The development of thermoelectric (TE) materials to replace Bi2Te3 alloys is emerging as a hot issue with the potential for wider practical applications. In particular, layered Zintl-phase materials, which can appropriately control carrier and phonon transport behaviors, are being considered as promising candidates. However, limited data have been reported on the thermoelectric properties of metal-Sb materials that can be transformed into layered materials through the insertion of cations. In this study, we synthesized FeSb and MnSb, which are used as base materials for advanced thermoelectric materials. They were confirmed as single-phase materials by analyzing X-ray diffraction patterns. Based on electrical conductivity, the Seebeck coefficient, and thermal conductivity of both materials characterized as a function of temperature, the zT values of MnSb and FeSb were calculated to be 0.00119 and 0.00026, respectively. These properties provide a fundamental data for developing layered Zintl-phase materials with alkali/alkaline earth metal insertions.

Cement is widely used as representative industrial material. In Korea, about 50 million tons of cement are consumed every year. In the manufacture of cement, raw materials containing NORM such as fly ash and bauxite are used. Therefore, the workers can be subjected to radiation exposure. The major exposure pathway in NORM industries is internal exposure due to inhalation of aerosol. Internal radiation dose due to aerosol inhalation varies depending on physicochemical properties of the aerosol. Therefore, the objective of this study was to investigate aerosol properties influencing inhalation dose in cement industries. In this study, aerosol properties were measured for two cement manufacturers. A particulate size distribution and concentration at various processing areas in cement manufacturing industries in Korea were analyzed using a cascade impactor. The mass density of raw materials and byproducts were measured using pycnometer. Shape of particulates was analyzed using SEM. The radioactivity concentration of Ra-226, Ra-228 for U/Th decay series was measured using HPGe. Particulate concentration by size was distributed log-normally with maximum at particle size about 7.2 μm in manufacturer A and 5.2 μm in manufacturer B. The mass density of fly ash and cement were 2.3±0.06, 3.2±0.02 g/cm3 respectively in manufacturer A. In manufacturer B, the mass density of bauxite and cement were 3.4±0.02, 2.9±0.01 g/cm3 respectively. The shape of particulates appeared as spherical shape in manufacturer A and B regardless of sampling area. Thus, a shape factor of unity could be assumed. The radioactivity concentrations of Ra-226, Ra-228 were 82±9, 82±8 Bq/kg for fly ash, and 25±4, 23±3 Bq/kg for cement in manufacturer A. In manufacturer B, the radioactivity concentrations of Ra-226, Ra-228 were 344±34, 391±32 Bq/kg for bauxite, and 122±13, 145±12 Bq/kg for cement. The radioactivity concentrations of Ra-226, Ra-228 in cement were less than raw materials such as fly ash and bauxite. It is because the dilution of the radioactivity concentration occurred during mixing with other raw materials in cement production process. This study results will be used as database for accurate dose assessment due to airborne particulate inhalation by workers in cement industries.

본 연구에서는 폴리술폰 분리막을 이용한 바이오가스 정제 공정으로 고선택성 소재를 이용한 2단 공정의 높은 회 수율 및 경제성과 동등한 수준의 회수율을 확보하기 위해 저온 고압의 분리막 공정을 설계하고 평가하였다. 폴리술폰 고분자 를 4성분계 도프를 이용하여 비용매 유도 상전이법으로 중공사 분리막을 제조하였다. 기체 분리용 중공사 분리막은 1.6 m2의 유효 막면적을 갖는 샘플을 제조하여 상온 및 저온에서 기체 투과 특성을 평가하였다. 제조된 기체분리막 모듈의 온도에 따 른 기체 투과 특성을 분석하기 위하여 온도별 단일 기체 투과도를 평가한 결과 이산화탄소와 메탄 투과도는 20°C에서 각각 412, 12.7 GPU이며, -20°C에서는 각각 280, 3.6 GPU로써 이상 선택도는 32.4에서 77.8로 향상되었다. 단일 기체 투과 테스 트 후 혼합 기체에 대한 분리 테스트를 진행하였으며, 모듈 1단 구성 및 2단 구성(막 면적비 1:1, 1:2, 1:3)을 통하여 투과 거 동을 살펴보았다. 1단 구성에서는 stage-cut이 상승함에 따라 메탄의 농도가 상승하지만, 반대로 회수율은 떨어지는 결과를 나 타내었다. 2단 구성 테스트에서는 메탄 농도 97% 기준에서 막 면적비 1:1보다 1:3이 메탄의 회수율이 더 높게 측정되었으며, 공급 기체의 온도가 낮을수록 메탄의 회수율이 높아짐을 확인하였고, 최종적으로 폴리술폰 2단 공정에서 메탄 농도 97%, 회 수율 97%의 결과를 달성하였다.

The diaphragm is an important part because it plays an important role in changing the flow direction of hightemperature and high-pressure steam in the steam turbine. Because it is subjected to high pressure by high temperature steam, there should be great concerns about breakage of parts, runouts due to vibration by rotating parts, and deformation due to creep effect and fatigue breakage due to long-term use in high temperature environments. In order to ensure the safety of turbine components in such a harsh environment, structural analysis should be prioritized prior to manufacturing prototypes. In this study, in order to verify the design stability of the diaphragm, physical safety is checked through static analysis, vibration analysis, and fatigue analysis, and the fatigue life is predicted. The total deformation, equivalent stress, and strain are determined by static analysis, and the stress and total deformation by the harmonic response are obtained through vibration analysis, and the stability is judged by comparing it with the characteristic value. We intend to verify the safety of the design and propose a complementary diaphragm design.