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.

『Act on Facilitation of Purchase of Small and Medium Enterprise – Manufactured Products and Support for Development of Their Markets』 was created and implemented. The act states that the materials designated by the Small and Medium Business Administration are directly purchased from the small and medium enterprises and provided to the construction companies so that the materials can be provided as GFGI (Government Furnished and Government Installed) in the case of a public construction project. This thesis is aimed to analyze the current status on the problems of each project party and understand their improvement requests so that mutually beneficial plans can be sought and improved process is presented for the continuous development of the direct construction material purchase system as well as successful construction projects. And This thesis summarized the purpose of the institutions and their change histories, and related law as well as codes for the better understanding of administrative procedures for the purchase system and the analyses as well as the improved process on the difficulties in complying with the current institutions.

The objective of this study is to censure the provision of correct information to the public through investigating radon emanation by building materials that are used in domestic construction environment. Radon emanation has been identified in 10 framing materials and 16 finishing materials of 26 building materials used in the domestic construction-industry. Radon emanation was measured using the closed chamber method based on CR-39 nuclear track detectors(NTDs). On Brick-General in framing materials, the highest radon emanation rates were 0.60028 Bq/ m2·h for surface and 0.00733 Bq/kg·h for mass, while on Ceiling-Tex Cement Plaster in finishing materials. The highest radon emanation rates were 0.47708 Bq/m2·h for surface and 0.05885 Bq/kg·h for mass.

This study performed a finite element crash analysis of support structures made of various composite materials for road facilities. The effects of different material properties of composites for various parameters are studied using the finite element commercial package for this study. In this study, the existing finite element analysis of composite post structures using the LS-DYNA program is further extended to compare dynamic behaviors against car crash of the structures made of various composite materials. The several numerical examples show the comparison of the nonlinear dynamic effects for different materials.

In this paper, a finite element dynamic simulation study was performed to gain an insight about the blast wall test details for the offshore structures. The simulation was verified using qualitative and quantitative comparisons for different materials. Based on in-depth examination of blast simulation recordings, dynamic behaviors occurred in the blast wall against the explosion are determined. Subsequent simulation results present that the blast wall made of high energy absorbing high manganese steel performs much better in the shock absorption. In this paper, the existing finite element shock analysis using the LS-DYNA program is further extended to study the blast wave response of the corrugated blast wall made of the high manganese steel considering strain rate effects. The numerical results for various parameters are verified by comparing different material models with dynamic effects occurred in the blast wall from the explosive simulation.

Extracts from Aloe vera leaves, Aloe arborescens leaves, Aloe vera callus, Portulaca oleracea and cacao (Theobroma cacao L.) bean husk (CBH) were prepared using acetone, chloroform, ethanol, hexane, and water. Solvent extracts of Aloe vera leaf had very high antioxidant activities showing IC50 values in the ranges of 0.02-0.17 mg/ mL, and had the highest total phenolic and flavonoid content among the tested samples. We hypothesized that Aloe vera leaf and CBH extracts might possess considerable in vitro anti-glycation activities. Indeed, these extracts strongly inhibited the formation of advanced glycation end-products from RNase in the presence of ribose. The chloroform extract of Aloe vera leaf showed the strongest inhibition of AGE formation (99.9%), followed by the 95% acetone extract (92.8%) at a concentration of 1 mg/mL, exhibiting higher anti-glycation activities than those of AG and rutin (73.4% and 96.1% at 1 mg/mL, respectively). The anti-glycation activity of all extracts was correlated positively with their total contents of phenolics and flavonoids. We conclude that Aloe vera leaf extracts and their constituents may be used as anti-glycation agents.

이 글은 신라가 최초의 주(州)를 설치한 실직의 고고자료를 검토하고, 실직의 신라사적인 의미를 찾아보는데 있다. 이러한 목적을 달성하기 위하여 실직 지역의 고고학적 발굴성과를 비판적으로 검토․수용하여 기본적이고 객관적인 고고자료부터 확보하였다. 그리하여 실직 지역의 고고자료 가운데 신라산성과 신라고분을 추출하였다. 나아가 이를 토대로 신라사에서 차지하는 실직의 역사적인 역할을 찾아 보았다. 시간적으로는 5~6세기가 중심 시기가 된다. 이 시기는 이전 시기에 비하여 문헌사료가 풍부한 편이고, 동시에 사료 비판을 통해 삼국의 쟁패와 관련한 역사적 실상에 접근할 수 있다. 이 때 고고자료가 사료 비판과 역사적 해석에 크게 기여할 수 있으며, 그러한 장점을 활용할 수 있는 좋은 시기이기도 하다. 공간적으로는 통일신라시대의 행정구역을 기본으로 하였다. 즉 실직의 고고자료는 통일신라시대 삼척군의 군치인 지금의 삼척시와 속현 지역을 포함하여 살펴보 았다. 󰡔삼국사기󰡕 지리지에 의하면 통일신라시대 삼척군의 속현에 지금의 강릉시 옥계면인 우계현이 포함되므로 동해시와 강릉시 옥계면을 실직의 범위에 포함시키고, 연구 범위로 삼았다. 그 결과 실직의 고고학적 양상을 정리하면 신라산성으로는 오십천 하구의 곶 (串)에 위치한 오화리산성이 가장 가능성이 높다고 보았고, 고분문화로는 5세기 3/4분기인 황남대총 남분 단계 직전에 신라문화가 출현하였으며 5세기 4/4분 기~6세기 1/4분기에 고분군이 급증․확산하는 양상을 보이는 것을 알 수 있었다. 고분군의 입지도 구릉지대와 산의 사면에 분포하는 특징을 보여 사구지대에 초기 고분이 분포하는 강릉지역과 차이를 보이고 있다. 필자는 이들 시․공간적인 고고자료와 문헌사료, 역사지리적 자료들을 활용하여 신라의 실직 경영에 대한 신라사적 의미를 찾는 시도를 하였다. 그리하여 오화리 산성의 경우 신라계 지명인 벌 지명이 있고, 건너편인 정라진 일대도 부리(=벌) 지명이 남아 있어 오십천 하구 일대가 신라마을이 형성된 실직의 핵심 지역으로 판단하였다. 나아가 통일신라 중사의 하나인 북해 비례산도 오십천 하구인 정라진 바닷가 일대와 오화리산성일 가능성이 높다고 추정하였다. 결론적으로 신라는 중원(충주)을 거점으로 남한강을 따라 동해안의 강릉이나 삼척을 측방공격하는 고구려군을 막는 방어의 거점성이자 해양의 거점으로 오십천 하구에 있는 오화리산성을 운용하였던 것이다. 이와 같이 신라인들이 동시대부터 삼척의 오십천 하구 일대를 해양의 거점으로 인식하고 있었기 때문에 신라통일기에도 중사의 사해에 포함시켰다고 볼 수 있겠다.

Adhensively bonded joints in dissimilar materials have been widely applied in various engineering fields such as automobiles, space vehicle, semiconductor, vessel. To establish a fracture criterion and a reasonable strength evaluation method on adhensively interfaces in dissimilar materials, it is necessary to assess fracture parameters with various bonding conditions. In this paper, through stress analysis by using the 2-dimensional elastic boundary element method(BEM), the stress singularity factors on adhensively bonded joint in dissimilar materials were investigated quantitatively, and suggested the strength evaluation method by using fracture parameters

PURPOSES : The objective of this study is to develop new pothole repair materials using polyurethane-modified asphalt binder, and to evaluate them relative to current pothole repair materials in order to improve the performance of repaired asphalt pavement. METHODS : In the laboratory, polyurethane-modified asphalt binder is developed, and then asphalt binder is added to produce pothole repair materials. In order to evaluate the properties of this new pothole repair material, both an indirect tension strength test and a direct tension strength test are performed to measure the material strength and bond strength, respectively. Additionally, the basic material properties are evaluated using the asphalt cold mix manual. The strength characteristics based on curing times are evaluated using a total of 7 types of materials (3 types of current materials, 2 types of new materials, and 2 types of moisture conditioned new materials). The indirect tension strength tests are conducted at 1, 2, 4, 8, 16, and 32 days of curing time. The bond strength between current HMA(Hot Mix Asphalt) and the new materials is evaluated by the direct tension strength test. RESULTS AND CONCLUSIONS : Overall, the new materials show better properties than current materials. Based on the test results, the new materials demonstrate less susceptibility to moisture, faster curing times, and an improved bond strength between HMA and the new materials. Therefore, the use of the new materials reported in this study may lead to enhanced performance of repairs made to asphalt pavement potholes.

무가온 하우스에서 공심채 조기재배시 터널피복재와 파종시기가 생육과 수량에 미치는 영향을 조사하였다. 터널 설치기간(3월 5일~4월 30일, 10월 11일~11월 10일)중 PE필름으로 터널을 피복한 경우 일평균 기온과 지온이 터널을 설치하지 않은 무처리에 비해 각각 2.0~2.4oC, 0.9~1.0oC가 높았고, 일라이트 부직포로 피복한 경우도 각각 1.6~1.8oC, 0.6~0.8oC가 상승했으며 특히, 일중 저온시간대의 온도 상승 효과가 더욱 컸다. PE필름이나 일라이트 부직포로 피복한 터널에서 3월 15일 파종한 경우 출현기간 중 온도는 무처리로 4월 5일 파종한 경우와 비슷한 수준을 보였으며, 출현일수와 출현율도 이와 유사하게 나타났다. 또한 터널피복을 하고 3월 5일이나 3월 15일에 파종한 경우 무처리 4월 5일 파종에 비해 수확가능기간이 길어져 2회 더 수확할 수 있었고, 총 수확량도 22.5~25.7% 증가하였으나, PE필름과 일라이트 부직포간의 유의적인 차이는 나타나지 않았다. 한편, 기온상승에 의한 고온장애 우려로 한낮에는 PE필름을 제거해야 하는 반면, 일라이트 부직포는 이 제거작업이 필요 없었다. 이들 결과를 볼 때, 공심채를 무가온 하우스 에서 조기재배하는 경우 일라이트 부직포를 이용하여 터널을 설치하고 3월 중순에 파종하는 것이 적합한 것으로 판단된다.

Radon is an inert gas, and a naturally occurring radioactive material. Radon is produced by radium and uranium. Generated radon causes lung cancer through the inhalation. Therefore, If uranium contaminated soil is close to indoor spaces, residents may be exposed to this radioactive material(Radon). Generally, radon affects the first to third floors of buildings. But our research team has often detected high radon concentration in the indoor air of high-rise apartments. The reason for this is that building materials containing uranium and radium are brought into apartments. This study was conducted an investigation into the radon emission rate of building materials being used in South Korea. Also, our team conducted an investigation into the radon emission rate of gypsum tiles and concrete found in an apartment(17th floor apartment indoor radon concentration 5.03 pCi/L, Rad- 7(DURRIDGECo.USA)). Finally, we investigated the radon emission rate of bricks containing the soil near a uranium mine. The average radon emission rates of general building materials are as followings: (gypsum board : 0.20·h-1/kg, gravel : 0.05, gypsum tile : 0.02, indoor tile : 0.08, general brick : 0.02, red clay tile : 0.02, concrete : 0.11, uranium mine soil : 4.81). The results regarding the radon emission rate from a 17th floor apartment’s building materials are as followings: (gypsum board : 0.70, concrete : N/A). The results regarding the radon emission rate from bricks containing soil near a uranium mine was 0.19. This experiment indicates that gypsum boards show the highest radon emission rate among general building materials. In particular, the radon emission rate from the gypsum boards in a 17th floor apartment was 3.5 times higher than general gypsum boards. Overall the results suggest that building materials that possess high levels of uranium emit more radon gas than any other materials. South Korea has not established legal regulations on radon emission from building materials. However, the results of this study strongly suggest that it is of the utmost importance to manage the radon emission rate of building materials and control their usage before construction.

선본사의 두 석조문화재 관봉 석조여래좌상과 삼층석탑의 석재들은 암석기재적으로 거의 동일한 특징을 보인다. 즉, 회백색의 조립질로서 반상조직을 보이는 화강암이며, 주 구성광물은 사장석, 알칼리장석, 석영, 흑운모, 각섬석, 녹니석 등으로 이루어져 있다. 이런 기재적 특징들은 선본사가 위치한 팔공산 화강암체 서남부의 화강암 노두에서 확인되는 것과도 유사다. 모드조성에서는 석조여래좌상의 경우 몬조화강암에 속하나 삼층석탑 및 인근 화강암 노두의 암석은 섬장화강암과 몬조화강암의 양쪽 조성을 나타낸다. 전암대자율 측정값을 보면 관봉석조여래좌상, 삼층석탑, 선본사 인근화강암 노두에서 각각 10-14, 10-15, 9-16(×10-3 SI)의 범위를 보여 거의 동일하며, 자철석계열의 팔공산 화강암을 나타낸다. 감마스펙트로미터 측정값에서도 세 암석에서 K, eU, eTh의 함량들이 거의 유사한 범위에 속한다. 결론적으로 선본사의 관봉 석조여래좌상과 삼층석탑은 팔공산 화강암으로 만들어졌으며, 주변 지역의 화강암체가 그 원산지라고 추정된다.