http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
New methodology to concentrate fossil pollen for radiocarbon dating and stable isotope analyses
Jungjae Park 국토지리학회 2004 국토지리학회지 Vol.38 No.1
Since Brown et al. (1989) first reported the direct dating of fossil pollen concentrates by AMS, many researchers have made efforts to obtain an enough amount of fossil pollen from sediments for the AMS radiocarbon dating. Visually sorting a large number of pollen grains is however very difficult and time consuming. I found that by the use of flow cytometry it is possible to concentrate a substantial amount of pollen from sediments within a short time. Another advantage of cytometric sorting is that it minimizes the necessity for chemical treatments, which may shift the isotopic ratios of pollen. The research results indicate that high resolution of paleo records can be constructed comparing between isotopic ratios of modern pollen samples and fossil pollen samples. The use of fossil pollen concentrates sorted by the flow cytometer for the AMS radiocarbon dating and isotopic analyses will help revealing the past climate change.
A review of thickness measurements of thick transparent layers using optical interferometry
Jungjae Park,김종안,Heulbi Ahn,Jaeseok Bae,진종한 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.3
Thickness is a typical parameter related to length, of which measurements are conducted in various industrial fields, such as the automotive, aviation, ship-building, semiconductor, and display industries. Among various measurement techniques, optical interferometry is very attractive in terms of reliability owing to the direct realization of the metre. Moreover, the nature of this non-contact method is such that it does not damage samples. In this review, optical interferometric methods for measuring thicknesses of thick transparent layers are introduced through a discussion of basic principles and applications. With consideration of optical layouts and analysis methods of interference signals, monochromatic laser interferometry, low-coherence interferometry, and spectral interferometry are introduced and discussed in chapters 2, 3 and 4, respectively. With regard to spectral interferometry, the two different key technologies of spectrally resolved interferometry and wavelength-scanning interferometry are covered in different subsections of chapter 4.
Vibration-desensitized interferometer by continuous phase shifting with high-speed fringe capturing.
Park, Jungjae,Kim, Seung-Woo Optical Society of America 2010 Optics letters Vol.35 No.1
<P>Optical interferometers for surface metrology require high immunity to vibration when they are to be used outside the laboratory environment. Here we describe a continuous phase-shifting method as a means of vibration suppression, which implements phase shifting uninterruptedly while capturing resulting interference fringes at a high rate. The continuous phase shifting allows the interference initial phase under measurement to be locked to a single temporal frequency in captured fringes, thereby being recovered free from vibration by Fourier-based postprocessing. This continuous phase-shifting method can be realized with any phase-shifting interferometers by incorporating a high-speed digital camera with good intensity-to-voltage conversion linearity.</P>
Park, Jungjae,Chen, Lingfeng,Wang, Quandou,Griesmann, Ulf Optical Society of America 2012 Optics express Vol.20 No.18
<P>We describe a method to simultaneously measure thickness variation and refractive index homogeneity of 300 mm diameter silicon wafers using a wavelength-shifting Fizeau interferometer operating at 1550 nm. Only three measurements are required, corresponding to three different cavity configurations. A customized phase shifting algorithm is used to suppress several high order harmonics and minimize intensity sampling errors. The new method was tested with both silicon and fused silica wafers and measurement results proved to be highly repeatable. The reliability of the method was further verified by comparing the measured thickness variation of a 150 mm diameter wafer to a measurement of the wafer flatness after bonding the wafer to an optical flat.</P>
Biogeographical Studies in Korea
Jungjae Park 대한지리학회 2012 대한지리학회지 Vol.47 No.4
본 논문에서는 지금까지의 국내 생물지리학 연구를 세 분야로 구분하여 검토하였다: 1) 환경 인자와 식물 분포 간 관계, 2) 과거 식생과 기후, 3) 인간과 환경 간 상호작용. 과거 한국(국내) 지리학계에서 생물지리학은 중시되지 않았다. 이로 인해 현재 저변은 매우 얕은 실정이다. 그러나 생물지리학의 향후 전망은 나쁘지 않으며 앞으로 더욱 발전할 수 있는 가능성을 내재하고 있다. 국내에서 생물지리학을 점진적으로 꾸준하게 발전시키기 위해서는 보다 많은 학생들을 생물지리학 분야로 유도하는 것이 중요하다. In this paper, three general academic issues in Korean biogeographical studies were comprehensively reviewed: 1) relationship between environmental factors and plant distribution, 2) past vegetation and climate 3) interaction between humans and environment. Biogeography in Korea is poorly developed field and has been generally ignored by geographers in Korea. The future for biogeography in Korea however seems promising and Korean biogeographers have a great opportunity to develop their field. To attract more prospective graduate students into biogeography and train them would be very important for the gradual and persistent development of geographical biogeography in Korea.
Park, Jungjae,Byrne, Roger,Bö,hnel, Harald Elsevier 2017 Earth and planetary science letters Vol.464 No.-
<P><B>Abstract</B></P> <P>Periodic droughts have been one of the most serious environmental issues in central Mexico since the earliest times. The impacts of future droughts are likely to become even more severe as the current global warming trend increases potential evaporation and moisture deficits. A full understanding of the mechanism underlying climate variability is imperative to narrow the uncertainty about future droughts and predict water availability. The climatic complexity generated by the combined influence of both Atlantic and Pacific forcings, however, causes considerable difficulty in interpreting central Mexican climate records. Also, the lack of high-resolution information regarding the climate in the recent past makes it difficult to clearly understand current drought mechanisms. Our new high-resolution <SUP> δ 18 </SUP> O record from Hoya Rincon de Parangueo in central Mexico provides useful information on climate variations since the early 1600s. According to our results, the central Mexican climate has been predominantly controlled by the combined influence of the 20-year Pacific Decadal Oscillation (PDO) and the 70-year Atlantic Multidecadal Oscillation (AMO). However, the AMO probably lost much of its influence in central Mexico in the early 20th century and the PDO has mostly driven climate change since. Marked dryness was mostly associated with co-occurrence of highly positive PDO and negative AMO between ∼1600 and 1900.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New high-resolution sedimentary <SUP> δ 18 </SUP> O data from central Mexico since the early 1600s. </LI> <LI> Combined influence of the 20-year PDO and the 70-year AMO on central Mexico. </LI> <LI> Co-occurrence of highly positive PDO and negative AMO was linked to marked dryness. </LI> <LI> The climate mechanism suggested here would be useful to improve drought prediction. </LI> </UL> </P>
Park, Jungjae,Bae, Jaeseok,Kim, Jong-Ahn,Jin, Jonghan North-Holland 2019 Optics communications Vol.431 No.-
<P><B>Abstract</B></P> <P>A non-destructive method for measuring the physical thickness and group refractive index of individual layers was proposed based on spectral-domain interferometry, which was realized to achieve real-time measurements using a mode-locked laser and an optical spectrum analyzer. As a double-stacked specimen, a microfluidic channel mold composed of a SU-8 photoresist and a silicon wafer was chosen. With areal scanning of the sample, a physical thickness map and a representative group refractive index value for each layer were obtained at the same time. The sample was measured 30 times consecutively at pre-determined points to estimate the repeatability of the physical thickness, for which the standard deviation was less than 10 nm. Moreover, a measurement comparison with two calibrated reference instruments was conducted. According to the comparative measurement results, physical thickness values obtained by the proposed method and with each comparative method were found to be in good agreement within expanded uncertainty levels.</P>