• Applied Chemistry for Engineering
• /
• v.31 no.3
• /
• pp.284-290
• /
• 2020

Energetic thermoplastic elastomers (ETPEs) based on glycidyl azide polymer (GAP) and carboxylated GA copolymers [GAP-ETPE and poly(GA-carboxylate)-ETPEs] were synthesized using isophorone diisocyanate (IPDI), dibutyltin dilaurate (DBTDL), 1,4-butanediol (1,4-BD), and soft segment oligomers such as GAP and poly(GA-carboxylate). The synthesized GAP-ETPE and poly(GA-carboxylate)-ETPEs were characterized by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), calorimetry and sensitivity towards friction and impact. DSC and TGA results showed that the introduction of carboxylate group in GAP helped to have better thermal properties. Glass transition temperatures of poly(GA-carboxylate)-ETPEs decreased from -31 ℃ to -33 ℃ compared to that of GAP-ETPE (-29 ℃). The first thermal decomposition temperature in poly(GA_0.8-octanoate_0.2)-ETPE (242 ℃) increased in comparison to that of GAP-ETPE (227 ℃). Furthermore, from calorimetry data, poly(GA-carboxylate)-ETPEs exhibited negative formation enthalpies (-6.94 and -7.21 kJ/g) and higher heats of combustion (46713 and 46587 kJ/mol) compared to that of GAP-ETPE (42,262 kJ/mol). Overall, poly(GA-carboxylate)-ETPEs could be good candidates for a polymeric binder in solid propellant due to better energetic, mechanical and thermal properties in comparison to those of GAP-ETPE. Such properties are beneficial to application and processing of ETPE.

• Korean Journal of Environmental Agriculture
• /
• v.23 no.3
• /
• pp.128-132
• /
• 2004

Ozone effects were studied by plant growth chamber to evaluate the impact of ozone ($O_3$) on the physiology of two hot pepper, Capsicum annuum L., cultivars, 'Dabotab' and 'Buchon'. Forty-day old plants with $5{\sim}7$ leaves were exposed to $O_3$ of <20 and 150 nL/L for 8h/d for 3 days. Net photosynthesis and stomatal conductance were measured and foliar injury was described. Foliar damage due to the treated $O_3$ was different from the varieties. 'Dabotab' was most sensitive to $O_3$ and 'Buchon' was resistant. Symptom of ozone damage on the leaves was bifacial necrosis. Decreases of net photosynthesis by $O_3$ were 56% and 40% on 'Dabotab' and 'Buchon', respectively. Decreases of stomatal conductance by $O_3$ were 66% and 63% on each variety. $O_3$ damage on net photosynthesis was started at the low levels of light on the two hot peppers. In addition, assimilation-internal $CO_2$ concentration curves were not different from the two varieties. In conclusion, $O_3$ closed the stomata and decrease net photosynthesis on hot peppers regardless of the ozone sensitivity on leaf injury, but the difference of ecophysiological responses between the two varieties was not found clearly.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.16 no.1
• /
• pp.147-157
• /
• 2013

Rice is a main crop and rice field is the most important farmland in Korea. This study was conducted to propose the methodology assessing impact and vulnerability on rice production by climate change at the regional and national level in Korea. We evaluated a vulnerability of rice paddy according to the outbreak of a main disease and pest of a rice plant. As results, Jeju-do, Gyeongsangnam-do, and Jeollanam-do were more vulnerable area than others. In contrast, the southern central region including Gyeonggi-do was less vulnerable than others. The vulnerable index was significantly higher in 2050s (0.5589) than in present (0.3500). This result showed that the vulnerable to the disease and pest enlarge in the future. The adaptive capacity highly contributed to the vulnerability assessment index. The daily maximum temperature of June and the daily average temperature from May to August also contributed the climate exposure index. The area of occurring sheath blight, rice leaf blast and striped rice borer was related to the system sensitivity index. The ability of water supply (readjustment area of arable land per paddy field area) and rice production technique (rice yield per hectare) were the highly contributed variables to the adaption capacity index.

• Korean Journal of Clinical Pharmacy
• /
• v.26 no.1
• /
• pp.59-69
• /
• 2016

Background: The subcutaneous formulation of biologic disease-modifying antirheumatic drugs (DMARDs) was preferred due to favored self-administration and would be an economical treatment option for patients with rheumatoid arthritis. This study was to compare the economic impact of biologic DMARDs administered by subcutaneous injection in patients with rheumatoid arthritis who had inadequate response to conventional DMARDs. Methods: The cost-minimization analysis was conducted to estimate the lifetime health care costs of treatment sequences with subcutaneous biologic DMARDs as first-line therapy from a health care system perspective. The Markov model was developed to represent the transitions through treatment sequences based on American College of Rheumatology response rate and discontinuation rate. The health care costs comprised the cost of medications, administration, dispensing, outpatient visits, test/diagnostic examination, palliative therapy and treatment of serious infection. All costs were expressed in 2016 Korean Won (KRW) and discounted at 5%. Results: The mean lifetime health care cost per patient was lowest in the etanercept sequence, which was estimated at KRW 63,441,679. The incremental costs of the treatment sequence started with adalimumab, golimumab, abatacept, and tocilizumab were KRW 7,985,730, KRW 4,064,669, KRW 2,869,947, and KRW 4,282,833, respectively, relative to etanercept sequence. These differences in costs mainly were attributable to medication costs. One-way and probabilistic sensitivity analyses confirmed that etanercept represented the option with the lowest cost compared with comparators. Conclusion: This study found that etanercept is likely a cost-saving treatment option among subcutaneous biologic DMARDs in patients with rheumatoid arthritis.

• Journal of Hydrogen and New Energy
• /
• v.25 no.2
• /
• pp.173-182
• /
• 2014

Dimethyl ether (DME) is a new clean fuel as an environmentally-being energy resources. DME has similar characteristics to those of LPG and can be substituted Diesel fuel. KOGAS has investigated and developed new innovative DME synthesis process from synthesis gas with KOGAS's own technologies. KOGAS had finished the construction of 10ton/day DME demonstration plant in 2008, we have established the basic design of commercial plant which can produce 3,000ton/day DME. Specifically, an economic model for a commercial DME project will be presented. It accounts for all the major cost factors that are considered in a commercial scale project as the model input for performing cash flow analysis, after which key economic indicators are produced including the internal rate of return (IRR), net present value (NPV). Sensitivity analysis is performed to identify dominant cost factors to the project economics and quantify their impact. The inputs to the economic analysis will be based on representative cost factors from the commercial-scale design of KOGAS' direct DME process supplemented by literature data. Case study results will be presented based on recent commercialization projects.

• Earthquakes and Structures
• /
• v.11 no.6
• /
• pp.1123-1141
• /
• 2016

To explore the application of traditional tuned mass dampers (TMDs) to the earthquake induced vibration control problem, a pounding tuned mass damper (PTMD) is proposed by adding a viscoelastic limitation to the traditional TMD. In the proposed PTMD, the vibration energy can be further dissipated through the impact between the attached mass and the viscoelastic layer. More energy dissipation modes can guarantee better control effectiveness under a suite of excitations. To further reduce mass ratio and enhance the implementation of the PTMD control, multiple PTMDs (MPTMD) control is then presented. After the experimental validation of the proposed improved Hertz based pounding model, the basic equations of the MPTMD controlled system are obtained. Numerical simulation is conducted on the benchmark model of the Canton Tower. The control effectiveness of the PTMD and the MPTMD is analyzed and compared under different earthquake inputs. The sensitivity and the optimization of the design parameters are also investigated. It is demonstrated that PTMDs have better control efficiency over the traditional TMDs, especially under more severe excitation. The control performance can be further improved with MPTMD control. The robustness can be enhanced while the attached mass for each PTMD can be greatly reduced. It is also demonstrated through the simulation that a non-uniformly distributed MPTMD has better control performance than the uniformly distributed one. Parameter study is carried out for both the PTMD and the MPTMD systems. Finally, the optimization of the design parameters, including mass ratio, initial gap value, and number of PTMD in the MPTMD system, is performed for control improvement.

• Composites Research
• /
• v.23 no.3
• /
• pp.64-68
• /
• 2010

Expanded polystyrene(EPS) foams are often used in packaging to protect electrical appliances from impact loads. The energy absorbing performances of the EPS foams depend on several parameters such as density, microstructure and strain rate. Thus, the effects of the parameters on the strength of the EPS foams need to be investigated for an optimized packaging design by FEM. In this study, various EPS foams which have different densities were quasi-statically and dynamically loaded in order to obtain the stress-strain curves. EPS foams of various densities from 18.5 to 37.0kg/m3 were considered in the experiments. A drop-mass type apparatus was developed for the intermediate strain rate tests up to several hundreds/second. It was found from the experimental results that the strength of the EPS foams increase about 170% as the strain rate increases from 0.06/s to 60/s. Experimental results also showed that the strain rate sensitivity increases as the strain increases.

• Asian-Australasian Journal of Animal Sciences
• /
• v.28 no.5
• /
• pp.716-729
• /
• 2015

Small-scale household digesters have been promoted across Asia as a sustainable way of handling manure. The major advantages are that they produce biogas and reduce odor. However their disadvantages include the low recycling of nutrients, because digestate is dilute and therefore difficult to transport, and the loss of biogas as a result of cracks and the intentional release of excess biogas. In this study, life cycle assessment (LCA) methodology was used to assess the environmental impacts associated with biogas digesters in Vietnam. Handling 1,000 kg of liquid manure and 100 kg of solid manure in a system with a biogas digester reduced the impact potential from 4.4 kg carbon dioxide ($CO_2$) equivalents to 3.2 kg $CO_2$ equivalents compared with traditional manure management. However, this advantage could easily be compromised if digester construction is considered in the LCA or in situations where there is an excess of biogas which is intentionally released. A sensitivity analysis showed that biogas digesters could be a means of reducing global warming if methane emissions can be kept low. In terms of eutrophication, farms with biogas digesters had 3 to 4 times greater impacts. In order to make biogas digesters sustainable, methods for recycling digestates are urgently required.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.9
• /
• pp.5495-5501
• /
• 2013

Background: Alu elements are one of the most common repetitive sequences that now constitute more than 10% of the human genome and potential targets for epigenetic alterations. Correspondingly, methylation of these elements can result in a genome-wide event that may have an impact in cancer. However, studies investigating the genome-wide status of Alu methylation in cancer remain limited. Objectives: Oral squamous cell carcinoma (OSCC) presents with high incidence in South-East Asia and thus the aim of this study was to evaluate the Alu methylation status in OSCCs and explore with the possibility of using this information for diagnostic screening. We evaluated Alu methylation status in a) normal oral mucosa compared to OSCC; b) peripheral blood mononuclear cells (PBMCs) of normal controls comparing to oral cancer patients; c) among oral epithelium of normal controls, smokers and oral cancer patients. Materials and Methods: Alu methylation was detected by combined bisulfite restriction analysis (COBRA) at 2 CpG sites. The amplified products were classified into three patterns; hypermethylation ($^mC^mC$), partial methylation ($^uC^mC+^mC^uC$), and hypomethylation ($^uC^uC$). Results: The results demonstrate that the $%^mC^mC$ value is suitable for differentiating normal and cancer in oral tissues (p=0.0002), but is not significantly observe in PBMCs. In addition, a stepwise decrease in this value was observed in the oral epithelium from normal, light smoker, heavy smoker, low stage and high stage OSCC (p=0.0003). Furthermore, receiver operating characteristic (ROC) curve analyses demonstrated the potential of combined $%^mC$ or $%^mC^mC$ values as markers for oral cancer detection with sensitivity and specificity of 86.7% and 56.7%, respectively. Conclusions: Alu hypomethylation is likely to be associated with multistep oral carcinogenesis, and might be developed as a screening tool for oral cancer detection.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.10
• /
• pp.1551-1558
• /
• 2001

Recently, a number of underground pipelines have been drastically increased. The integrity of these buried pipelines, especially gas transmitting pipelines, is of importance due to an explosive characteristic of natural gas. The third party damage is known as one of the most critical factor which causes fatal accidents. For this reason, a number of systems detecting third party damage are under development. The major concern in the development of third party damage detection system is to transmit vibration signals out of accelerometer to signal conditioner and data acquisition system without any interference caused by noise. The objective of this paper is to develope a fiber optic accelerometer applicable to third party damage detection system. A fiber optic accelerometer was developed by use of combining principles of one degree of freedom vibration model and an extrinsic Fabry-Perot interferometer. The developed fiber optic accelerometer was designed to perform with a sensitivity of 0.06mVg, a frequency range of less than 6kHz and an amplitude range of -200g to 200g. The developed, accelerometer was compared with a piezoelectric accelerometer and calibrated. In order to verify the developed accelerometer, the field experiment was performed. From the field experiment, vibration signals and the location of impact were successfully detected. The developed accelerometer is expected to be used for the third party damage detection system which requires long distance transmission of signals.