This study focused on improving the phase stability and mechanical properties of yttria-stabilized zirconia (YSZ), commonly utilized in gas turbine engine thermal barrier coatings, by incorporating Gd2O3, Er2O3, and TiO2. The addition of 3-valent rare earth elements to YSZ can reduce thermal conductivity and enhance phase stability while adding the 4-valent element TiO2 can improve phase stability and mechanical properties. Sintered specimens were prepared with hot-press equipment. Phase analysis was conducted with X-ray diffraction (XRD), and mechanical properties were assessed with Vickers hardness equipment. The research results revealed that, except for Z10YGE10T, most compositions predominantly exhibited the t-phase. Increasing the content of 3-valent rare earth oxides resulted in a decrease in the monoclinic phase and an increase in the tetragonal phase. In addition, the t(400) angle decreased while the t(004) angle increased. The addition of 10 mol% of 3-valent rare-earth oxides discarded the t-phase and led to the complete development of the c-phase. Adding 10 mol% TiO2 increased hardness than YSZ.

Yttria-stabilized zirconia (YSZ) has a low thermal conductivity, high thermal expansion coefficient, and excellent mechanical properties; thus, it is used as a thermal barrier coating material for gas turbines. However, during long-time exposure of YSZ to temperatures of 1200oC or higher, a phase transformation accompanied by a volume change occurs, causing the YSZ coating layer to peel off. To solve this problem, YSZ has been doped with trivalent and tetravalent oxides to obtain coating materials with low thermal conductivity and suppressed phase transformation of zirconia. In this study, YSZ is doped with trivalent oxides, Nd2O3, Yb2O3, Al2O3, and tetravalent oxide, TiO2, and the thermal conductivity of the obtained materials is analyzed according to the composition; furthermore, the relative density change, microstructure change, and m-phase formation behavior are analyzed during long-time heat treatment at high temperatures.

In this study, we measured the concentration of Particulate Matter (PM10), Formaldehyde (HCHO), and Total Bacteria Count (TBC) at three facilities: elderly care centers, day care centers, and postnatal care centers located in the cities of Seoul, Sejong, Daegu and Ulsan from January 1, 2012 to December 31, 2015. PM10 concentration was the highest in the day care centers and HCHO concentration was the highest in the postnatal care centers. TBC concentration was the highest in the day care centers. Comparing the different cities, PM10 concentration was the highest in Sejong, HCHO concentration was the highest in Seoul, and TBC concentration was the highest in Daegu. This study is expected to be helpful in preventing damage to health from the contaminated indoor air at sensitive facilities, and can be used as basic data for indoor air quality management.

An elementary school is a significant facility for educating and cultivating children and it is where they spend most of their days. The purpose of this study is to conduct an analysis on PM10 and TBC concentrations in 110 elementary schools in Suwon. We investigated 110 elementary schools from March 2011 to December in 2012. The mean concentration of PM10 and TBC were 51.3 ± 18.0 μg/m3(GM: 47.9 μg/m3) and 311.0 ± 125.3 CFU/m3 (GM:293.3 CFU/m3), respectively. All measurement concentrations did not exceed the Ministry of Education IAQ guidelines. Also, the concentrations of PM10 and TBC were not affected by various conditions such as Outdoor PM10, school construction year, class student number, temperature(oC) and humidity(%). The results of the study suggest that management of the IAQ plan in elementary schools should be implemented through Daily-Pattern and Activity-Pattern analysis for assessment of IAQ.

연변조선족자치주과학기술협회는 여러 분야의 과학협회 조직을 관리하는 정부의 직능을 가지고 있으며 대중의 과학 지식을 보급하는 군중단체조직입니다. 산하에 연변과학기 술관이 있습니다. 과학협회는 농업, 건강, 산업, 과학교육 등 대중화 지식을 전 연변에서 보급하는 활동을 진행하며 또 여러 협회를 통하여 장백산지역의 자원에 대한 조사, 연 구를 진행하며 대학교 기술자원과 인재자원을 이용하여 장 백산자원의 학술적인 연구를 하고있습니다. 직급은 과학기 술국과동등하며 국가과학기술협회주석은 중국에서 유명한 과학가만 될 수 있습니다.연변의 모든 발전은 장백산자원에 대한 탐구와 개발이 중요한 위치에 있는 만큼 앞으로의 사 업에서 더 큰 비중을 차지하고 있습니다. 근래에 장백산지 역의 인삼재배와 동식물에 대한 개발로 새로운 경제활성회 가 진행되고 있으며 깊은 관심을 가지고 있습니다. 신비한 장백산은 연변에서 새로 건설될 과학관의 전시에서도 주도 적인 위치로 자리 잡고 있습니다.

In this study, we attempted to estimate the association between asthma oriented by indoor air sources and personal exposure by comparing the case (asthma-patient) and control (non-asthma-patient) groups. We selected 27 participants who showed positive response on lung function and methacholin provocation test. We performed environmental survey with 15 and 10 cases during May and June 2007, respectively. There was no significant difference between the case and control groups in the level of formaldehyde and TBC (Total Bacterial Count). In the dust allergen test, the case concentration was higher than the control's, without signifiant difference. In the personal exposure assessment of VOCs using OVM (Organic Vapor Monitor) badge, the case concentrations of Benzene, Toluene, and Ethylbenzene were higher than the control's, but there was no significant difference. The personal exposure of Xylene case study was significantly higher than the control's

This study was followed up asthma incidence rate in primary schools indoor air quality. To investigate the history and prevalence rate of allergic diseases(asthma, atopy dermatitis, allergic rhinitis and conjunctivitis), the standardized and generally used International Study of Asthma and Allergies in Childhood(ISAAC) questionnaire was used to conduct the symptom survey for all participating subjects. The concentrations of major indoor air pollutants(dust mite allergen, aldehydes , VOCs, TBC, phthalate) were observed from April to May 2007. Sampling was undertaken at 19 primary schools. The sampling sites of air pollutants are classroom’s indoor and hallway. Dust mite allergen part it was detected from the case classroom and infirmary. The exposure quality of aldehyde and the place pollution level was indoor>outdoor>hallway, which whole is disease incidence rate high group appears more highly the low group than. The partially result of formaldehy and VOCs, the concentration of high environmental disease incidence rate showed also high. However, house dust allergen, TBC and phthalate measurement school was not the effect where the comparison of difference.

HIP처리가 가스터빈 고정익 등 고온부품에 적용되는 열차폐 코팅층의 접착강도 및 고온특성에 미치는 영향을 조사하였다. 시편은 IN738LC 초합금 표면에 8wt%Y2O3-ZrO2분말을 플라즈마 용사법으로 코팅한 후 1200˚C, 100MPa의 고온, 고압에서 4시간 동안 HIP 처리하여 준비하였다. 실험결과 HIP 처리된 코팅의 경우 미세균열과 기공이 상당량 감소하였으며 EDX분석을 통해 계면에서 원자간 상호확산이 발생한 것을 확인하였다. 이러한 코팅층의 치밀화 및 상호확산으로 인해 HIP처리된 코팅층의 접착강도는 48% 이상 크게 증가하였으며 조직 또한 균질화 되었다. 반면 가열과 냉각이 반복되는 환경에서 코팅층의 내구력은 HIP 처리된 경우가 다소 저하되었다. 이는 코팅과 모재와의 열팽창 차이로 인한 변형을 완화시켜주는 기공과 미세균열이 감소되었기 때문으로 판단된다.

플라즈마 용사법을이용하여 AISI 316 스테인레스 금속모재에 0.1mm 두께의 NiCrAlCoY2O3금속 결합층과 0.3mm 두께의 ZrO2(8wt%Y2O3) 세라믹층으로 구성된 이층 단열코팅층을 제조하였다. 코팅층의 미세조직, 금속결합층의 산화를 고찰하였으며, 900˚C에서 등은 시험과 열반복시험 후, 접합강도시험을 통하여 코팅층의 단사정 상은 열처리시간이 길어질수록 약간 증가하였다. 또한 비변태성 t'의 c/a는 용사상태에서 1.0099이였으며, 100시간 열처리 후에는 1.0115로 약간 증가하였다. 그리고 용사층의 접합강도는 열처리 시간이 길어질수록 감소하였다. 등온열처리 후에는 1.0115로 약간 증가하였다. 그리고 용사층 의 접합강도는 열처리 시간이 길어질수록 감소하였다. 등온열처리 후, 파괴는 주로 세라믹층에서 일어났으며, 반복 열처리되 시편에서는 10회 이후 대부분 금속결합층/세라믹층의 계면에서 일어났다.