석면 함유 천장재에 대한 석면 안정화제 내구성 평가 연구

하주연 ( Joo-yeon Ha ),신현규 ( Hyun-gyoo Shin ) 한국산업보건학회 (구 한국산업위생학회) 2020 한국산업보건학회지 Vol.30 No.1

Objectives: For testing asbestos stabilizer products which are used for the maintenance and management of asbestos-containing materials, durability assessment should accompany the evaluation of basic properties and performance. Therefore, in this study we designed a testing method and constructed a database of durability performance, thereby providing basic data for reliability studies of asbestos stabilizer. Methods: Since the ceiling materials targeted in this study are interior materials, test conditions of 95% relative humidity and 60℃ temperature were designed in consideration of the effect of high relative humidity in summer and seasonal indoor temperatures. Plate-shaped specimens treated with asbestos stabilizers were maintained in a thermo-hygrostat for 5, 10, and 20 days, and then the asbestos scattering prevention rate was measured by air erosion testing. Results: The scattering concentration tended to increase with time under the single humidity condition, and exceeded the indoor air quality standard of 0.01 f/cc, during the 20 days of maintenance. On the other hand, there was little change according to the temperature condition. In the case of a complex condition with temperature and humidity, the results were similar to the humidity test, but the scattering concentration increased more sharply at 20 days. Conclusions: The main deterioration factor that affects the durability of asbestos stabilizer is humidity, and the deterioration is caused by a mechanism in which the stabilizer coated on the surface is re-dissolved by moisture and evaporates or the coating layer is peeled off, which is accelerated by high temperatures.

MLCC용 x(Na0.5K0.5)NbO3-(1-x)BaTiO3 세라믹스의 미세구조 및 구조 분석

하주연 ( Joo Yeon Ha ),김진성 ( Jin Seong Kim ),이희수 ( Hee Soo Lee ),최연규 ( Youn Kyu Choi ),이연숙 ( Yeon Sook Lee ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.5

The doping effect of (Na0.5K0.5)NbO3(NKN) on the crystal structure, microstructure and electrical properties of BaTiO3 (BT) ceramics was investigated as alternatives for rare-earth elements. x(Na0.5K0.5) NbO3-(1-x)BaTiO3 ceramics with 0.00 ≤ x ≤ 0.10 were synthesized by a solid-state reaction method. The dielectric constant and the insulation resistance (IR) of the sample with x=0.05 were about 43% and 45% higher, respectively, than those of the undoped one, and the temperature coefficient of capacitance (TCC) met the X7R specification. The sample with x=0.05 had the lowest tetragonality among the four compositionsand had the finest grain size of < 2 um. The sample doped over the solubility limit (x=0.10) showed the lowest dielectric properties by the presence of a secondary phase with a needle shape. Although the addition of NKN decreased the tetragonality, the electrical properties were enhanced by the formation of the defect dipole and conduction electron, which are caused by the compensation of oxygen vacancy and electron. The addition of x=0.05 NKN to BaTiO3 improved the electrical properties due to the substitution behavior that resulted in making the defect dipole and conduction electron.

건설 해체 현장 내 석면 안정화제 적용 기술 소개

하주연,신현규,Ha, Joo-Yeon,Shin, Hyun-Gyoo 한국건설순환자원학회 2020 한국건설순환자원학회지 Vol.15 No.2

BCAR3 Activates the Estrogen Response Element through the PI3-kinase/Akt Pathway in Human Breast MCF-12A Cells

Myung-Ju Oh(오명주),Joo-Yeon Ha(하주연),Byung H. Jhun(전병학) 한국생명과학회 2022 생명과학회지 Vol.32 No.11

Breast cancer anti-estrogen resistance 3 (BCAR3)는 유방암에서 항에스트로겐 내성을 유도하는 유전자들 중의 하나로 발견되었다. 우리는 이미 BCAR3가 c-jun, activator protein-1, serum response element의 promoter 등을 활성화하는 것을 보고하였다. 본 연구에서 우리는 정상 유방세포인 MCF-12A에서 estrogen response element (ERE) 활성에서의 BCAR3의 기능을 조사하였다. BCAR3의 발현이 ERE를 활성화하는 것을 발견하였다. 이 ERE 활성화는 17β-estradiol에 의해 더욱 증가하였고, 이는 항에스트론겐인 tamoxifen에 의해 억제되지 않았다. 다음으로 우리는 ERE 활성화를 이끄는 BCAR3의 신호전달 경로를 연구하였다. BCAR3에 의한 ERE 활성화는 phosphatidylinositol (PI) 3-kinase 경로 억제제인 LY294002와 AZD5363에 의해서는 억제되었으나, Mitogen-activated protein kinase 경로 억제제인 PD98059와 U0126에 의해서는 억제되지 않았다. ERE 활성화는 PI3-kinase의 catalytic subunit p110α와 Akt의 active mutant에 의해서는 유도되었고, 이 활성화는 추가적인 BCAR3에 의해서는 더욱 증가하지 않았다. 이러한 결과로부터 우리는 BCAR3가 PI3-kinase/Akt 신호전달경로를 통하여 ERE 활성화에 중요한 역할을 하는 것을 제시한다. Breast cancer anti-estrogen resistance 3 (BCAR3) has been identified as one of the genes that induces anti-estrogen resistance in breast cancer. We have previously reported that BCAR3 activates promoters of c-Jun, activator protein-1, and the serum response element. In this study, we investigated the functional role of BCAR3 in the activation of the estrogen response element (ERE) in normal human breast MCF-12A cells. Transient expression of BCAR3 induced ERE activation, which was further increased by 17β-estradiol treatment but was not blocked by the anti-estrogen tamoxifen. Next, we studied the signaling pathway of BCAR3 leading to ERE activation. BCAR3-mediated ERE activation was inhibited by LY294002 and AZD5363, inhibitors of the phosphatidylinositol (PI) 3-kinase pathway, but not by PD98059 and U0126, inhibitors of the mitogen-activated protein kinase pathway. ERE activation was induced by the catalytic subunit p110α of PI3-kinase or the active mutant of Akt, and this activation was not further increased by additional BCAR3 transfection. Based on these results, we propose that BCAR3 plays an important role in ERE activation through the PI3-kinase/Akt pathway in human breast MCF-12A cells.

재활용 석고 부산물을 이용한 유무기 하이브리드 흡음재 개발 연구

신현규(Hyun-Gyoo Shin),전보람(Bo-Ram Jeon),하주연(Joo-Yeon Ha),전찬수(Chan-Soo Jeon) 한국건설순환자원학회 2017 한국건설순환자원학회 논문집 Vol.5 No.4

본 연구에서는 유기계 소재의 폴리우레탄 스펀지를 무기계 바인더 용액에 함침시킴으로써 유무기 하이브리드 구조의 흡음재를 개발하였다. 무기계 바인더 용액은 α형 반수석고에 60%의 물과 경화 지연제, 유동화제, 아크릴 수지 등의 혼화 재료를 첨가하여 슬러리 용액으로 제조하였으며, 무기계 바인더 용액에 함침시킨 유기계 스펀지를 함침, 가압탈수, 건조시킴으로서 특성평가용 시료를 제작하였다. 개발 시료의 흡음률을 임피던스 관내법을 이용하여 시험 평가한 결과, NRC 흡음계수 값은 0.41로 기존에 시판되고 있는 흡음재들과 비교하여 2배 이상으로 우수한 흡음성능을 나타냈으며, 불연성능 시험평가 결과 준불연재료(2급) 기준을 만족함을 확인하였다. 또한 건축 내장재로서의 기초 시험평가 및 EL248. 규격에 따른 유해성분 시험평가를 통해 본 연구에서 개발한 유무기 하이브리드 소재가 흡음재뿐만 아니라 단열 및 보온재로서의 역할이 가능하며, 유해성 기준을 만족하는 친환경 건축소재로 활용 가능함을 확인하였다. The purpose of this study is to develop the hybrid sound-absorbing materials that is made from organic polyurethane sponge impregnated with inorganic binder solutions. The inorganic slurry which is made from α-hemihydrate gypsum mixed with 60% water, and various additives including plasticizer are used as binder. The test specimens are prepared and tested for sound absorption performance by the impedance tube methods. From the test results, noise reduction coefficient(NRC) of development materials specimen bound by the inorganic binder slurry is 0.41. They are 2 times or more higher than commercial products specimens bound by organic materials only which have NRC values in the range of 0.14 to 0.28. The polyurethane sponge specimens impregnated with inorganic gypsum slurry binder have a good balance between performance and cost, and have proper properties in density, thermal conductivity, non-combustible, and absence of harmful substances as sound-absorbing internal boards for noise barrier wall. It is apparent that the good sound absorption materials can be produced according to the optimum mix design that is recommended from this study.

석면 함유 천장재의 안정화제 희석에 따른 침투깊이 연구

신현규 ( Hyung Yoo Shin ),최용규 ( Young Kue Choi ),전보람 ( Bo Ram Jeon ),하주연 ( Joo Yeon Ha ) 한국산업보건학회 2015 한국산업보건학회지 Vol.25 No.1

Objectives: This study is designed to analyze the penetration performance into ceiling materials containing asbestos of scattering prevention agents and investigate the change in penetration depth and viscosity according to the dilution rate of anti-scattering agents diluted with distilled water. Methods: Five different types of scattering prevention agents were spread on plate-type asbestos ceiling materials. The penetration depth of each coated ceiling material was measured by energy dispersive spectroscopy (EDS) analysis, based on X-ray fluorescence (XRF) results of the non-coated ceiling materials. Test equipment installed the ceiling materials and 60 minutes were collected at a flow rate of 10 ℓ/min at a filter of 25 mm. Results: An EDS analysis of the cross-section of ceiling materials constructed with a scattering prevention agent revealed that potassium is detected in the process of penetrating hardener solidification and this element could be an indicator for infiltration. When anti-scattering agents with different viscosities were constructed and the penetration depth was analyzed by potassium detection assessment using EDS, the depth results with viscosities of 5.0, 2.5, and 1.9 cP were 98.5, 103, and 147 μm, respectively. Penetration performance improved with decrease in viscosity. Conclusions: For asbestos ceiling materials, it is concluded that a higher dilution rate of the scattering prevention agent leads to lower viscosity, and hence a deeper penetration depth from 156 ㎛to 3 mm. The asbestos anti-scattering properties according to the penetration depth will be confirmed through further study.