This study aims at an acoustic design of the classical concert hall and evaluation of the acoustic performance. In terms of three acoustic parameters (i.e., reverberation time (RT), clarity (C80), and lateral fraction (LF)), this study performed acoustic simulation modeling and site measurement with the K Art Hall located in South Korea as a case study. First, in order to meet the acoustic performance of the K Art Hall (target RT: 1.4~1.7 seconds, target C80: -2dB or more +2dB or less, and target LF: 10~35%), the finish materials and shape of the room as an interior acoustic design were determined. Second, the average values of the RT, C80, and LF using the acoustic simulation modeling were estimated at 1.4 second, 1.2~1.6 dB, and 29%, respectively. Third, the average values of the RT, C80, and LF through site measuring were measured at 1.5~1.64 second, 0.07~1.31dB, and 22.22~31.37%, respectively. Thus, the results of both the acoustic simulation modeling and site measuring were analyzed so as to satisfy the target acoustic performance. The results of this study will help the decision-makers (i.e., owner, construction managers, etc.) to plan the classical concert hall in terms of the RT, C80, and LF.

Ensuring a protection scheme in DC distribution is more difficult to achieve against pole-to-ground fault than in AC distribution system because of the absence of zero crossing points and low line impedance. To complement the major obstacle of limiting the fault current, several compositions have been proposed related to mechanical switching and solid-state switching. Among them, solid-state circuit breakers(SSCBs) are considered a possible solution to limit fast fault current. However, they may cause problems in circuit complexity, reliability and cost-related troubles due to the use of multiple power semiconductor devices and additional circuit configuration to commutate current. This paper proposes the SSCB with a coupled inductor(SSCB-CI) which has symmetrical configuration. The circuit is comprised of passive components like commutation capacitors, a CI and damping resistors. Thus, proposed SSCB-CI offers the advantages of simple circuit configuration and fewer utilized power semiconductor devices than another typical SSCBs in LVDC microgrid. For analysis, six operation states are described for the voltage across main switches and fault current. The effectiveness of the SSCB-CI against a short-circuit fault is proved via simulation and experimental results in a lab-scale prototype.

Though melatonin is known to improve ultraviolet B (UVB)-induced oxidative damage and inflammatory conditions via blockade of nuclear factor (NF)-κB, interleukin (IL)-6, there is no report on anti-wrinkle effect of melatonin to date. Hence in the present study, anti-wrinkle mechanism of melatonin was elucidated in UVB treated HaCaT keratinocytes and hairless mice. Herein melatonin protected against a radical initiator tert-Butyl hydroperoxide (t-BOOH) induced reactive oxygen species (ROS) production, matrix metalloprotease 1 (MMP-1) and cytotoxicity in HaCaT keratinocytes. Also, melatonin suppressed the expression of sonic hedgehog (SHH) and GLI for hedgehog signaling, p-NF-kB, cyclooxygenase (COX-2), p-ERK for inflammatory responses in UVB treated HaCaT keratinocytes. Furthermore, melatonin protected skin from wrinkle formation, transdermal water loss in hairless mice irradiated by UVB for 8 weeks. Notably, melatonin prevented against epidermal thickness and dermal collagen degradation in UVB irradiated hairless mice by Hematoxylin & Eosin and Masson’s trichrome staining. Taken together, these findings suggest that melatonin reduces wrinkle formation via inhibition of ROS/SHH and inflammatory proteins such as NF-kB/COX-2/ERK/MMP1.