This study was conducted to establish spring sowing techniques in preparation for the impacts of climate change on sowing time and wintering rates of winter forage crops such as barley, oat and IRG. Oat showed the highest yield in 2017 which had relatively dry climate condition. And when sowing in late Febrnary 2017 yielding 9,408kg/ha were obtained, yielding 4,011kg/ha more than IRG's sown in the same period. In 2018 which had relatively wet climate condition, four barley species decreased in the production from the previous year. Oat also had decreased by 70% from 9,408kg/ha to 2,851kg/ha. On the other hand, IRG maintained the production in the mid-5,000kg/ha range. It was also found that IRG had the least variability due to external influences regardless of seeding period for 2 years. Mixed sowing with IRG and oat in 50:50 ratio was the highest dry matter, 6,584kg/ha, and IRG was 18.5% and Oat was 2.3 times higher than single planting.

This study was conducted to investigate the effects by supplementing concentrates during the late fattening phase in TMR (total mixed ration) feeding of Korean steer on the performance, carcass traits, physico-chemical characteristics and sensory test of the longissimus dorsi muscle. Eight Korean steers (24 months of age) averaging 604 kg in body weight were fed the TMR (Control) or the TMR supplemented with concentrates (TMR+conc.) until 30 months of age, then they were slaughtered. Steers fed the TMR supplemented with concentrates had a higher (p<0.05) intakes of dry matter and TDN (total digestible nutrient), carcass weight and marbling score compared to those fed TMR only, but carcass grade did not differ (p>0.05) between treatments. Amino acid concentration of the longissimus dorsi muscle did not differ between treatments, However, the highest concentrations were for glutamic acid and lowest for cystine; further, and the content of essential amino acids was highest for lysine, leucine, threonine, arginine, and isoleucine in that order. Cis-oleic acid and arachidonic acid of fatty acids in the longissimus dorsi muscle were higher (p<0.05) in the control condition compared to TMR+conc. The contents of oleic acids, palmitic acid, stearic acid constituted about 88% of the total fatty acids. Although the physico-chemical characteristics of the longissimus dorsi muscle did not significantly differ between treatments (p>0.05), but the sensory test results were lower for the TMR+conc. condition. These results suggest that supplementing concentrates during the late fattening phase of Korean steers resulted in increasing the carcass weight and marbling score. However, the cis-oleic acid content of the longissimus dorsi muscle was decreased as a result of supplementing concentrates, which could affect negatively in meat sensory evaluation.

Recently, the occurrence frequency of earthquake has increased in Korea, and many cultural assets have been damaged. Cheomseongdae is a valuable cultural assets that must be preserved historically and culturally. But, the masonry structure such as Chemseongdae is vulnerable to lateral forces. Therefore, in this study, structural modeling and dynamic analysis are performed to reflect the ground state and structural form of Cheomseongdae. Also, discrete element analysis technique is applied and dynamic behavior characteristics are analyzed according to earthquake load. For this purpose, displacements and stresses according to locations are reviewed and then swelling and distortion are analyzed.

In this paper, nitrogen-doped reduced graphene oxide(rGO) is obtained by thermal annealing of nitrogen-containing compounds and graphene oxide (GO) manufactured by modified Hummers' method. We use melamine as a nitrogen-containing compound and treat GO thermally with melamine at over 800 ~ 1,000℃ and 1 ~ 3 hr under Ar atmosphere. The electrical conductivity of doped rGO is measured by 4-point probe method. As a result, nitrogen contents on rGO are found to be in the range of 2.5 to 12.5 at% depending on the doping conditions after thermal annealing. The main doping site on graphene oxide is changed from pyridinic-N and pyrrolinic N to the graphitic site as the heat treatment temperature increases. The electrical conductivity of doped rGO increases as the N doping content increases. As the thermal treatment time increases, the change of both total doping contents and doping sites is slight and the surface resistance is remarkably reduced, which is caused by healing effects of doped graphene oxide at high temperature.

We performed seismic noise level analysis to access the proper functioning of 11 newly established seismic stations in the southeastern region of Korea. One-hour long segments of seismograms were selected from the continuous data of the 3 elements for 61 days from March 1, 2019. For each segment of data, the power spectral density (PSD) was estimated from the continuous back ground noise data of the 3 elements for periods ranging from 0.02~100 s. The median noise levels (NLs) of the stations were compared with the new noise model (NNM) of USGS and NLs of station TJN installed in a tunnel on a granite basement. We observed that the NLs of the newly installed seismometers were between the upper and lower limit of the NNM. In a comparison with the noise level of station TJN, the new seismometers had their own noteworthy features. The NLs from accelerometers (Epi-sensors) were ~ 40 dB higher than the NLs from velocimeters (STS-sensors) for periods > 10 s, which is because the small and light Epi-sensors are sensitive to environmental changes. Daily and weekly variations in spectral noise level were observed clearly in short periods < 1 s, and these are considered to be related to human activities. The seismometers in boreholes showed ~20 dB weaker NLs in the cultural noise band. The NLs of accelerometers at a depth of 30 m were also much lower by 30 dB for long periods > 10 sec. Overall the functioning of the new velocimeter and accelerometer stations was reliable for periods ranging from 0.02~100 s and 0.02~10 s, respectively.

When a train enters a tunnel, a pressure wave is generated. This pressure wave propagates in the tunnel and emits as micro pressure wave at the opposite tunnel exit. This pressure wave could appear as a sound pulse in a particular environment and cause hazardous effects on the environment near the tunnel exit. When planning tunnels, it is necessary to take appropriate measures to reduce the magnitude of the micro pressure wave. In this study, we investigated the existing micro pressure wave management standards and studied the signal processing method and the sound evaluation method which were used in setting the appropriate management standard for the evaluation of the micro pressure wave.

Ink-jet printing is a manufacturing process technology that directly prints a digitalized design pattern onto a substrate using a fine ink jetting system. In this study, environmentally friendly yellow aqueous ceramic ink is synthesized by mixture of distilled water, yellow ceramic pigment and additives for ink-jet printing. The graft polymer, which combines electrostatic repulsion and steric hindrance mechanism, is used as a surfactant for dispersion stability of aqueous ceramic ink. Synthesized ceramic ink with graft polymer surfactant shows better dispersion stability than did ceramic ink with PAA surfactant; synthesized ink also shows desirable ink-jet printability with the formation of a single ink droplet during printability test. Finally, ceramic ink printed on glass substrate and ceramic ink with graft polymer surfactant shows a high contact angle without surface treatment on glass substrate. Consequently, it is confirmed that the ceramic ink with graft polymer surfactant can achieve high printing resolution without additional surface treatment process.

This study compares and analyzes inorganic components of four different Pu-erh tea species consumed in Korea. The criteria for the inorganic components was based on the Royal Institute of Technology (KTH) recommendations. Out of the 19 general items: potassium, manganese, silicon and fluorine were detected in amounts exceeding the maximum allowable concentration by 5~23, 57~91, 1.6~1.8 and 9~18 times respectively. Out of the 15 potentially harmful elements: aluminum and nickel were exceeded the Maximum allowable concentration by 9~14 times and 0.8~1.2 times respectively. To reduce the concentration of inorganic elements in excess of the maximum allowable concentration, the extraction time of tea should be less than 1 minute in addition to limiting the amount. The amount of Pu-erh tea for extraction was about 0.1 g manganese, about 0.3 g potassium, about 0.5 g fluoride and about 2 g silicon. Therefore, the maximum amount of tea for extraction should be 0.1 g in regards to the safety of Pu-erh tea. Based on the recommended maximum daily intake of inorganic ingredients by the Ministry of Food and Drug Safety, it is desirable that the number of extractions be less than three.

Information and communication technologies are developing rapidly as IC chip size becomes smaller and information processing becomes faster. With this development, digital circuit technology is being widely applied to mobile phones, wireless LANs, mobile terminals, and digital communications, in which high frequency range of GHz is used. In highdensity electronic circuits, issues of noise and EMC(Electro-Magnetic Compatibility) arising from cross talk between interconnects or devices should be solved. In this study, sheet-type electromagnetic wave absorbers that cause electromagnetic wave attenuation are fabricated using composites based on soft magnetic metal powder and silicon rubber to solve the problem of electromagnetic waves generated in wireless communication products operating at the frequency range of 2.4 GHz. Sendust(Fe-Si-Al) and carbonyl iron(Fe-C) were used as soft magnetic metals, and their concentrations and sheet thicknesses were varied. Using soft magnetic metal powder, a sheet is fabricated to exhibit maximum electromagnetic attenuation in the target frequency band, and a value of 34.2dB(99.9 % absorption) is achieved at the target frequency.

열대몬순기후인 캄보디아에서 2011년부터 2013년까지 건기와 우기로 구분하여 사료용 옥수수인 국내 품종인 광평옥과 평안옥 그리고 수입 품종인 CP888과 Loeung Mongkul에 대한 생육과 수량특성을 구명한 결과이다. 출사 소요일수는 건기 재배에 있어서 2011과 2012년 및 2013년에는 큰 차이가 나타나지 않았으나, 우기 재배에서는 2012년이 2011년에 비해 6일이 단축되었으며 품종간 약 2-3 일의 차이를 보였다. 종실 수량은 건기 재배에서 2012년(548-788 kg/10a)이 2011 년(386-505 kg/10a)과 2013년(345-687 kg/10a)에 비해 다소 높았다. 우기 재배에서는 2012년(369-582 kg/10a)과 2011년(221-601 kg/10a)간에 차이를 보이지 않았다. 그러나 품종간 유의한 차이를 보였다. 본 연구결과 우기 재배에서 안정적인 옥수수 수량을 확보하려면 강수량이 높은 8월과 9월 및 10월 보다는 우기 전인 6월과 7월에 파종하는 것이 좋으며, 건기 재배에서는 충분한 관개가 있는 조건에서 12월부터 다음 년도인 2월 말까지가 파 종하는 것이 최대 수량을 확보하는데 유리할 것으로 사료된다.