The 2017 Pohang earthquake afflicted more significant economic losses than the 2016 Gyeongju earthquake, even if these earthquakes had a similar moment magnitude. This phenomenon could be due to local site conditions that amplify ground motions. Local site effects could be estimated from methods using the horizontal-to-vertical spectral ratio, standard spectral ratio, and the generalized inversion technique. Since the generalized inversion method could estimate the site effect effectively, this study modeled the site effects in the Korean peninsula using the generalized inversion technique and the Fourier amplitude spectrum of ground motions. To validate the method, the site effects estimated for seismic stations were tested using recorded ground motions, and a ground motion prediction equation was developed without considering site effects.

This study simulated strong ground motion waveforms in the southern Korean Peninsula, based on the physical earthquake modeling of the Southern California Earthquake Center (SCEC) BroadBand Platform (BBP). Characteristics of intensity attenuation were investigated for M 6.0-7.0 events, incorporating the site effects. The SCEC BBP is software generates broadband (0-10 Hz) ground-motion waveforms for earthquake scenarios. Among five available modeling methods in the v16.5 platform, we used the Song Model. Approximately 50 earthquake scenarios each were simulated for M 6.0, 6.5, and 7.0 events. Representative metrics such as peak ground acceleration (PGA) and peak ground velocity (PGV) were obtained from the synthetic waveforms that were simulated before and after the consideration of site effects (VS30). They were then empirically converted to distribution of instrumental intensity. The intensity that considers the site effects is amplified at low rather than high VS30 zones.

한반도 남동부에서 관측된 지진기록을 이용하여 스펙트럼 감쇠상수 \chi와 응력강하상수를 계산하였다. 특히, 스펙트럼 감쇠상수 \chi는 관측소별로 부지고유의 특성을 반영하여 새로운 방법으로 계산하였다. 이 방법은 2단계의 계산과정으로 구성된다. 첫 번째 단계에서는 코다(coda)파 정규화법을 이용하여 광역적 상수인 비탄성감쇠 Q를 역산하고, 이로부터 스펙트럼의 거리종속적인 감쇠효과를 일으키는 \chi_{q}값을 계산한다. 두 번째 단계에서는 앞서 계산된 \chi_{q}값을 관측소별로 동일하게 적용하여 거리와 무관한 스펙트럼 감쇠효과인 부지고유의 \chi_{s}값을 추정한다. 관측소에 관계없이 평균적으로 계산된 \chi값의 진원거리(R)에 따른 경향은 0.016+0.000157R이다. 응력강하상수는 1999년 경주근방에서 세 차례 발생한 지진의 관측자료를 이용하여 조남대와 박창업 방법으로 계산하였으며, 그 결과는 92-bar이다. 이들 상수를 이용하여 추계학적 모사법으로 한반도 남동부에서 발생 가능한 강지진동의 최대지반운동과 주파수에 따른 특성을 간접적으로 추정하였다. 이러한 추계학적 모사의 결과를 바탕으로 진원거리에 따른 지진동 감쇠공식을 유도하였으며 기존의 국내연구와 비교, 분석하였다.하였다

This study was designed to analyze the chemical composition of essential oil in ‘Shiranuhi’ immature fruitand to test their biological activities. ‘Shiranuhi’ immature essential oils (SIEO) were obtained by steam distillation fromfruits collected from Jeju Island and were analyzed using gas chromatograph (GC)-flame ionization detectors (FID) andGC-MS. Fourteen components were identified in the essential oil. Limonene (75.21%) and terpineol (8.68%) were the majorcomponents in SIEO. Since acne vulgaris is the combined result of a bacterial infection and the inflammatory response tothat infection, we examined whether SIEO possessed antibacterial against skin pathogens. As a result, SIEO showed excel-lent antibacterial activities against drug-susceptible and -resistant Propionibacterium acnes and Staphylococcus epidermidis,which are acne-causing bacteria. In this study, SIEO was examined on DPPH radical scavenging activities, which showedmoderate antioxidant activity (SC50, 15.36µL/mL). In order to determined whether SIEO can be safely applied to humanskin, the cytotoxicity effects of SIEO were determined by colorimetric MTT assays in normal human fibroblasts and kerati-nocyte HaCaT cells. They exhibited low cytotoxicity at 0.5µL/mL in both celllines. Based on these results, we suggest thepossibility that essential oil of ‘Shiranuhi’ maybe considered as an antibacterial and antioxidant agent.

The purpose of this study is to consider site effect in order to estimate Soil-Structure and attenuation parameters with a greater degree of reliability. Site amplification is calculated by proposed Nakamura (H/V ratio). The site amplifications using acceleration motion were compared at several sites. The result can be used for the study of site classification and removal of the site amplification effects.