In this study, we conducted the hot box tests to compare the changes in thermal insulation for the four types of multi-layer thermal screens by the used period after collecting them from the greenhouses in the field when they were replaced at the end of their usage. The main materials for these four types of multi-layer thermal screens were matt georgette, non-woven fabrics, polyethylene (PE) foam, chemical cotton, etc. These materials were differently combined for each multi-layer thermal screen. We built specimens (70×70 cm) for each of these multi-layer thermal screens and measured the temperature descending rate, heat transmission coefficient, and thermal resistance for each specimen through the hot box tests. With regard to the material combinations of multi-layer thermal screens, thermal insulation can be increased by applying a multi-layered PE foam. However, it is considered that the multilayered PE foam significantly less contributes to heat-retaining than chemical wool that forms an air-insulating layer inside multi-layer thermal screens. For the suitable heat-retaining performance of multi-layer thermal screens, basically, materials with the function of forming an air-insulating layer such as chemical cotton should be contained in multi-layer thermal screens. The temperature descending rate, heat transmission coefficient, and thermal resistance of multi-layer thermal screens were appropriately measured through the hot box tests designed in this study. However, in this study, we took into consideration only the four kinds of multi-layer thermal screens due to difficulties in collecting used multi-layer thermal screens. This is the results obtained with relatively few examples and it is the limit of this study. In the future, more cases should be investigated and supplemented through related research.

Abstract
 서 론
 재료 및 방법
  1. 다겹 보온자재의 시료채취
  2. Hot box 시험
  3. 시편별 Hot box 내부의 온도 하강률 비교방법
 결과 및 고찰
  1. Hot box 단열재의 관류열량 및 열관류율
  2. 시편별 Hot box 내부의 온도 하강률
  3. 시편별 열관류율 및 열전도저항 비교
 적 요
 Literature Cited

• 윤성욱(농촌진흥청 국립농업과학원 농업공학부) | Sung-Wook Yun (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA)
• 이시영(농촌진흥청 국립농업과학원 농업공학부) | Si-Young Lee (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA)
• 강동현(농촌진흥청 국립농업과학원 농업공학부) | Dong-Hyeon Kang (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA)
• 손진관(농촌진흥청 국립농업과학원 농업공학부) | Jinkwan Son (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA)
• 박민정(농촌진흥청 국립농업과학원 농업공학부) | Min-Jung Park (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA)
• 김희태(농촌진흥청 국립농업과학원 농업공학부) | Hee-Tae Kim (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA)
• 최덕규(농촌진흥청 국립농업과학원 농업공학부) | Duk-Kyu Choi (Dept. of Agricultural Engineering, National Institute of Agricultural Sciences, RDA) Corresponding author