The purpose of this study was to investigate the odor arising from the Cheong-ju industrial complex area for odor materials confirmation, and to predict the impact of the odor in the residential area using the CALPUFF Model. Among the odor causing substances in the area with a rising number of collective complaints due to odor, methyl sulfide, acetaldehyde, propionaldehyde, n-buthylaldehyde, n-valeraldehyde and styrene were detected. Odor causing substances detected in the area surrounding the industrial complex include ammonia, hydrogen sulfide, n-buthylaldehyde, toluene, xylene, benzene and styrene. Using the CALPUFF Model, it was predicted that 1hr average was 3.981~7.553 OU/m3 and 24hr average was 1.753~2.359 OU/m3. In terms of odor intensity, the predicted 1hr average was 0.6~0.9 and the 24hr average was 0.2~0.4.

The present study is undertaken to evaluate the effect of volume fraction on the results of Charpy impact test for the rubber matrix filled with nano sized silica particles composites. The Charpy impact tests are conducted in the temperature range 0°C and –10°C. The range of volume fraction of silica particles tested are between 11% to 25%. The critical energy release rate GIC of the rubber matrix composites filled with nano sized silica particles is affected by silica volume fraction and it is shown that the value of GIC decreases as volume fraction increases. In regions close to the initial crack tip, fracture processes such as matrix deformation, silica particle debonding and delamination, and/or pull out between particles and matrix which is ascertained by SEM photographs of Charpy impact fracture surfaces.

In this study, to confirm the effect of alloying elements on the phase transformation and conditions of the friction stir process, we processed two materials, SS400 and SM45C steels, by a friction stir process (FSP) under various conditions. We analyzed the mechanical properties and microstructure of the friction stir processed zone of SS400 and SM45C steels processed under 400RPM - 100mm/min conditions. We detected no macro (tunnel defect) or micro (void, micro crack) defects in the specimens. The grain refinement in the specimens occurred by dynamic recrystallization and stirring. The microstructure at the friction stir processed zone of the SS400 specimen consisted of an α-phase. On the other hand, the microstructure at the friction stir processed zone of the SM45 specimen consisted of an α-phase, Fe3C and martensite due to a high cooling rate and high carbon content. Furthermore, the hardness and impact absorption energy of the friction stir processed zone were higher than those of base metals. The hardness and impact absorption energy of FSPed SM45C were higher than that of FSPed SS400. Our results confirmed the effect of alloying elements on the phase transformation and mechanical properties of the friction stir processed zone.

Experiments for catch and cluster analysis on the catch by gillnet for the Pacific herring were conducted using traditional nylon net (PA) and developing biodegradable net (PBS) with different monofilaments of #2 (=0.23 mm) and #3 (=0.28 mm) in diameter between 2011 and 2012, and of #2, #2.5 and #3 in 2013 in the eastern coastal waters of Samcheok, Korea. The total catch during the experiments was 3,337kg in weight and 16,757 individuals in number. Though the catch ratio of the Pacific herring in 2011 and 2012 was 97.4% and 98.7%, respectively, that of the Pacific herring in 2013 was 73.6% as the biggest and followed by goldeye rockfish (8.6%), black edged sculpin (8.4%), atka mackerel (7.2%) and Alaska cod (1.0%). The ANOVA analysis on the total catch in relation to net material showed that there was not statistically significant difference at the 5% level between nylon net (PA) and biodegradable net (PBS) (p=0.91). With the cluster analysis on the catch in relation to net material (PA, PBS) and twine thick (#2, #3), it showed the influence of net material on the catch was greater than that of twine diameter in this experiment. From the test of homogeneity on the catch by the gillnet with PA and PBS in which several species were caught in 2013, there was not statistically significant homogeneity in relation to net material (p<0.005). That meant the traditional gillnet of nylon (PA) was more efficient than the biodegradable (PBS) gillnet to catch several kinds of fish, however the PBS gillnet was better than the PA gillnet to catch the target Pacific herring.

Graphite can be classified into natural graphite from mines and artificial graphite. Due to its outstanding properties such as light weight, thermal resistance, electrical conductivity, thermal conductivity, chemical stability, and high-temperature strength, artificial graphite is used across various industries in powder form and bulk form. Artificial graphite of powder form is usually used as anode materials for secondary cells, while artificial graphite of bulk form is used in steelmaking electrode bars, nuclear reactor moderators, silicon ingots for semiconductors, and manufacturing equipment. This study defines artificial graphite as bulk graphite, and provides an overview of bulk graphite manufacturing, including isotropic and anisotropic materials, molding methods, and heat treatment.

태양전지는 태양복사에너지를 반도체의 광전효과를 통해 전기에너지로 변환시키는 친환경 에너지변환장치를 의미한다. 수분을 포함하는 다양한 화학물질들에 대한 높은 차단성을 갖는 다층형 필름인 백시트는 태양전지의 중요한 요소이다. 대표적인 백시트는 polyvinyl fluoride (PVF)와 poly(ethylene terephthalate) (PET)의 다층필름으로 구성된다. PVF는 높은 내후성을 가지는 반면, 가격이 상대적으로 비싼 단점을 보인다. 따라서, 백시트의 제조가격을 낮출 수 있으면서, 동시에 실제 태양전지모듈에 적용할만한 수명특성을 만족시킬 수 있는 대체소재의 개발이 필수적이다. 본 연구에서는 일정수준의 결정성을 갖는 PET 필름을 PVF 필름 대신 사용하였다. 그러나, PET 소재는 다양한 pH 조건에서 trans-esterification 및 가수분해에 의해 분해될 수 있기 때문에, 태양전지의 구동조건에서 PET의 분해거동을 이해할 필요가 있다. 단시간 내 화학적 분해거동을 평가하기 위해서, 가속화된 PET 분해실험 프로토콜이 개발되었다. 마지막으로, 제안 개념의 효용성은 태양전지모듈의 장기운전성능 평가를 통해 확인하였다.

In order to prepare anode materials for high power lithium ion secondary batteries, carbon composites were fabricated with a mixture of petroleum pitch and coke (PC) and a mixture of petroleum pitch, coke, and natural graphite (PCNG). Although natural graphite has a good reversible capacity, it has disadvantages of a sharp decrease in capacity during high rate charging and potential plateaus. This may cause difficulties in perceiving the capacity variations as a function of electrical potential. The coke anodes have advantages without potential plateaus and a high rate capability, but they have a low reversible capacity. With PC anode composites, the petroleum pitch/cokes mixture at 1:4 with heat treatment at 1000 oC (PC14-1000C) showed relatively high electrochemical properties. With PC-NG anode composites, the proper graphite contents were determined at 10~30 wt.%. The composites with a given content of natural graphite and remaining content of various petroleum pitch/cokes mixtures at 1:4~4:1 mass ratios were heated at 800~1200 oC. By increasing the content of petroleum pitch, reversible capacity increased, but a high rate capability decreased. For a given composition of carbonaceous composite, the discharge rate capability improved but the reversible capacity decreased with an increase in heat treatment temperature. The carbonaceous composites fabricated with a mixture of 30 wt.% natural graphite and 70 wt.% petroleum pitch/cokes mixture at 1:4 mass ratio and heat treated at 1000 oC showed relatively high electrochemical properties, of which the reversible capacity, initial efficiency, discharge rate capability (retention of discharge capacity in 10 C/0.2 C), and charge capacity at 5 C were 330 mAh/g, 79 %, 80 %, and 60 mAh/g, respectively.

본 연구는 고추 논 비가림 재배시 피복 재료가 생육, 수량 및 dehydrogenase 활성 등에 미치는 영향을 구명하고자 충북 괴산군 농가포장에서 2012년부터 2013년까지 2년간 수행하였다. ‘독야청청(신젠타종묘)’ 품종을 사용하였으며, 멀칭용 피복 재료는 배색비닐, 흑색비닐, 생분해필름, 부직포 등 4처리를 하였다. 1. 피복 재료에 따른 고추의 초장, 주경장, 분지수, 엽장, 엽폭은 통계적인 유의성을 나타내지 않았다. 2. 고추 재배기간 지온은 오전 7시경에 가장 낮았고, 오후 5 ~ 6시경에 가장 높았다. 지온은 배색비닐, 흑색비닐, 생분해 필름, 부직포 순으로 높았다. 3. 생분해필름은 정식 후 60일부터 분해가 시작되었고, 정식 후 120일에는 80% 분해되었다. 4. 피복 재료에 따른 생과중과 건조중은 처리간에 유의성을 나타내지 않았다. 5. ASTA 값은 생분해필름에서 44.6으로 가장 높았고, 배색필름, 흑색필름, 부직포 순으로 높았다. 6. 정식 후 120일의 dehydrogenase 활성은 생분해필름>부직포 >흑색필름 >배색필름 순으로 높았다. 7. 토양 biomass C 함량은 정식 후 80일보다 정식 후 120일에 더 높았다. 8. 피복 재료에 따른 역병, 진딧물류, 담배나방, 응애류, 총채벌레류, 담배가루이의 발생 양상은 차이가 없었다. 결론적으로, 고추 논 재배시 멀칭용 피복 재료에 따른 생육과 수량은 차이를 나타내지 않았다. 생분해필름이 dehydrogenase 활성과 biomass C 함량이 높아 친환경적이고 필름 수거 노력이 필요하지 않아 노동력 절감할 수 있다. 따라서, 생분해필름을 영농에 활용을 적극적으로 검토해야 시점이며, 이러한 결과들은 관련 분야 산업의 활성화에 기여할 것으로 생각된다.

Ti alloys are extensively used in high-technology application because of their strength, oxidation resistance at high temperature. However, Ti alloys tend to be classified very difficult to cut material. In this paper, The powder synthesis, spark plasma sintering (SPS), bulk material properties such as electrical conductivity and thermal conductivity are systematically examined on Ti2AlN and Ti2AlC materials having most light-weight and oxidation resistance among the MAX phases. The bulk samples mainly consisted of Ti2AlN and Ti2AlC materials with density close to theoretical value were synthesized by a SPS method. Machining characteristics such as machining time, surface quality are analyzed with measurement of voltage and current waveform according to machining condition of micro-electrical discharge machining with micro-channel shape.

The finite element stress analysis of large sized rectangular water tank structures made of stainless steel materials is carried out for various combined load cases. The combined load cases for a large size of 5,000ton are further determined using the specification(KS B　6283) established from the Korean Standards Association. The changed water capacity due to the size of reservoirs could be heavily dependent for evaluating seismic effects, especially for large reservoirs. For the better numerical efficiency, the rectangular panels are modelled using the ANSYS ADPL module. The numerical results obtained for different load cases mainly show the effect of the interactions between the different load combination and other various parameters, for example, the water capacity, and different stainless steel materials. The structural performance for various load combinations is also evaluated.

단감을 재배하는 농가에서 저장성을 향상 시킬 수 있는 값싸고 쉬운 방법을 개발하기 위해 본 연구를 수행 했다. 농가 관행 LDPE 포장재 내에 동봉할 수 있는 천연소재(대나무활성숯, 왕겨숯, 겔라이트)를 선발하여 상온과 저온환경에서 가용성 고형물 함량, 경도, 식미, 부패도, 연화도의 변화를 1주일 또는 2주일 간격으로 조사 하였다. 대나무활성숯을 동봉한 LDPE 포장 방법이 단순 LDPE 포장 방법 보다 저장성 및 품질을 을 좋게 유지하였다. 대나무활성숯을 동봉한 LDPE 포장 방법은 관행 농법 농가와 유기 농법 농가 모두에서 장기 저장 시 그리고 유통 중 온도변화 시 저장성을 향상 시킬수 있는 값싸고, 손쉬운 방법으로 활용할 수 있을 것으로 판단된다.

Currently there are two main categories of soft contact lens materials available in the market namely hydrogels and silicone hydrogels. This article provides a summary of the pros and cons of these materials and suggests a new type of material that could be a new direction for material development moving forward. Hydrogel lenses are biocompatible, hydrophilic, comfortable to wear, and have excellent optical properties. However, the oxygen transmissibility (Dk/t) of hydrogel lenses is limited by its water content and the lens thickness. A higher percentage of water will provide greater oxygen transmissibility but high water content materials are also more prone to dehydration. Silicone hydrogels (Si-hys) were first introduced in 1999. Silicone was added to hydrogel to increase the oxygen permeability and eye care professionals had hoped that this material can resolve most of the issues related to contact lens wear. Si-hys have offered multiple times increase in Dk/t over hydrogels, but they have not reduced the incidence of microbial keratitis nor contact lens drop-out rate. In addition, si-hys are not perfect for every patient, they are generally stiffer (with higher modulus) and are more likely to induce ocular complications due to its mechanical properties. Si-hy lenses are also associated with lens surface issues and an increased risk of infiltrative events. The addition of silicone does not seem to be without problems. Si-hy is an important step, but not a big leap and definitely not the only choice for our patients. A new material called Hypergel was developed using the concept of bio-inspiration. Scientists have learnt from the eye and applied three bio-inspired features to make the material works like the eye. Firstly, hypergel has 78% of water content and that matches the water content of the cornea. Secondly, it meets the oxygen level the open eye needs to maintain healthy white eyes. Thirdly, it mimics the lipid layer of the tear film to prevent dehydration. Without the addition of silicone, this material can meet the oxygen need of the open eye and can resist dehydration.

Purpose : Recently, the eye disease associated with ultraviolet radiation were reported. In this study, the UV-block hydrophilic soft contact lens using 2-ethylhexyl trans-4-methoxy-cinnamate were manufactured and the optical properties of copolymerized materials were measured. Methods: The basic hydrophilic soft contact lens material with addition of Dhb(2,4-dihydroxy benzophenone) 0.5% ~ 1.0%, Thb(2,4,4-trihydroxy benzophenone) 0.5% ~ 1.0% and Hmb(2-hydroxy-4-methoxy benzophenone) 0.5% ~ 1.0% respectively were polymerized and the hydrophilic soft contact lens were manufactured by cast mould method. The lenses were stored in a 0.9% NaCl normal saline for analysis. Results: In the measurement of DHB samples, the optical transmittance showed the UV-B transmittance of 2.1 ~ 4.3%, UV-A transmittance of 19.0 ~ 27.2% and visible transmittance 88.8 ~ 90.1%. And also, in the case of THB samples, the optical transmittance of UV-B, UV-A and visible transmittance was 2.0 ~ 2.4%, 13.6 ~ 18.8% and 89.5 ~ 90.9%, respectively. Also, in the case of HMB samples, the optical transmittance of UV-B, UV-A and visible transmittance was 4.0 ~ 12.3%, 22.5~37.2% and 87.9 ~ 89.2%, respectively. Conclusions: Based on the results of this study, 2-ethylhexyl trans-4-methoxy-cinnamate with benzophenone materials were suitable for use as a material to UV-block hydrophilic lens.

본 연구에서는 Montmorillonitrile(MMt)계 무기물을 이용하여 SPAES고분자에 첨가한 후 제조된 용액을 이용하여 복합막을 제조하였으며 특성평가가 진행되었다. 순수한 MMt의 경우 고분자에 첨가되었을 경우 측유의 실리케이트층 구조로 인해 메탄올 투과도는 감소하나 이온전도도가 감소되는 문제점을 가지고 있으므로 본 연구에서는 MMt를 유기화 시켜 최적화된 메탄올 투과도와 이온투과도를 가지는 무기물을 제조하고자 하였으며 최종적으로 제조된 분리막의 특성평가를 진행하였다.

Photovoltaic (PV) modules are environmentally energy conversion devices to generate electricity via photovoltaic effect of semiconductor from solar energy. One of key elements in PV modules is “backsheet,” a multilayered barrier film. A desirable backsheet should exhibit barrier properties. A representative backsheet materials is composed of polyvinyl fluoride (PVF) and poly(ethylene terephthalate) (PET). In this study, we utilize PET films with high crystallinity, instead of PVF. Since it is well known that PET is suffering from hydrolysis, it is needed to understand PET decomposition behavior. To evaluate their hydrolysis behavior, accelerated PET decomposition test protocols are used. Electro chemical PV module performances are investigated to prove the efficacy of hydrolyticall durable PET films selected via the screening process.

Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of 700°C-1000°C for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of 900°C, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.

고분자의 용이한 가공성과 우수한 투명성, 그리고 합리적인 비용 효율로 인해 식품 포장 산업에서 금속이나 유리용기들을 고분자 기반의 포장 소재들로 대체하려는 경향이 전 세계적으로 널리 퍼지고 있다. Barrier 고분자들은 산소, 이산화탄소, 수증기 등 대기 가스에 대한 낮은 투과성을 나타내고 있어 식품 포장 산업 이용에 유용하다. 이러한 식품 포장 산업의 전반적인 추세와 함께, 산소에 민감한 주스, 착향 음료, 그리고 에너지 음료 등 새로운 식품 산업의 성장으로 인해 고성능의 barrier 특성, 특히 O2와 CO2에 대해 낮은 투과성을 지닌 고분자 포장 소재의 개발이 시급한 상황이다. 기존의 고분자에 기반한 barrier의 성능 향상은 새로운 식품 포장 산업에 급격한 변화를 줄 것이다. 본 총설에서는 (1) antiplasticization을 유도한 barrier 소재들, (2) antiplasticization과 crystallization을 사용한 barrier 성능 상승 효과, (3) 새로운 barrier 고분자들, (4) 나노합성 소재, (5) 혼합 고분자 등과 더불어, 차세대 포장 소재들의 특성 분석을 소개하고자 한다.

To evaluate system reliability of a composite structure consisting of more than two structural members, it is necessary to identify that the members are connected to each others in parallel or in serial. Especially for parallel composite system, it is also necessary to confirm that mechanical properties of materials for the members are brittle or ductile. For parallel system of brittle materials, if one part fails, that part cannot resist load anymore and the whole load transfers to the other part. However, for parallel system of perfectly plastic materials, if one part fails, that part can maintain the amount of its maximum load capacity and the remaining load transfers to the other part. In this study, a methodology to determine reliability index for composite structures consisting of quasi-brittle materials. By assuming quasi-brittle materials as brittle or perfectly plastic materials, the upper and lower bounds of the reliability index can be determined. The reliability index for parallel system of quasi-brittle materials is then determined by interpolating the upper and lower bounds indices using ductility number extracted from stress-strain curves of quasi-brittle materials.

The repellent activities of 33 plant extracts against Aedes albopictus were examined using a patch test for adult. The six plant extracts (Magnolia denudate, Dryopteris crassirhizoma, Cnidium officinale, Lindera obtusiloba, Magnolia kobus, and Houttuynia cordata) showed over 70% repellency activities to Ae. albopictus. The insecticidal activity of Curcuma longa against Ae. albopictus was also determined. C. longa hexane extraction showed 100% larvicidal activity at 1,000 ppm after treated 24 h. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 fraction gave 100% mortality to Ae. albopictus at 100 ppm. H12 fraction was determined 87.8% larvicidal activity to Ae. albopictus at 50 ppm. Active constituent was analysed as the sesquiterpene, ar-turmerone (C15H20O) by GC and GC-MS. C. longa extract gave highly protection against mosquito bites. The hexane extraction showed complete protection at 10 mg over 6 h. In this study, the sesquiterpene from C. longa induced a protection time, repellency, landing time, and biting time against Ae. albopictus. These results suggest that the some plant extracts and C. longa have the potential to be used an eco-friendly materials for the control of mosquitoes.