A new species of chionelasmatid sessile vent barnacle, Eochionelasmus coreana sp. nov., is described and illustrated on the basis of specimens collected from the Solitaire hydrothermal vent field in the Central Indian Ridge of the Indian Ocean. This new species is morphologically very similar to E. ohtai, the type species of the genus Eochionelasmus. However, it differs from E. ohtai in its distribution, the status of the notch on the maxillule, and the positions of rl1 and cl1 on whorls of the imbricating plates. In addition, a molecular phylogenetic tree indicated that the chionelasmatid Eochionelasmus was closely related to the waikalasmatid Waikalasma with high supporting values rather than the other chionelasmatid Chionelasmus. The new species is not only the first record of a sessile vent barnacle from outside of the Pacific Ocean, but is also the first sessile barnacle from the Indian Ocean.

Stable carbon isotope ratios were measured on the alpha-cellulose in tree rings of a pine tree (Pinus densiflora) from Yeongwol, Korea. We developed an annual-resolution δ13C series (1835–1905) by correcting the measured data for changes in δ13C of air to minimize non-climatic influences. To investigate the climatic signal in the δ13C series, we performed correlation analysis between δ13C and the Cheugugi climate data. The Cheugugi precipitation data were first recorded by King Sejong (1397–1450) of the Joseon Dynasty. However, the longest set of precipitation data available is the one collected in Seoul (1776–1907). Although many studies support the reliability of the Cheugugi data, no previous studies have investigated the potential of the δ13C signal in tree rings as paleoclimate proxy using the Cheugugi data. Recent precipitation trends in Yeongwol are quite similar to that of Seoul, and we found significant correlations between the Cheugugi data and the δ13C series. We suggest further studies to replicate these results and confirm whether comparing δ13C variations in tree rings and Cheugugi data is a useful method of investigating the potential of the δ13C signal as a paleoclimate proxy in or near the Korean peninsula.

The lower dielectric constant (k) insulator is required for faster, smaller, and higher performance integrated circuit of the microprocessor and other advanced semiconductor devices that are so important to modern electronics and information technologies. Aromatic polyimides are among the candidate materials of low k due to their high thermal stability, mechanical strength and chemical resistance.

In this work, we show an 2,6-di-tert-butyl-9,10-diphenylanthracene core based novel polyimide which has been designed to have the lower polar imide concentration compared to that of conventional polyimides as well as the synthesis and characterization of its constitutional units, diamine and dianhydride.

At the Seoul National University accelerator mass spectrometry (AMS) laboratory, we are planning to develop an automated sample preparation system for higher throughput of radiocarbon dating. This system will consist of several sections, including a combustion line, CO2 trap, graphitization system, and so on. We usually collect CO2 by cryogenic trapping. However, since handling liquid nitrogen is expected to be rather difficult, we are interested in replacing the cryogenic method with the molecular sieve method for the collection of CO2. In this study, we compare the performance of the cryogenic trapping method and molecular sieve method. Zeolite 13X is used as a molecular sieve, and as test samples we use the oxalic acid standard (NIST SRM 4990C), high-purity graphite powder, and archaeological charcoals. The pMC values and the radiocarbon ages (BP) obtained from samples prepared by the above 2 methods are very similar. We especially focused on the memory effect of the molecular sieve, meaning the CO2 contamination from a previous sample, which can cause errors in age determination. To reduce this effect, we flowed He gas through a zeolite container for several minutes at a high temperature before the CO2 was introduced. By the adding this step, we have obtained more reliable results.

In Korean Paleolithic archaeology, it is traditionally thought that the Late Paleolithic stone tool industries were in some way derived from the Shuidonggou site in northern China. The latter site has long been considered to be the type site of the eastern Asian Late Paleolithic blade technology. However, recent studies suggest that a number of Korean Late Paleolithic sites probably predate Shuidonggou, some by several thousands of years. Here, we present a series of accelerator mass spectrometry (AMS) dates recently analyzed by the AMS laboratory at Seoul National University and discuss further the possibility that the introduction of blade (and later microblade) technologies into Korea may have originated directly from Mongolia, Siberia, and possibly other areas of northeast China, rather than from Shuidonggou.

The Neolithic in Korea began around 10,000 BP and is the period when many substantial changes appear in the archaeological record. In particular, one of the important changes is from a subsistence strategy that relied primarily on hunted, fished, and collected food packages to a diet that by the beginning of the Bronze Age (∼3500 BP) saw intensive agriculture as the primary form of sustenance. This paper discusses current research on this topic, in addition to presenting a comprehensive list of raw accelerator mass spectrometry (AMS) data from Korean Neolithic sites, particularly data that only became available over the past several years.

We investigated the pressure dependence of the inductive coupled plasma (ICP) oxidation on the electrical characteristics of the thin oxide films. Activation energies and electron temperatures with different pressures were estimated. To demonstrate the pressure effect on the plasma oxide quality, simple N type metal-oxide-semiconductor (NMOS) transistors were fabricated and investigated in a few electrical properties. At higher pressure than 200mTorr, plasma oxide has a slightly higher on-current and a lower interfacial trap density. The on-current gain seems to be related to the field mobility increase and the lower defective interface to the electron temperature during oxidation.

The application of chronometric dating studies in Korean archaeology has lagged behind similar research in China and Japan. The focus of this article is to provide an update on the accelerator mass spectrometry (AMS) radiocarbon dates derived from Korean Paleolithic and Early Neolithic sites. One of the major highlights from recent AMS 14C studies in Korea is that blade (and microblade) technologies may have diffused directly from Siberia, rather than through northern China as originally thought. In addition, a Neolithic wooden boat has been discovered in Korea that is as old as, if not older than, similar discoveries from eastern China. More detailed archaeological and chronometric studies in Korea in the coming years will certainly clarify many of the points mentioned here. In particular, through more detailed studies, we will be able to further evaluate the causal factors that provided the impetus for the Late Paleolithic-Neolithic transition in Korea.

We report radiocarbon dates for ∼150 archaeological sites in Korea belonging to the Neolithic-Bronze Age transition period. From the present compilation, we find that the Neolithic-Bronze Age transition in Korea started as early as ∼2300 BC and continued over the course of 800–900 yr with peaks representing population increases occurring 2–3 times. Compared with cases in other regions of the world, the Neolithic-Bronze Age transition in Korea was similar in both magnitude and transition time. However, the process in Korea appears to have occurred about 2000 yr later. Further, we find that the attempt to explain the Neolithic-Bronze Age transition in Korea as a migration hypothesis based only on a sudden population increase is not tenable.

Accelerator mass spectrometry (AMS) radiocarbon dates of pollen concentrate were obtained from multistage syngenetic ice wedges of cross-sections from the Late Pleistocene Bison site, located along the Lower Kolyma River (68°34'N, 158°34'E), from ∼43,600 to ∼26,200 BP, and 3 AMS 14C dates of pollen concentrate in ice wedges from the Seyaha site cross-section, located on the east coast of the Yamal Peninsula (70°10'N, 72°34'E), from ∼22,400 to ∼25,200 BP. Pollen concentrate samples were prepared using a special pretreatment procedure. Pollen and spores from ice-wedge ice signalize a regional pollen rain. Therefore, 14C-dated extracts of pollen and spores from ice-wedge ice enable an adequate reconstruction and chronology of landscape dynamics on a regional scale. The pollen and spores were well preserved despite numerous redepositions in the penecontemporaneous structure in which they were found. Thus, a comparison with dates on other fractions from the same sample is necessary. The youngest date is the most reliable among the intersample AMS 14C dates from the ice and permafrost sediments.

Under prolonged electron-beam exposure, perovskite-structured SrTiO3:Pr,Al,Ga (STO) phosphor can be easily reduced due to oxygen loss. In particular, it is well known that dissociative H2O molecules are well adsorbed on reduced STO surfaces. The hydroxyl species produced by such dissociative adsorption of H2O strongly decompose organic compounds chemisorbed on the surface from vacuum ambient used in display devices into carbon species due to the photocatalytic properties of STO. Consequently, it is very likely that this mechanism attributes to the larger amounts of carbon adsorption by electron-stimulated chemical reactions on the STO phosphor surface than other phosphors.

The evolution of the outer lake of Hwajinpo Lagoon in Korea has been reconstructed using environmental proxies (lithologic, geochemical, and fossil data) with a chronology established using 7 accelerator mass spectrometry (AMS) radiocarbon dates. Grain size, water content, and X-ray analyses from the core of outer coastal lakes (HJ99) were used to reconstruct sedimentary environments by using total organic carbon, C/N, S, and C/S chemical proxies. Assemblages of mollusc remains also provided paleoenvironmental information. The environmental changes of the outer lake of Hwajinpo Lagoon can be divided into 6 depositional phases. The basin of the Hwajinpo was exposed and underwent a weathering process before the Holocene period. The muddy sand layer on the weathered bedrock indicated an estuarine system about 6000 BP. The laminated layer implies that the lagoonal system was anoxic between about 5500–2800 BP. The marl layer implies a relatively oxic lagoonal condition with mollusc presence about 2500 B P. The layer of very low sulfur content indicates a freshwater lake system isolated by a sand barrier about 1700 BP. Beginning about 1000 B P, the river system deposits progress progradation on the marl layer. Two erosional landforms could be related with a high standing sea level span during Holocene. These high-stands are dated at 5700 BP and 2200 BP and are supposed to have formed erosional landforms of about 1.6 amsl and 0.8 amsl, respectively. Environmental changes of the outer lake of Hwajinpo Lagoon are considered due mainly to the lake- and sea-level fluctuation during Holocene.

A nanoscale continuous coating of In2O3 on phosphors for low-voltage display applications is proposed in which the electrical conductivity of phosphor screen plays a major role. The effect of In2O3 coating by the sol-gel method on the cathodoluminescence (CL) of ZnGa2O4:Mn phosphors improves the intensity of low-voltage CL noticeably compared with that of In2O3 mixing. It is understood that electrically conductive channels are formed by a much smaller amount of In2O3 addition than that of In2O3 mixing. Especially, based on transmission electron microscopy analysis, the formation of uniform nanoscale continuous In2O3 layers on the phosphor surface was confirmed. Also, the structural and CL characterizations presented in this paper clearly demonstrate that the nanoscale encapsulation of In2O3 layers on phosphors served as protective layers retarding the CL degradation introduced by the low-energy electron irradiation, which is critically important for the development of low-voltage display applications.

The Duvanny Yar cross-section located in the Lower Kolyma River valley of Northern Yakutia (69°N, 158°E, height above the Kolyma River level 55 m), has been studied and dated in detail by radiocarbon. The sequence mainly consists of sandy loam sediments with large syngenetic ice wedges. Their width at the top is 1–3.5 m. Allochthonous organic material occurs in high content, concentrating as 0.5–0.7 m lenses. Shrub fragments, twigs, and mammoth bones are accumulated in peaty layers. Through interpolation based on a series of 14C dates, dating of the host sediments provides an approximate age for the ice wedges. The 14C dates of various types of organic material are sometimes very close, but not all in agreement. Therefore, the dates do not accurately show the age of the δ18O and δD plots. A new approach is developed to a 14C dating strategy of syncryogenic sediments with high admixture of allochthonous organic material. The main purpose of this study is to consider detection of inversions or disturbances in the syngenetic permafrost sediment at the Duvanny Yar cross-section by 14C date series. Direct accelerator mass spectrometry (AMS) dating of the ice confirmed the relatively young age of ice wedges.

We fabricated InAs self-assembled quantum dots (QDs) on strained layer using molecular beam epitaxy. The strained layer consisted of InAs/GaAs superlattice(SL) and GaAs barrier layer on (001) GaAs substrate. Through controlling thickness of the strained layer, we formed two-dimensional alignments of QDs on misfit dislocation arrays along <110> directions made by strained layer. The increase of the strained layer thickness resulted in a stronger alignment of QDs, which were observed by atomic force microscopy studies. The aligned QDs were confirmed to confine carriers well and have different size distributions by photoluminescence measurement.