Delayed onset muscle soreness (DOMS) is a painful condition that arises from e+M8xercise-induced muscle damage after unaccustomed physical activities. Various therapeutic interventions have been applied to reduce the intensity and duration of DOMS-related symptoms. Recently, pulsed electromagnetic field (PEMF) intervention has been introduced as an alternative noninvasive treatment for DOMS. This randomized, double-blind, placebo-controlled experiment was conducted to examine the effects of PEMF therapy on DOMS in elbow flexors at 24, 48, and 72 hours after the experimental DOMS induction. Thirty healthy volunteers ( yrs, cm, and kg) participated in this study. Each was randomly assigned to a PEMF or placebo group. On the first day, DOMS was induced in the elbow flexors by repeated isokinetic motions at low () and fast () speeds in all subjects. Thereafter, the PEMF group received 15-min daily treatment with a PEMF device. The placebo group received sham treatment of the same duration. Overall, PEMF application was more effective than the sham treatment in reducing the physiological symptoms associated with the DOMS including perceived soreness, median frequency, and electromechanical delay of the surface electromyography. In addition, median frequency and isokinetic peak torque of the PEMF group recovered to the pre-DOMS induction level earlier than the placebo group. In conclusion, this study suggests that PEMF can be applied as a new recovery strategy in reducing DOMS symptoms. Further experiments are required to examine the effect of the PEMF treatment on different types of exercise conditions and to determine the optimal treatment dosage and duration in a real clinical setting.

전기추진선박의 추진시스템에 주로 사용되는 3상 정류기의 입력전류는 다양한 저차 고조파를 포함하고 있다. 이러한 고조파 저감을 위해서 대전력이 필요한 대형 선박에 사용되는 전력변환장치는 12펄스 출력의 정류기가 현재 사용되고 있지만 여전히 12±1차의 고조파가 발생되는 문제점이 있다. 또한, 속도 및 토크 제어기법으로 널리 사용되고 있는 직접토크제어기법의 경우에는 토크 리플이 심하고 전동기의 입력전류는 인버터의 스위칭에 의해 고조파를 크게 포함하고 있다. 본 연구에서는 직접토크제어기법을 이용하는 전기추진시스템의 12펄스 정류기에 보조 전원을 공급하여 고조파를 저감하고 토크 제어성능을 향상시켰으며 실선시스템 환경에서 시뮬레이션을 통해 그 유효성을 입증하였다.

The Cu2ZnSnS4 (CZTS) thin film solar cell is a candidate next generation thin film solar cell. For the application of an absorption layer in solar cells, CZTS thin films were deposited by pulsed laser deposition (PLD) at substrate temperature of 300˚C without post annealing process. Deposition time was carefully adjusted as the main experimental variable. Regardless of deposition time, single phase CZTS thin films are obtained with no existence of secondary phases. Irregularly-shaped grains are densely formed on the surface of CZTS thin films. With increasing deposition time, the grain size increases and the thickness of the CZTS thin films increases from 0.16 to 1μm. The variation of the surface morphology and thickness of the CZTS thin films depends on the deposition time. The stoichiometry of all CZTS thin films shows a Cu-rich and S-poor state. Sn content gradually increases as deposition time increases. Secondary ion mass spectrometry was carried out to evaluate the elemental depth distribution in CZTS thin films. The optimal deposition time to grow CZTS thin films is 150 min. In this study, we show the effect of deposition time on the structural properties of CZTS thin film deposited on soda lime glass (SLG) substrate using PLD. We present a comprehensive evaluation of CZTS thin films.

대표적인 2종의 미생물(E. coli, B. subtilis)을 이용하여 초기 미생물 농도에 대한 광 펄스의 영향을 살펴본 결과, 미생물의 사멸율이 초기 농도에 영향을 받지 않았고 25 kV에서 1500 μs 처리 시 최소 5 log 이상의 미생물 감소를 보인다는 것을 확인할 수 있었다. 그리고 4종의 유해미생물(B. subtilis, E. coli, S. aureus, S. typhimurium)의 광 펄스 처리시간에 따른 미생물 사멸효과는 모든 미생물이 처리시간에 증가함에 따라 효과가 상승하였고 1500 μs 처리 시 모든 미생물이 6 log 이상의 감소를 보였다. 또한 광 펄스 처리시간에 따른 미생물 사멸속도는 1차 반응속도와 상응함을 알 수 있었다. 그리고 4종 유해미생물의 배지 두께에 따라 미생물 불활성화 효과에 대한 민감 정도를 알아본 결과 E. coli의 두께 민감 상수가 4.9로 가장 높게 나타났으며 이는 시료의 두께가 증가함에 따라 미생물 사멸효과가 감소하는 것을 알 수 있었다. 마지막으로 여러 가지 색(노랑, 빨강, 파랑, 녹색, 흑색)에 따른 E. coli의 사멸 효과는 유의적인 차이가 없는 것으로 나타났다. 결과적으로 초기 균체농도, 광 펄스 처리 시간, 두께에 따른 미생물 사멸효과의 민감도 등이 실제 식품 적용하기 위한 기초 자료로 활용할 수 있을 것으로 사료된다.

Sintered bulks of nanopowders were fabricated by magnetic pulsed compaction (MPC) and subsequent two-step sintering employed in this study and the formability effects of nanopowder on mixing condition, pressure and sintering temperature were investigated. The addition of PVA induced and increase in the formability of the sintered bulk. But cracked bulks were obtained on sintering with addition of over 10 wt% PVA due to generation of crack during sintering. The optimum compaction pressure during MPC was 1.0 GPa and mixing conditions included using 5.0 wt% PVA. The optimum processing condition included MPC process, followed by two-step sintering (first at 1000 and then at ). The sintered bulks with the diameter of 30 mm under these conditions were found to have non crack, ~99% density.

Intense pulsed light(IPL) has been highlighted as an innovative nonthermal sterilization technology that can kill spoilage or pathogenic microorganisms by using short-duration pulses of intense broad-spectrum electromagnetic radiation. This paper examines the inactivation effects of IPL on Listeria monocytogenes, Escherichia coli O157:H7, and Pseudomonas aeruginosa inoculated on seafood products such as salmon, flatfish, and shrimps and evaluates the possibility of extending the shelf-life of seafood products. The results indicate that the inactivation of microorganisms increased with an increase in IPL energy density(J/㎠) and a decrease in the distance between the sample surface and the lamp. In addition, temperature increases on the fish fillets during the treatments were well controlled within the range of 5.7～9.8℃. The IPL treatment had a significant positive effect on the storage stability of seafood products at the storage temperature of 4℃ for 12 days. These results suggest that the storage period for fish fillets can be extended from 4 days to 6～8 days through the IPL treatment.

In this study, we reported the microstructure and properties of Ag- contact materials fabricated by a controlled milling process with subsequent consolidation. The milled powders were consolidated to bulk samples using a magnetic pulsed compaction process. The nano-scale phases were distributed homogeneously in the Ag matrix after the consolidation. The relative density and hardness of the Ag- contact materials were 95~96% and 89~131 Hv, respectively.

Nanostuctured TiAl powder was synthesized by high energy ball milling. A dense nanostuctured TiAl was consolidated using pulsed current activated sintering method within 2 minutes from mechanically synthesized powders of TiAl and horizontally milled powders of Ti+Al. The grain size and hardness of TiAl sintered from horizontally milled Ti+Al powders and high energy ball milled TiAl powder were 35 nm, 20 nm and 450 kg/, 630 kg/, respectively.

This article presents the successful consolidation of the mixed Co and Diamond powders for a drilling segment by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were analyzed. Homogeneous hardness (Hv 220) and density (97%) of sintered bulks fabricated by MPC were obtained by the new technique, where higher pressure has been employed for short period of time than that of general process. A fine microstructure and homogeneous hardness in the consolidated bulk were observed without cracks. Relatively higher drilling speed of 9.61 cm/min and life time of 6.55 m were found to the MPCed specimens, whereas the value of the specimens fabricated by general process was 11.71 cm/min and 7.96 m, respectively. A substantial improvement of mechanical properties of segment was achieved through this study.

In this research, fine-structure TiO2 bulks were fabricated in a combined application of magnetic pulsed compaction (MPC) and subsequent sintering and their densification behavior was investigated. The obtained density of TiO2 bulk prepared via the combined processes increased as the MPC pressure increased from 0.3 to 0.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7 GPa was attributed to the decrease of the inter-particle distance of the pre-compacted component. High pressure and rapid compaction using magnetic pulsed compaction reduced the shrinkage rate (about 10% in this case) of the sintered bulks compared to general processing (about 20%). The mixing conditions of PVA, water, and TiO2 nano powder for the compaction of TiO2 nano powder did not affect the density and shrinkage of the sintered bulks due to the high pressure of the MPC.

This article presents the challenges toward the successful consolidation of nanopowder using magnetic pulsed compaction (MPC). In this research the ultrafine-structured bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their properties were investigated. The obtained density of bulk prepared by the combined processes was increased with increasing MPC pressure from 0.5 to 1.25 GPa. Relatively higher hardness and fracture toughness in the MPCed specimen at 1.25 GPa were attributed to the retention of the nanostructure in the consolidated bulk without cracks. The higher fracture toughness could be attributed to the crack deflection by homogeneous distribution and the retention of nanostructure, regardless of the presence of porosities. In addition, the as consolidated bulk using magnetic pulsed compaction showed enhanced breakdown voltage.

Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.