Combustion of Medium Density Fibreboard (MDF) Specimens (Alkylenedi aminoalkyl-Bis-Phosphonic Acid Derivatives treatment)

Jisun You,Yeong-jin Chung 한국화재소방학회 2015 한국화재소방학회 학술대회 논문집 Vol.2015 No.추계

Combustion of Wood Specimens Treated with Alkylenediaminoalkyl -Bis-Phosphonic Acids

Jisun You,Yeong-jin Chung 한국화재소방학회 2015 한국화재소방학회 학술대회 논문집 Vol.2015 No.추계

Thickness-Dependent Fire Retardant Performance and Chemical Properties of Phenolic Foam

( Jisun You ),( Kyeongsin Kang ),( Minseo Lee ),( Minsoo Han ),( Sungyool Bong ) 한국공업화학회 2025 공업화학 Vol.36 No.1

In this study, we investigated phenolic foam (PF) materials with different thicknesses: 10T (PF-10), 30T (PF-30), and 50T (PF-50) based on phenolic foam with phosphorous, melamine cyanurate, trialkyl phosphate, and mono pentaerythritol. The PF materials undergo chemical conversion into carbonized materials during fire exposure. Our heat release rate (HRR) and smoke production rate (SPR) tests revealed that both PF-30 and PF-50 thickness-based PF materials effectively retard flame spreading due to the carbonization layer formed by combining phenol foam polymer and carbon nanotubes. From an economic standpoint, a phenolic foam board with a thickness of PF-30 is recommended. Although PF-50 exhibited slightly superior fire retardation properties, its greater thickness poses practical limitations in construction. Specifically, the material usage for PF-50 was approximately 1.7 times that of PF-30. Therefore, considering fire safety and cost-effectiveness, PF-30 emerges as the optimal choice for fire-retardant applications.

Chung's Equation-IX과 Chung's Equation-XII의 비교에 의한 목재 4종의 화재위험성 예측 및 화재위험성 등급 평가

유지선 ( Jisun You ),정영진 ( Yeong-jin Chung ) 한국공업화학회 2024 공업화학 Vol.35 No.3

Chung’s equations-IX and Chung’s equation-XII were utilized to predict the fire risk and evaluate fire risk ratings for four types of wood: camphor, cherry, rubber, and elm trees. The combustion tests were conducted using a cone calorimeter test method by ISO 5660-1 standards. The fire risk and fire risk rating (FRR) were compared for Fire Risk Index-IX (FRI-IX) and Fire Risk Index-XII (FRI-XII). The results yielded Fire Performance Index-XI (FPI-XI) ranging from 0.08 to 11.48 and Fire Growth Index-XI (FGI-XI) ranging from 0.67 to 111.89. The Fire Risk Index-XII (FRI-XII), indicating fire risk rating, exhibited an increasing order of cherry (0.45): Grade A (Ranking 5) < PMMA (1): Grade A (Ranking 4) < elm (1.23): Grade A (Ranking 3) < rubber (1.56): Grade A (Ranking 2) << camphor (148.23): Grade G (Ranking 1). Additionally, the fire risk index-IX (FRI-IX) was cherry (0): Grade A (Ranking 3) ≈ rubber (0): Grade A (Ranking 3) ≈ elm tree (0): Grade A (Ranking 3) < PMMA (1): Grade A (Ranking 2) << camphor tree (66.67): Grade G (Ranking 1). In general, camphor was found to have the highest fire risk. In conclusion, although the expression of the index is different as shown based on the standards of FRI-IX and FRI-XII, predictions based on fire risk assessment of combustible materials showed similar trends.

일부 목재와 플라스틱류의 연소 시 연기 위험성 등급 예측

유지선(JiSun You),정영진(Yeong-Jin Chung) 한국화재소방학회 2021 한국화재소방학회논문지 Vol.35 No.4

연구에서는 잣나무(pinus koraiensis, nut pine)와 갈참나무(quercus aliena, white oak) 그리고 폴리에틸렌(polyethylene,PE)과 폴리메타크릴산메틸(polymethyl methacrylate, PMMA)를 선정하여 ISO 5660-1의 기준에 따라 콘칼로리미터(conecalorimeter)를 이용하여 측정하였다. 측정된 값으로 Chung’s equations 1 (연기성능지수, SPI), Chung’s equations 2 (연기성장지수, SGI)에 의한 연기 위험성을 예측하고자 하였고, 이를 확장하여 화재 시 연기 위험성 평가를 표준화하기 위하여 기준물질(PMMA)을 사용하여 Chung s equations-V (연기성능지수-V, SPI-V와 연기성장지수-V, SGI-V)와 Chung sequation-VI (연기위험성지수-VI, SRI-VI)에 의한 연기 위험성을 등급화하여 평가하였다. SPI-V는 nut pine 0.73으로 가장낮았고, PE가 37.22로 가장 높았다. SGI-V에서도 PE가 0.03으로 가장 적게 나타나 연기가 가장 적게 발생하는 물질이고,nut pine이 10.00으로 가장 높게 나타나 다량의 연기가 발생하는 것으로 예측된다. SRI-VI는 PE (0.00) < PMMA (1.00)< white oak (1.44) << nut pine (13.70)의 순서로 나타났다. 따라서 PE의 연기 위험성이 가장 낮고, nut pine의 연기 위험성이 가장 높은 것으로 판단하였다. 또한 목재의 연소가 플라스틱류보다 불완전한 형태로 이루어짐을 알 수 있었다. In this study, pinus koraiensis (nut pine) and quercus aliena (white oak) and polyethylene (PE) and polymethylmethacrylate (PMMA) were selected. And it was measured with a cone calorimeter in accordance with ISO 5660-1. Withthe measured values, it was intended to comprehensively predict the risk of smoke by Chung’s equations 1 (smokeperformance index, SPI) and Chung’s equations 2 (smoke growth index, SGI). To standardize fire hazard assessment in caseof fire by extending this, standard materials (PMMA) were used to classify the smoke risk by the Chung s equations-V(smoke performance index-V, SPI-V and smoke growth index-V, SGI-V) and Chung s equation-VI (smoke risk index-VI,SRI-VI) to evaluate it. The SPI-V was the lowest with nut pine of 0.73 and the highest PE was the highest with 37.22. In the SGI-V, PE was the material that produced the least smoke with the least amount of 0.03. Nut pine is expected togenerate a large amount of smoke with the highest at 10.00. SRI-VI, it appeared in the order of PE (0.00) < PMMA (1.00)< white oak (1.44) << nut pine (13.70). Therefore, it was judged that PE had the lowest smoke risk and nut pine had thehighest. In addition, it was found that the combustion of wood was done in an incomplete form than that of plastics.

Daylight photodynamic therapy for actinic keratosis

( Jisun Yoon ),( You-chan Kim ) 대한피부과학회 2018 대한피부과학회 학술발표대회집 Vol.70 No.1

Photodynamic Therapy (PDT) is one of the standard treatment modalities for actinic keratoses (AKs). Daylight PDT (DL-PDT) with MAL cream, using daylight as light source, is one of recent treatment for AKs with less pain. Herein, we report a case of AK successfully treated with DL-PDT. A 71-year old Korean man presented erythematous scaly patches and was diagnosed AK by skin biopsy. The lesion was pretreated by fractional carbon dioxide laser first and then MAL cream was applied immediately. He went outdoors and exposed daylight for 2 hours. He reported little pain of visual analogue scale 1. Clinically cleared lesion was observed with 1 month and 2 month follow-up. No complication such as oozing or scar was reported.

A case of pediatric atypical spitz lesion

( Jisun Yoon ),( You Chan Kim ),( Jin Cheol Kim ),( Jee Woong Choi ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1

Term “Spitzoid tumor of uncertain malignant potential (STUMP)” has been used to describe lesions exhibiting features of benign Spitz nevi intermixed with malignant melanoma. Herein, we report a case of pediatric STUMP lesion. A 7-year-old girl presented an erythematous nodule on left arm appearing 6 months ago. The lesion was completely excised and the specimen demonstrated compound proliferation of enlarged spindle and epitheloid melanocytes with heavily pigmented cytoplasm. The lesion was diagnosed atypical Spitz nevus. Ultrasonography was performed to evaluate axillary lymph node and nodal abnormality was not observed. After 11 months, the lesion recurred and completely excised.

A Case of Pediatric Atypical Spitz Lesion

( Jisun Yoon ),( Jin Cheol Kim ),( You Chan Kim ),( Jee-woong Choi ) 대한피부과학회 2020 대한피부과학회지 Vol.58 No.1

Optimal Fluence and Duration of Low-Level Laser Therapy for Efficient Wound Healing in Mice

( Jisun Yoon ),( Ji Hyun Park ),( Jee-woong Choi ),( You Chan Kim ) 대한피부과학회 2021 Annals of Dermatology Vol.33 No.4

Background: Low-level laser (light) therapy is a promising technology that stimulates healing, relieves pain and inflammation, and restores function in injured body parts. However, few studies have compared the effects of lightemitting diodes of different fluence levels or different treatment durations. Objective: Here, we investigated the effects of various fluence levels and treatment durations on wound closure in mice. Methods: Full-thickness wounds were created on the dorsal skin using an 8-mm diameter punch, and the wounds were irradiated at 1, 4, or 40 J/cm² for 5 consecutive days starting on day 1. To determine the optimal irradiation duration, wounds were irradiated at the most potent fluence of previous study for 5, 10, or 15 days. Photographic documentation, skin biopsies, and wound measurements were performed to compare the effects of different treatment parameters. Results: The most effective fluence level was 40 J/cm² at day 5, as determined by monitoring wound closure. There were no statistically significant differences in wound healing with different durations. Conclusion: We have shown that repeated exposure to low levels of light significantly stimulates wound healing in mice and demonstrated more efficient wound closure with certain fluences of 830 nm irradiation. (Ann Dermatol 33(4) 318∼323, 2021)

Pozzolanic reaction of the waste glass sludge incorporating precipitation additives

You, Ilhwan,Choi, Jisun,Lange, David A.,Zi, Goangseup TECHNO-PRESS 2016 COMPUTERS AND CONCRETE Vol.17 No.2

The waste glass sludge is a waste produced in the glass industry. It is in a dust form and disposed with water. In the disposal process, various cohesive agents are incorporated in order to precipitate the glass particles efficiently. In this paper, we investigate the pozzolanic reaction of the waste glass sludge incorporating precipitation additives experimentally. The consumption of calcium hydroxide, the setting time and the compressive strength and the pore structure were tested for two different types of the waste glass sludge depending on whether precipitation additives were used. It was found that the waste glass sludge incorporating the precipitation additives had a higher pozzolanic potential than the reference waste glass sludge without precipitation additives.