The characteristics of aqueous lithium recovery by ion exchange were studied using three commercial cation exchange resins: CMP28 (porous type strong acid exchange resin), SCR-B (gel type strong acid exchange resin) and WK60L (porous type weak acid exchange resin). CMP28 was the most effective material for aqueous lithium recovery; its performance was even enhanced by modifying the cation with K+. A comparison to Na+ and H+ form resins demonstrated that the performance enhancement is reciprocally related to the electronegativity of the cation form. Further kinetic and equilibrium isotherm studies with the K+ form CMP28 showed that aqueous lithium recovery by ion exchange was well fitted with the pseudo-second-order rate equation and the Langmuir isotherm. The maximum ion exchange capacity of aqueous lithium recovery was found to be 14.28 mg/g and the optimal pH was in the region of 4-10.
This study was carried out to investigate the effect of deformation induced martensite on the damping capacity of Fe-26Mn-4Co-2Al damping alloy. α‘ and ε-martensite were formed by cold working, and; deformation induced martensite was formed with according to the specific direction and the surface relief. With an increasing degree of cold rolling, the volume fraction of α‘-martensite increased rapidly, while the volume fraction of ε-martensite decreased after rising to a maximum value at a specific level of cold rolling. Damping capacity was increased, and then decreased with an increasing of the degree of cold rolling. Damping capacity was influenced greatly by the volume fraction of ε-martensite formed by cold working, but the effect of the volume fraction of α‘-martensite have a actually on effect on the damping capacity.
Tungsten (W) thin film was deposited at 400 oC using pulsed chemical vapor deposition (pulsed CVD); film was then evaluated as a nucleation layer for W-plug deposition at the contact, with an ultrahigh aspect ratio of about 14~15 (top opening diameter: 240~250 nm, bottom diameter: 98~100 nm) for dynamic random access memory. The deposition stage of pulsed CVD has four steps resulting in one deposition cycle: (1) Reaction of WF6 with SiH4. (2) Inert gas purge. (3) SiH4 exposure without WF6 supply. (4) Inert gas purge while conventional CVD consists of the continuous reaction of WF6 and SiH4. The pulsed CVD-W film showed better conformality at contacts compared to that of conventional CVD-W nucleation layer. It was found that resistivities of films deposited by pulsed CVD were closely related with the phases formed and with the microstructure, as characterized by the grain size. A lower contact resistance was obtained by using pulsed CVD-W film as a nucleation layer compared to that of the conventional CVD-W nucleation layer, even though the former has a higher resistivity (~100 μΩ-cm) than that of the latter (~25 μΩ-cm). The plan-view scanning electron microscopy images after focused ion beam milling showed that the lower contact resistance of the pulsed CVD-W based W-plug fill scheme was mainly due to its better plug filling capability.
An amide group was introduced to restrain the cohesion of silica nano-particles and copolymerized with polyamic acid. Amide block copolymers were prepared using silica and (3-mercaptopropyl) trimethoxysilane (MPTMS) with a siloxane group, using 2, 6-Lutidine as a catalyst. Amide block polymers and copolymers were synthesized via ATRP after brominating pyromellitic dianhydride (PMDA) and polyamic acid of methylene diphenyl diamine (MDA) using α-bromo isobutyryl bromide. Characteristic peaks of copolymer with amide and imide groups and patterns of amorphous polymers were studied using FT-IR and XRD analyses; an analysis of the surface characteristic groups was conducted via XPS. Changes in the thermal properties were examined through DSC and TGA; solubility for solvents was also studied.
Microstructure evolutions of thermosetting resin coating layers fabricated by electrostatic spray deposition (ESD) at various processing conditions were investigated. Two different typical polymer systems, a thermosetting phenol-formaldehyde resin and a thermoplastic polyvinylpyrrolidone (PVP), were employed for a comparative study. Precursor solutions of the phenol-formaldehyde resin and of the PVP were electro-sprayed on heated silicon substrates. Fundamental differences in the thermomechanical properties of the polymers resulted in distinct ways of microstructure evolution of the electro-sprayed polymer films. For the thermosetting polymer, phenol-formaldehyde resin, vertically aligned micro-rod structures developed when it was deposited by ESD under controlled processing conditions. Through extensive microstructure and thermal analyses, it was found that the vertically aligned micro-rod structures of phenol-formaldehyde resin were formed as a result of the rheological behavior of the thermosetting phenol-formaldehyde resin and the preferential landing phenomenon of the ESD method.
SnO2:CNT thick films for gas sensors were fabricated by screen printing method on alumina substrates and were annealed at 300 oC in air. The nano SnO2 powders were prepared by solution reduction method using tin chloride (SnCl2.2H2O), hydrazine (N2H4) and NaOH. Nano SnO2:CNT sensing materials were prepared by ball-milling for 24h. The weight range of CNT addition on the SnO2 surface was from 0 to 10 %. The structural and morphological properties of these sensing material were investigated using X-ray diffraction and scanning electron microscopy and transmission electron microscope. The structural properties of the SnO2:CNT sensing materials showed a tetragonal phase with (110), (101), and (211) dominant orientations. No XRD peaks corresponding to CNT were observed in the SnO2:CNT powders. The particle size of the SnO2:CNT sensing materials was about 5~10 nm. The sensing characteristics of the SnO2:CNT thick films for 5 ppm H2S gas were investigated by comparing the electrical resistance in air with that in the target gases of each sensor in a test box. The results showed that the maximum sensitivity of the SnO2:CNT gas sensors at room temperature was observed when the CNT concentration was 8wt%.
Activated carbons (ACs) have been used as EDLC (electric double-layer capacitor) electrode materials due to their high specific area, stability, and ecological advantages. In order to prepare ACs with high density and crystallinity, coal tar pitch (CTP) was activated by K2CO3 and the textural and electrochemical properties of the obtained ACs were investigated. Although the CTP ACs formed by K2CO3 activation had much smaller specific surface area and pore volume than did the CTP ACs formed by KOH activation, their volumetric specific capacitance (F/cc) levels as electrode materials for EDLC were comparable due to their higher density and micro-crystallinity. Structural characterization and EDLC-electrode performance were studied with different activation conditions of CTP/K2CO3 ratio, activation temperature, and activation period.
The deposition process for the gap-filling of sub-micrometer trenches using DMDMOS, (CH3)2Si(OCH3)2, and CxHyOz by flowable chemical vapor deposition (F-CVD) is presented. We obtained low-k films that possess superior gap-filling properties on trench patterns without voids or delamination. The newly developed technique for the gap-filling of submicrometer features will have a great impact on IMD and STI for the next generation of microelectronic devices. Moreover, this bottom up gap-fill mode is expected to be universal in other chemical vapor deposition systems.
We measured VOCs and NO2 in the indoor and outdoor air at 125 houses in Jeollanam-do and Gyeongsangnamdo, from March 2007 to January 2008. The concentration of benzene measured in the Gwangyang survey group was higher than in Yeosu and Hadong, and showed a statistically significant difference from Yeosu (p<0.05). The concentration of toluene in outdoor air was highest in the Gwangyang survey group. The concentration of NO2 measured in the Yeosu survey group was higher than in Gwangyang and Hadong, and showed a statistically significant difference from Hadong (p<0.01). According to the results of a correlation analysis, VOCs (benzene, toluene, xylene, ethylbenzene) exposure of individuals showed a significant correlation with the residential indoor air (p<0.01). Also, VOCs of residential indoor and outdoor air showed a significant correlation (p<0.01). The concentration of NO2 exposure of individuals measured in the Yeosu comparison group showed a high correlation with the residential indoor air.
About half of the South Korean population lives in the three major metropolitan areas, which are Seoul, Kyeonggi and Incheon. Among this group, more than 50% live in apartments. In this study, the relationship between the concentration of indoor VOCs and environmental factors was investigated in metropolitan apartments in the occupation stage. The maximum concentration of TVOC (total volatile organic compounds) was monitored in spring season. Among the identified VOCs, toluene was present in the highest amount, followed by terpene, aldehyde and hydrocarbon. Due to the specific indoor sources, the I/O ratio of terpene (e.g. d-limonene, α-pinene, and β-pinene) was relatively higher than that of the others. The construction year and length of residence were revealed as the environmental factors having the greatest influence on the concentration of indoor benzene, toluene, ethylbenzene, xylene, styrene and hydrocarbon, and the relationship was statistically significant. The floor and size of the apartment influenced the levels of indoor nonanal. The relationships between individual VOCs showed highly positive correlations that are statistically significant. Through the relationship study, it was found that factors including newly built apartment, short period of time after moving in, high floors and small floor area were the main factors inducing an increased concentration of indoor VOCs in apartments.
The objective of this study was to assess RF-EMF exposure levels in indoor daycare centers in a Metropolitan city. RF-EMF measurements were collected and surveyed from 50 volunteer daycare centers in the Korea between October 2013 and October 2014. Through our research, it was found that the main exposure source for indoor daycare centers is the frequency bands for TV and Radio broadcasting (FM: 88.1~107.9 MHz), mobile phone (869~894 MHz, 1840~1870 MHz, 1885~2170 MHz), wireless LAN and home electronics, etc., including TRS, Wireless Data Communication. The RF-EMF exposure levels for all daycare centers were far below the recommended standards of EMF Guideline Korea and international reference levels proposed by ICNIRP (International Commission on Non-Ionizing Radiation Protection). However, in terms of long term health effects some uncertainty exists, and thus minimizing exposure may reduce this uncertainty. The data we collected will be useful data for determining RF-EMF management and risk communication at daycare centers.
In the current study, oxidative decomposition of a volatile organic compound was investigated at room temperature and pressure. The experiment was carried out in lower ethylene concentration and with various higher gas flow rates. The reactor has 7 different compartments in which the reaction takes place independently. Plasma was generated inside each compartment by the application of alternating current (AC) voltage. 5 wt% manganese loaded and 5 wt% silver loaded 13X zeolite were used as catalysts. Bare zeolite showed higher ethylene decomposition efficiency than Ag loaded and Mn loaded zeolite. Ozone concentration was increased slightly while increasing the SIE, reached a maximum and started decreasing. Ag loaded zeolite also showed similar decomposition efficiency, but the concentration of ozone was greatly lowered.
Hydrogen sulfide (H2S) emitted from various sources is a major odorous compound, and non-thermal plasma (NP) has emerged as a promising technique to eliminate H2S. This study was conducted to investigate lab-scale and pilot-scale NP reactors using corona discharge for the removal of H2S, and the effects of relative humidity, applied electrical power on reactor performance and ozone generation were determined. A gas stream containing H2S was injected to the lab-scale NP reactor, and the changes in H2S and ozone concentration were monitored. In the pilotscale NP experiment, the inlet concentration and flow rate were modified to determine the effect of relative humidity and applied power on the NP performance. In the lab-scale NP experiments, H2S removal was found to be the 1st-order reaction in the presence of ozone. On the other hand, when plasma reaction and ozone generation were initiated after H2S was introduced, the H2S oxidation followed the 0th-order kinetics. The ratio of indirect oxidation by ozone to the overall H2S removal was evaluated using two different experimental findings, indicating that approximately 70% of the overall H2S elimination was accounted for by the indirect oxidation. The pilotscale NP experiments showed that H2S introduced to the reactor was completely removed at low flow rates, and approximately 90% of H2S was eliminated at the gas flow rate of 15 m3/min. Furthermore, the elimination capacity of the pilot-scale NP was 3.4 g/m3·min for the removal of H2S at various inlet concentrations. Finally, the experimental results obtained from both the lab-scale and the pilot-scale reactor operations indicated that the H2S mass removal was proportional to the applied electrical power, and average H2S masses removed per unit electrical power were calculated to be 358 and 348 mg-H2S/kW in the lab-scale and the pilot-scale reactors, respectively. To optimize energy efficiency and prevent the generation of excessive ozone, an appropriate operating time of the NP reactor must be determined.
The indoor air quality of residences has been regulated by designating recommended standard levels of pollutants for newly built apartments. But as of yet, no related guideline has been established for dwellings that are already occupied. From a sociological viewpoint, the gap between the rich and poor has been gradually increasing with economic development, and this has extended to the diversification of house types and living environments. Specifically, people who have the lowest income levels may live in temporary houses such as vinyl greenhouses and shanty houses, and their living environment is mostly inadequate as a result. In this study, we surveyed the indoor air quality in normal and socially vulnerable houses after the occupation stage and tried to figure out the main factors influencing indoor air quality. Airborne fungi are detected more frequently in lower living standard houses. Put another way, the concentration of airborne bacteria and the volatile organic compound levels are much higher than in normal dwellings.
이글은 최근까지 세계적으로 주목 받고 있는 타이완의 영화감독 허우샤오시엔의 영화에 대한 새로운 해석이다. 그중에서도 1989년 작품 《비정성시(悲情城市:A City of Sadness : 1989)》 를 재조명하는 것이다. 그리고 지금의 시점에서 그의 영화를 다시 보면서 작품 속에서 그의 영화 가 갖고 있는 특성과 그 영화들이 가지는 시대적 배경의 모습, 그러한 것들과 인간적 환경에 대 하여 주목한다. 이는 그가 말했듯이 영화를 만드는 일은 결국 역사와 사람을 알아가는 과정일 것이다. 그는 인간의 삶이 의지적인 것과 결코 의지적이지 않은 반대의 면이 있다는 것을 표현하 고자 했다. 특히 인간이 가지는 원초적 진실함이 어떻게 넓은 중국 속에서, 타이완이라는 중국의 한 부분 지역에서, 그리고도 극히 일부분에 불과한 지역에서 겪는 상황에 대해서, 그리고 시대의 변화가 많은 변곡점과 마주치면서 겪는 인간의 한계를 영화의 매개체를 통하여 특히, 그가 만든 스크린을 통하여 어떻게 비추어내는가 하는 것을 보여주고 있다. 그의 영화가 유명하거나 많은 상을 받아서가 아니라 그가 감독하였거나 제작한 영화들은 시대가 바뀌어도 항상 재조명되고 관 객들로 하여금 다시 감상되어야 할 필요가 크므로 우리는 그의 작품에 대해서 특히 그의 8년만의 역작이며, 아름답지만 슬픈 《悲情城市》를 다른 작품과 더불어 재조명 하고자 한다.
The purpose of this study is to produce the auxiliary fuel additives that will improve the heat value and reduce the odor of dried sewage sludge, an auxiliary fuel for power plants using process by-products. Through an odor analysis prior to the production of auxiliary fuel additives, it was confirmed that the main odor materials are Methylmercaptan, Acetaldehyde and Trimethylamine. Based on this, we measured the heating value on various processes by-products such as by-products of thermal power generation and by-products of refinery. In addition, the adsorption performance in the major odor material was evaluated. However, for Trimethylamine, it is very difficult to secure the reproducibility of the concentration of the standard materials as the standard material is liquid. Therefore, it was used Ammonia, which has basic property, to replace Trimethyamine. In the evaluation of various process by-products, the highest heating value in heavy oil fly ash was 5,575 kcal/kg, while in the adsorption performance evaluation, FCC was shown as having the best performance in adsorption, as it could adsorb 100% of Methylmercaptan, 47% of Acetaldehyde and 76% of Ammonia. We conducted an adsorption experiment after supporting a transition metal on the FCC in order to improve the adsorption capacity. As a result, it was confirmed the best efficiency when supporting the copper nitrate 0.5% on the FCC. Based on this result, the experiment was conducted to determine the optimal mixing ratio with a high heating value and odor reducing function using Heavy oil fly ash and FCC. The optimal mixing ratio was 90% of Heavy oil fly ash and 10% of FCC. Furthermore, it was found that the most economical performance and highest odor reducing efficiency was achieved when the mixing ratio was 90% of dried sewage sludge and 10% of auxiliary fuel additives.
The study analyzed performance assessment factors of VOCs odor sensors from 3 different manufacturers, such as minimum detection limit, humidity stability and temperature stability. Through the minimum detection limit assessment, it was found that a VOCs sensor was able to detect TVOCs at the concentration of 5 ppb. The standard deviation ratio was over 10%, and it increased as humidity rose. The range of temperatures in which the VOCs odor sensor using photoionization could operate was between 25oC and 40oC, and the sensor output values were unstable at low temperatures. In terms of the temperature stability of the metal oxide semiconductor sensor for measuring complex odors, the sensor output values dropped considerably to 0~10oC, and were similar to the concentrations of odorous gases generated at 25oC. The results of the test of VOCs odor sensor outputs after temperature and humidity pre-treatment revealed that the respective stable output values at 50% humidity and 25oC were similar to the concentrations of manufactured odors. In terms of temperature and humidity stability of the VOCs odor sensors, all target VOCs substances had stable output values at 25oC to 40oC and at 50% to 65% relative humidities, and unstable values at low temperatures and high humidities. Therefore, the implementation of pre-treatment systems including temperature and humidity correction (25~40oC, 50~65% RH) is required for the stable use of VOCs odor sensors.
Radon (222Rn) gas is a main source of ionizing radiation of natural origin. It typically moves up through the ground to the air above and into building or home through cracks and other holes in the foundation. Significantly, the Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today. This survey covers the determination of indoor radon concentrations at home from 2013 to 2014 in some areas of Gangwondo, every three months (seasonal) during one year using an alpha-track detector. The results showed that the annual average concentration of indoor radon was 84.5 Bq/m3 (GM: 64.5 Bq/m3) at homes. Indoor radon level was the highest in winter and the lowest in summer. Geometric mean radon concentration in winter was 1.03~2.58 times higher than other seasons. The data obtained from this study provide a basis for the preparation of legal regulation and public health protection manuals in this area.
This study was an attempt to analyze the basic analytical characteristics of octanal and nonanal compounds by TD and GC/FID system. The basic analysis (linearity, precision, MDL: method detection limit) showed similar results for VOCs in terms of QA/QC results with the same analysis system. Also, the results are sufficiently satisfy the QA/QC of the Korean odor analysis standard method. When using a polyester aluminum bag, the amount of loss was found to be about -2% to 7%. Adjusting the relative humidity and loss trend with the passage of time, the loss amount is found to be only a trace amount. With the exception of the styrene compound, all volatile organic compounds have a tendency to decrease slightly. Similar results were shown from Octanal and Nonanal. As a result, Octanal and Nonanal compound’s adsorption amount by the polyester aluminum bag was a quite small. The relative humidity and other compounds appear to be significantly unaffected by Octanal and Nonanal.
이 연구는 TV 드라마 <시그널>의 주요 모티브인 과거, 현재, 미래가 상호작용하는 서사적 시 간 구성이 극적 긴장을 조성하는 데 어떤 역할을 했는지를 분석한다. 분석을 위한 이론적, 방법 론적 도구로 페터 퓌츠(Peter Pütz, 1977)가 제시한 서사물에서의 극적 긴장 조성 기법들을 활 용한다. 그리고 서사적 시간성에 대한 오랜 이론적 토대를 제공해온 쥬네트와 채트먼의 논의를 퓌츠와 비교한다. 이 글의 목적은 TV 드라마 <시그널>의 서사형식을 밝히는 것이다. 특히 서사 적 시간성을 뒤흔들어서 극적 긴장감을 불러일으키는 서사적 변형을 살펴보는 것이다. 이는 <시 그널>의 시간성과 시간을 통한 극적 긴장의 조성 기법이 <시그널>의 극적 완성도를 높이기 위해 서 어떻게 활용됐는가를 분석하는 것이다. 이를 통해서 서사적 시간성 문제에 대한 이론적 지평 을 확장하는 것이 이 연구의 궁극적 목표라고 할 수 있다. 페터 퓌츠가 제시한 극적 긴장을 조성 하는 기법들인 서사적 시간 구성의 다양한 요소들이 <시그널>의 전편에서 복합적으로 활용되고 있었다. ‘연속’과 ‘선취’, ‘역전’이라는 긴장 조성의 기법들은 <시그널>의 과거와 현재 혹은 현재 와 미래라는 이중적 서사 속에 자연스럽게 녹아들고 있었다. 이러한 극적 긴장 조성의 기법들은 <시그널>의 모티브인 무전기를 통해서 과거와 현재가 만난다는 서사적 설정에 매우 적합한 재현 도구로 쓰였다. <시그널>은 극적 긴장을 조성하는 기법들을 통해서 서사와 시간을 복합적이면서 도 체계적으로 구조화하는 데 성공했다. 즉 <시그널>의 대중적 성공과 높은 작품성은 서사적 시 간의 구조화와 그에 따른 극적 긴장의 성공적 조성에서 기인한다고 하겠다. 아울러 주요 캐릭터 역시 그러한 시간적 구조화에서 극적 긴장 조성의 기법적 역할을 수행했다. 이는 캐릭터 연구에 있어서도 중요한 관심의 대상이 될 수 있을 것으로 보인다. 끝으로 최근 늘고 있는 독특한 시간 성 혹은 멀티타임의 시간성을 모티브로 하여 제작되는 영화나 TV 드라마에 대한 연구와 분석에 있어서 극적 긴장을 조성하기 위한 방법을 제안한 퓌츠의 논의는 더욱 더 유용할 것으로 판단된 다.