 규명하였다. 실험 결과, EPS Beads의 함유량이 4.2%일 때 가장 낮은 열전도율을 나타냈으며, 펄라이트의 함유량 증가에도 불구하고 열전도율의 변화가 나타나지 않았음을 확인하였다. 또한, 단열 콘크리트의 물 흡수를 최소화하는 것이 단열 성능 향상에 중요한 요소임을 발견하였으며, 이를 통해 도시의 탄소 중립 실현에 기여할 수 있음을 제시하였다. 이 연구는 지속 가능한 건축 재료 개발과 에너지 효율 향상에 기여할 수 있는 중요한 시사점을 제공한다.

• 한국세라믹학회지
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• 제44권12호
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• pp.747-750
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• 2007

The thermal conductivities of nano-sized fumed silica-based insulation media were investigated by varying a mean particle size of the silicon carbide opacifiers and ceramic fiber content. Opacifying effect of ceramic fiber and silicon carbide powders was discussed in terms of their content and the mean particle size of them. As the fiber contents increased from 10 wt% to 30 wt% in a material, its thermal conductivity at temperatures of about $620^{\circ}C$ decreased from 0.171 $Wm^{-1}K^{-1}$ to 0.121 $Wm^{-1}K^{-1}$. Meanwhile, the thermal conductivity at temperatures of about $625^{\circ}C$ decreased from 0.128 $Wm^{-1}K^{-1}$ to 0.092 $Wm^{-l}K^{-1}$ as the mean SiC particle size decreased from $31{\mu}m$ to $10{\mu}m$.

• 한국추진공학회지
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• 제27권1호
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• pp.9-16
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• 2023

본 연구에서는 고체추진기관 내 연소관단열재의 열분해와 삭마를 고려하여 단열재의 열응답을 예측할 수 있는 일차원 해석기법을 개발하였다. 모델링에는 연소관단열재 내부에서 발생하는 열분해로 인한 물성변화, 숯층의 팽창 및 분해가스 이동을 고려하였다. 또한 연소가스로부터의 복사/대류 열유속을 경계조건으로 적용하였으며 단열재 표면에서 발생하는 화학적 삭마속도를 대수식으로 모델링하였다. 해석기법 검증을 위해 열전대가 설치된 시험모터에 대한 해석을 수행하였다. 해석으로 도출된 온도분포는 시험과 유사한 값을 나타냈으며 시험과 예측 열파괴두께의 오차는 0.1 mm 내외였다.

• 유기물자원화
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• 제26권1호
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• pp.39-45
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• 2018

FA(Fly ash)에 대해서는 연구가 활발히 진행되는 반면 BA(Bottom ash)의 연구실적은 많지 않으며, 특히 BA 재활용 분야의 연구가 절실히 요구된다. 따라서 본 연구에서 다공성인 건식(공랭식) BA를 연구대상으로 선택해 이를 재료로 활용하여 만든 BA 모르터와 일반 모르터를 비교 분석하여 BA 모르터의 경량 및 단열 특성을 알아보고자 하였다. BA의 경량성을 알아보기 위해 밀도 시험, 단위용적질량 시험, SEM 시험을 하였으며, 단열 시험을 위해 BA 모르터와 일반 모르터 몰드를 KS A 0006에서 정한 상온 상습의 환경조건에서 제작 후 항량이 될 때까지 온도 $105{\pm}2^{\circ}C$에서 건조하였다. 경량성 시험 결과 BA 모르터의 경량성은 일반 모르터의 0.72배로 일반 모르터에 비해 약 30%정도 가볍게 측정되어 BA를 건축물 재료로 활용할 경우 건축물 하중을 줄이는데 크게 기여할 것이다. 또한 단열 시험 결과 BA 모르터의 열전도율은 일반 모르터의 0.70배로 약 30%정도 단열성이 우수하다.

• 한국태양에너지학회 논문집
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• 제37권4호
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• pp.35-47
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• 2017

Energy efficiency solutions are being pursued as a sustainable approach to reducing energy consumption and related gas emissions across various sectors of the economy. Vacuum Insulation Panel (VIP) is an energy efficient advanced insulation system that facilitates slim but high-performance insulation, based on a porous core material evacuated and encapsulated in a barrier envelope. Although VIP has been applied in buildings for over a decade, it wasn't until recently that efforts have been initiated to propose and adopt a global standard on characterization and testing of VIP. One of the issues regarding VIP is its durability and aging due to pressure and moisture dependent increase of the initial low thermal conductivity with time; more so in building applications. In this paper, the aging of commercially available VIP was investigated experimentally; thermal conductivity was tested in accordance with ISO 8302 standard (guarded hot box method) and long-term durability was estimated based on a non-linear pressure-humidity dependent equation based on study of IEA/ECBCS Annex 39, with the aim of assessing durability of VIP for use in buildings. The center-of-panel thermal conductivity after 25 years based on initial 90% fractile with a confidence level of 90 % for the thermal conductivity (${\lambda}90/90$) ranged from 0.00726-0.00814 (W/m K) for silica core VIP. Significant differences between manufacturer-provided data and measurements of thermal conductivity and internal pressure were observed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 전기설비
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• pp.23-24
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• 2006

Stator winding of hydro generator is gradually deteriorated by multi-stress and steady degradation of insulation results in insulation breakdown. The region where insulation breakdown occurs in stator winding is part where the multi-stress causes the defect of insulation material and electrical stress has been concentrated. Therefore, we judged locations of insulation breakdown to be varied according to various stress factors in service. In this paper, we drew the stator winding of hydro generators which has run for a long time and separated it into 3 parts(central part, end winding part, drawing part) according to the positions laid on the core. We performed electrical and thermal stress on these specimens for 1000 hrs under the same condition, measured the condition regularlyand analyzed the insulation status of each winding by performing partial discharge test. In addition, we analyzed the trend of partial discharge concerning specimens that caused the insulation breakdown during aging.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.88-88
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• 2010

High Voltage cross-linked polyethylene (XLPE) cables are widely used in a thermal power plant. These cables had been in service for 26 years. The insulation condition of six 6 kV XLPE cables was estimated by insulation diagnostic analyzer (IDA) with voltage amplifier. IDA was measured dissipation factor and capacitance of the whole cable as a function of frequency and voltage. This system measures in the frequency range from 0.1 to 10 Hz at each voltage level. Six XLPE cables are judged good condition, but three cables are analyzed at an aged condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.513-517
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• 1999

High voltage motor(rated 6.6kV and 448kw) has failed in the stator endwinding area during normal service. Experiments on microstructure property were conducted using the control and aged insulations, which were drawn out from stator windings of the high voltage motor. The analyses were characterized using stereozoom microscope(SM), scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy(EDS). SM result shows that large voids are present in the interface between turn insulation and groundwall insulation. SEM results indicated that the groundwall insulation is rarely thermal stress. EDS results showed that chemical elements in the high voltage motor stator insulations were Al, Si, O, K and Fe.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.93-101
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• 2002

In this study, the stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the C-Class(200$\^{C}$ ) insulation system of traction motors. The complex accelerative degradation was periodically performed during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, the condition diagnosis test such as insulation resistance '||'&'||' polarization index, capacitance '||'&'||' dielectric loss and partial discharge properties were investigated in the temperature range of 20 ∼ 160$\^{C}$. Relationship among condition diagnosis tests was analyzed to find a dominative degradation factor and an insulation state at end-life point.

• 한국의류학회지
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• 제16권3호
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• pp.251-256
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• 1992

As a basic expriment to find out the thermal insulation effect of bedding KES-F7 was used to measure. The warmth retaining ratio of the six kinds of filling materials as cotton, wool , silk, down, cotton/polyester was measured, and the infleunce on the warmth retaining ratio of the warmth retaining ratio and humidity by the material was investigated. The results obtained are as follows: 1. The warmth retaining ratio of each filling material was shown to range from $70\%$ to $77\%$ . The warmth retaining ratio of each material preyed to be high in order down> polyester> cotton/polyester>cotton>silk>wool fiber. 2. The warmth retaining ratio of each filling material decreased with the inclose of the humidity The effective reduction rate by filling fiber's was high in order wool>cotton>cotton/polyester>silk>down>polyester material. 3. The warmth retaining ratio of each filling material was shown to be in counter-correlation with the humidity, and the correlation coefficient (r=0.94-0.98) proved to be highly signi-ficant.