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Light–matter interactions based on noble metal nanostructures have received continued attention for their tremendous potential for the discovery of basic science as well as their application in pra...

Diffraction is a fundamental phenomenon that reveals the wave nature of light. When a plane wave is transmitted or reflected from a grating or other periodic structures, diffracted light waves propagate at several angles that are specified by the period of the given structure. When the optical period is shorter than the wavelength, constructive interference of diffracted light rays from the subwavelength-scale grating forms a uniform plane wave. Many studies have shown that through the appropriate design of meta-atom geometry, metasurfaces can be used to control light properties. However, most semitransparent metasurfaces are designed to perform symmetric operation with regard to diffraction, meaning that light diffraction occurs identically for front- and back-side illumination. We propose a simple single-layer plasmonic metasurface that achieves asymmetric diffraction by optimizing the transmission phase from two types of nanoslits with I- and T-shaped structures. As the proposed structure is designed to have a different effective period for each observation side, it is either diffractive or nondiffractive depending on the direction of observation. The designed structure exhibits a diffraction angle of 54°, which can be further tuned by applying different period conditions. We expect the proposed asymmetric diffraction meta-grating to have great potential for the miniaturized optical diffraction control systems in the infrared band and compact optical diffraction filters for integrated optics.

A wavelength-selective tunable plasmonic absorber is required for various applications, such as thermal imaging sensors, active biosensors, and switching devices in integrated optics. Using Ge2Sb2Te5 (GST), which is a representative phase change material showing a large change in optical characteristics, we propose a tunable plasmonic absorber that consists of a metal nanoslit array patterned on a GST-inserted dielectric layer. Based on systematic optimization, the proposed structure achieved a nearly zero reflectance for both states of the inserted GST film with a very large resonance shift after the phase transition. Moreover, the resonance wavelength of the proposed absorber could be flexibly tuned within a broad near-infrared range by tuning the geometric conditions of the nanoslit array and the thicknesses of the dielectric–GST–dielectric multilayer.

Complexity of anthropogenic influences on coastal ecosystems necessitates use of an integrated assessment strategy for effective interpretation and subsequent management. In this study a multiple lines of evidence (LOE) approach for sediment assessment, that combined use of chemistry, toxicity, and benthic community structure in the sediment quality triad was used to assess spatiotemporal changes and potential risks of persistent toxic substances (PTSs) in sediments of Masan Bay highlighting "long-term changes" between 1998 and 2014. Specific target objectives encompassed sedimentary PTSs (PAHs, alkylphenols (APs), and styrene oligomers), potential aryl hydrocarbon receptor (AhR; H4IIE-luc assay)- and estrogen receptor (ER; MVLN assay)-mediated activities, and finally several ecological quality (EcoQ) indices of benthic community structure. Concentrations of target PTSs in Masan Bay sediments were generally less by half in 2014 compared to those measured in 1998. Second, AhR-mediated potencies in sediments also decreased during this time interval, whereas ER-mediated potencies increased (+3790%), indicating that there has been substantial ongoing, input of ER agonists over the past 16 years. Potency balance analysis revealed that only 3% and 22% of the AhR- and ER-mediated potencies could be explained by identified known chemicals, such as PAHs and APs, respectively. This result indicated that non-targeted AhR and ER agonists had a considerable presence in the sediments over time. Third, EcoQ indices tended to reflect PTSs contamination in the region. Finally, ratio-to-mean values obtained from the aforementioned three LOEs indicated that quality of sediments from the outer region of the bay had recovery more during the period of 16-years than did the inner region. Overall, the results showed that even with the progress supported by recent efforts from the Korean governmental pollution control, PTSs remain a threat to local ecosystem, especially in the inner region of Masan Bay.

While the coastal pollution of persistent toxic substances (PTSs) has been widely documented, information on offshore environments remains limited. Here, we investigated the spatial distribution and sources of PTSs in the offshore sediments (n = 34) of South Korea. Sediment samples collected from the Yellow Sea (n = 18), the South Sea (n = 10), and the East Sea (n = 6), in 2017–18 were analyzed for a total of 71 PTSs. Target compounds include 31 PCBs, 15 PAHs, 9 emerging PAHs (e-PAHs), 10 styrene oligomers (SOs), and 6 alkylphenols (APs). Sedimentary PCBs showed relatively low concentrations with no significant difference across the three seas (0.16–6.9 ng g−1 normalized organic carbon, OC). Low-chlorinated PCBs (tri- and tetra Cl-CBs) were predominant (mean: 77%), primarily indicating atmospheric inputs. PAHs widely accumulated in the three seas with low to moderate level (22–250 ng g−1 OC), and dominated by high molecular weight PAHs (4–6 rings). PMF analysis revealed coast-specific PAHs sources; i.e., originated from mainly coke production (77%) in the Yellow Sea, vehicle emissions (68%) in the South Sea, and fossil fuel combustion (49%) in the East Sea. SOs showed significant contamination than other PTSs, with elevated concentrations in the Yellow Sea (mean: 350 ng g−1 OC). APs showed a similar regional distribution to SOs, but concentrations were much lower (mean: 17 ng g−1 OC). SOs and APs seemed to be introduced from rivers and estuaries on the west coast of Korea, where industrial and municipal activities are concentrated, then might be transported to offshore through tide or currents. Overall, the novel data presented for various PTSs in offshore Korean sediments warrant the necessity of a long-term monitoring effort and urgent management practice to protect marine ecosystem.

A metasurface is a planar optical device that controls the phase, amplitude, and polarization of light through subwavelength-scale unit elements, called meta-atom. The tunability of plasmonic vortex lens (PVL) which generates surface plasmon polaritons (SPPs) carrying orbital angular momentum can be improved by using meta-atom. However, conventional PVLs exhibit nonuniform field profiles according to the incident polarization states owing to the spin-orbital interaction (SOI) effect observed during SPP excitation. This paper describes a method of compensating for SOI of PVL by using the geometric phase of distributed nanoslits in a gold film. By designing the orientation angles of slit pairs, the anti-phase of the SOI effect can be generated for compensatory effect. In addition, polarization-independent PVLs are designed by applying a detour phase based on the position of the slit pairs. PVLs for center-, off-center-, and multiple-focus cases are demonstrated and measured via a near-field scanning microscope.

We present a polarization-dependent prism array film for controlling the viewing angle distribution of liquid crystal (LC) display panels without loss of light efficiency. On a directional backlight unit, our polarization-dependent prism array film, made into a stacked bilayer with a well-aligned liquid crystalline reactive mesogen (RM) layer on the UV-imprinted prism structure, can continuously control the light refraction function of the prism array by electrically switching incident polarization states of a polarization-controlling layer prepared by a twisted nematic LC mode. The viewing angle control properties of the polarization-dependent prism array film are analyzed under different prism angle and refractive index conditions of the RM layer. A simple analytic model is also presented to describe the intermediate viewing angle distributions with continuously varying applied voltages and incident polarization states.

Seo, S.; Park, Y.G.; Park, J.H.; Jeon, C.; Shin, C.W., and Jeong, H.D., 2016. Internal Tides in the Southwestern East/Japan Sea from Observation and Simulation. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 557–561. Coconut Creek (Florida), ISSN 0749-0208. Energetic internal tides were observed near the continental slope of the southwestern East/Japan Sea. We investigated the energetics of the internal tides using two data sets of 25-hour-long hourly CTD and LADCP profiles and idealized numerical modeling. The energy level during spring tide was about five times stronger than that of neap. During both observation periods the semi-diurnal M2 constituent was dominant. Internal tide energy flux peaked at about 150 m level where the amplitude of the internal tide was largest. During spring tide the energy flux directed to the deeper part of...

A tunable plasmonic nanocavity which consists of a metallic groove with submerged ultra-thin Ge2Sb2Te5 film is proposed for controlling the on/off characteristics of directional surface plasmon polaritions (SPPs) launching. Different mechanisms of launching SPPs using two orthogonal incident polarizations are investigated to reveal the SPP generation characteristics from the proposed nanocavity. By choosing the appropriate position of Ge2Sb2Te5 film, we report that the directional launching characteristics of SPPs can be controlled by changing the phase state of extremely small volume of Ge2Sb2Te5 film, which shows up to 37 dB of extinction ratio changing characteristics.

We investigated the spatial and temporal variations of phytoplankton in Youngil Bay as well as the effect of water physico-chemical parameters. Water samples at three stations were collected and measured monthly from May to November in 2010. The taxa of phytoplankton observed in this study were classified as 33 Bacillariophyceae, 23 Dinophyceae, 1 Euglenophyceae, 2 Crysophyceae and 1 Cryptophyceae. The highest biomass of phytoplankton was observed at inner station in September, which was characterized high concentration of dissolved inorganic phosphate(DIP) in surface water after rainfall. Nutrient concentrations, chlorophyll-a and phytoplankton biomass values showed the marked trend to decrease from the inner bay to the outer bay. Pearson's correlation co-efficient between salinity and other water parameters including chlorophyll-a, pH and DIP showed the strong negative relationship r=-0.82, r=-0.78 and r=-0.75 (p ＜ 0.01), respectively. These results indicate that the water quality of Youngil Bay could be stimulated by nutrient enriched input from Hyeogsan River discharge, and the spatial and temporal distribution of phytoplankton biomass principally limited to DIP concentration from Hyeogsan river.

The dynamics (interannual) of dissolved inorganic nutrient concentrations (dissolved inorganic nitrogen, DIN; dissolved inorganic phosphorus, DIP; and dissolved inorganic silicate, DSi) were investigated in inshore and offshore waters of Korea using time series data collected from 1994 to 2010. During this period the DIN concentration progressively decreased in most parts of the inshore areas, but markedly increased in offshore waters. In the inshore waters, where river-borne nutrients are a dominant source, the trend of decreasing DIN concentration reflected the trends of riverine DIN. Riverine sources are less important in the offshore waters, and the trends of increasing concentrations of DIN and DSi in the offshore waters reflected the trends of increase in atmospheric deposition and Asian dust, respectively. Inputs from submarine groundwater discharge and lateral current transport were also partly responsible for the changes in nutrient concentrations in the inshore and offshore waters, respectively. Our results indicate that the recent changes in nutrient concentrations in the inshore and the offshore waters of Korea are largely governed by changes in the relative contributions from riverine inputs and atmospheric deposition, which often have differing trends over time.

In this study, we estimate the interannual spatial and temporal distributions of fishing grounds at night in the East Sea based on satellite and in-situ data. We observe that the thermal front moves in the north-south direction according to the movement of the warm water (above ) in the Tsushima Warm Current (TWC) area, forcing the cold water area (below ) to either expand or shrink. The interannual variations of sea surface temperature (SST) in winter represented by the indicator SST of are consistent with the east-west zonal areas in the central East Sea which represented over standard deviation of SST in February during 1990-2000. Annual SST in the fishing grounds of common squid fishing vessels, observed both by fishing vessels and satellites range from 9-, with the satellite-observed data having a larger range than the fishing vessel-based ones. The interannual distributions of the common squid fishing grounds in the East Sea are mostly concentrated in the TWC area in the southwestern part of the East Sea and in the coast of southern Honshu and Hokkaido in Japan. The interannual distributions of the nighttime fishing vessels are consistent with the catches investigated from the fishing vessel.

In order to understand the characteristics of oceanic environment in the coastal aquaculture waters of the East Sea, the observation of the CTD (temperature and salinity), dissolved oxygen, chlorophyll a and N/P (DIN (-N, -N, -N) : DIP(-P)) ratio was carried out at Sokcho, Jukbyon and Gampo in February, April, June, August, October, December 2013. Based on T(temperature)-S(salinity) diagram analysis, the water masses in the study area were divided into 3 groups; Tsushima Surface Water (TSW: temperatures and 31.04-33.75 salinities), Tsushima Middle Water (TMW: and 33.00-34.49), and North Korean Cold Water (NKCW: and 33.78-34.42). In winter, DO concentrations in the northern part were higher than those in southern part. In spring and fall, they were low in the surface layer, and increased in summer. Chl-a concentrations dominated in February, April, October and December. Chl-a concentrations were higher in June and August. In particular, the highest Chl-a concentration > was observed in the middle layer of Gampo in August. In February, April, June and December, the N/P ratio in the most of the water masses was less than the Redfield ratio (16), indicating that nitrate did act as a limiting factor in phytoplankton growth. On the contrary, in August and October, the N/P ratio in surface and sub-surface layer was greater than the Redfield ratio, suggesting that phosphate was a limiting factor.

East Sea Fisheries Research Institute, Gangneung, 210-861, Korea 요 약 : 동해에서 외양의 해양학적 현상으로 인하여 연안역에서 발생할 수 있는 성층 현상을 이해할 목적으로 2013년 2월 국립수산과학원의 해양조사 정선관측 자료와 함께 연안의 3개 지점(속초, 죽변, 감포)에서 조사한 CTD 자료를 분석하였다. 속초와 감포 연안은 혼합 상태였으며, 죽변 연안은 강항 성층을 이루고 있었다. 또한 해양 정선 조사에서 104선(죽변)의 연안쪽 정점에서도 마찬가지로 107선(속초)과 209선(감포)의 연안쪽 정점에 비해서 성층이 강하게 형성되어 있었다. 104선(죽변)의 정점 9의 깊이 200m층에서 4.0 의 양의 수온 편차를 보였으며 이것은 연안까지 이어져 양의 수온 편차를 나타내었으며, 10 등온선이 깊이 200m까지 아래로 오목한 형태를 나타내었다. 또한 104선의 정점 9를 중심으로 10 40cm/s의 속도로 시계 방향의 소용돌이가 형성되어 있었다. 이는 죽변 연안에서 나타난 성층은 울릉 난수성 소용돌이의 접안에 의해서 형성된 것임을 보여주었다. 난수성 소용돌의 변화는 동해에서 대구와 같은 냉수성 어종의 회유에 장애물이 될 수도 있어 수산 자원과의 관련성을 밝히는 것도 필요하리라 생각된다.핵심용어 : 성층, 시계 방향 소용돌이, 울릉 난수성 소용돌이, 접안, 수온 편차 Abstract : In order to see the stratification phenomenon in the coastal area induced by oceanographic conditions of the open sea, we analyzed the CTD (Conductivity-Temperature-Depth) data taken from the oceanographic survey on February 16∼28, 2013. The stratification in Jukbyun coast was stronger than those of Sokcho and Gampo coast. Jukbyun line (104 line in the Serial Oceanographic Observation of National Fisheries Research and Development Institute) showed the anticyclonic eddy in the vertical distribution of temperature. The isotherm of 10℃ was concaved to the depth of 200 m in the middle station (station no. 9) of the line 104. It showed above 4℃ in positive temperature anomaly in the depth of 100∼200m in the middle station (station no. 9) of the line 104. This positive temperature anomaly was stretched to the coastal area with shallower depth. It is suggested that the stratification in Jukbyun coast was resulted from the onshoring of the Ulleung warm eddy. The movement of warm eddy may be act as a block to migration of cold water fishes like cod.Key Words : Stratification, Anticyclonic eddy, Ulleung warm eddy, Onshoring, Temperature anomaly

We developed volumetric 3D display by adopting liquid crystal based fast switching active optical shutter and polarization controller. This method can enhance the depth perception by projecting the clear depth images without blurring the image.

The purpose of this study is to analyze seasonal variations of seaweed community structure according to ocean environment at three areas in the east coast of Korea. Mean water temperatures of Gosung, Samchuk, and Gyeongju were 8.3 ℃ , 11.2 ℃ , and 13.1 ℃ , respectively, during the growing winter season of 2011. Subtidal benthic macroalgal flora and community structure were investigated at the sites between February to November 2011. The numbers of seaweed species at the areas were 38, 12, and 15, respectively. The amounts of biomass were 7.35 kg m -2 , 1.80 kg m -2 , and 0.84 kg m -2 , respectively, during the period. The values of C/P, R/P, and (R+C)/P representing flora characteristics at Sokcho area were 0.1, 1.1, and 1.2, respectively. The values of flora characteristics at Samchuk were 0.3, 0.6, and 1.0, respectively. The values of flora characteristics at Gyeongju were 0.4, 4.0, and 1.2, respectively. Key Words : Algal flora, Water temperature, Community, Seaweed species

Time-series change in Gyeongpo beach shoreline was illustrated using DGPS(Differential Global Positioning System, resolution < 0.6m) observation from April, 2009 to April, 2010. The shoreline was subdivided into 12 areas, and westward and eastward movement of shoreline position at each area was calculated. In general, the shoreline moved toward sea during summer, and it moved toward land during winter. The southern and northern part of the shoreline had different pattern in time-series. The shoreline in the southern part moved toward sea during summer and moved toward land during winter, but time-series pattern of the shoreline in the northern part was more complicated than that in the southern part. Pattern of time-series change in the northern part was made up of three different types; the first is that the shoreline moves continuously toward land, and the second thing is that the shoreline's movement is the opposite to the southern part, and the third thing is that the shoreline maintains a state of equilibrium without any great fluctuation. The total length of the shoreline was the largest during winter and the smallest during summer. In general, time-series change in the shoreline had positive(+) relationship with sea surface pressure and wind speed.

The relative abundance of nitrate (N) over phosphorus (P) has increased over the period since 1980 in the marginal seas bordering the northwestern Pacific Ocean, located downstream of the populated and industrialized Asian continent. The increase in N availability within the study area was mainly driven by increasing N concentrations and was most likely due to deposition of pollutant nitrogen from atmospheric sources. Atmospheric nitrogen deposition had a high temporal correlation with N availability in the study area (r = 0.74 to 0.88), except in selected areas wherein riverine nitrogen load may be of equal importance. The increase in N availability caused by atmospheric deposition and riverine input has switched extensive parts of the study area from being N-limited to P-limited.

Based on the Results of Annual Monitoring Report of Korean Marine Environment in 2006, it was shown that the coastal area of the East Sea around Korean peninsula could be clearly divided into two parts: the area of upwelling and the North Korean Cold Current. In the upwelling area, the chlorophyll-a and nutrients were increased by the influence of the decrease of temperature and the increase of salinity. These mean that the appearance of cold water due to the upwelling causes nutrient rich water and also resulted in the high productivity.

In 2007, 43.5% mortality of the cultured oyster population occurred in Gamak Bay. Mortality rapidly increase in September and peak in October. To prevent future mass-mortality event, we investigated spawning and variation of oyster body composition. The main spawning period of culture oyster occurred from August to September. Condition index and body composition (protein and glycogen) appeared to be influenced by the spawning activity. Condition index and glycogen content in September were lowest (13.5% and 5.6 mg/g, respectively). However, protein, lipid and glycogen contents did not rapidly recover after the spawning activity. The data indicates that mass-mortality of cultured oysters in Gamak Bay may be due to deteriorated health, spawning activity, stress of the high water temperature and decreasing food resources.

Competitive power of pelagic fishery in Korea has been weakened by the domestic and international problems such as wage increase and exclusive economic zone. To make it worse, fishing fleet spends more than 80% of fishing time on searching fishing grounds. Real-time information on oceanographic data, temperature in particular, are likely to contribute to raise efficiency of fishing. However, available data obtained by satellite remote sensing, fixed buoy and drifting buoy, limited to sea surface or fixed positions. ARGO (Array for Real-time Geostrophic Oceanography), an international program, has delivered vertical profiles of temperature and salinity in the upper 2000m of the world ocean every 10 days using freely moving floats. We have developed real-time oceanographic information system for pelagic fishery based on the Argo data which has the contents of vertical profile, horizontal distribution and vertical section of temperature around fishing grounds and searched data can be download unrestrictedly. Comparison of skipjack catch with sea surface temperature and depth of derived from Argo data in the West Equatorial Pacific revealed that Argo data are able to help fishing fleet to find fishing grounds and to increase catch.

We developed 2D/3D switchable light-field camera system by using polarization-dependent micro lens array (PDMLA). Implemented system captured images in video frame rate (50fps) and reconstruction of 3D directional view and refocused image was successful.

Based on a time series of ocean climate indices and catch records for seven pelagic fish species in the Tsushima Warm Current (TWC) and Kuroshio-Oyashio Current (KOC) regions from 1910 to 2004, we detected regional synchrony in the long-term fluctuations of the fish populations and identified alternation patterns of dominant species related to climate shifts. The annual catches of Pacific herring, Japanese sardines, Japanese anchovies, jack mackerel, chub mackerel, Pacific saury and common squid in the TWC region fluctuated in phase with those in the KOC region, which suggests that they were controlled by the same basin-wide climate forcing. After the collapse of the herring fishery, the alternation sequence was: sardines (1930s), Pacific saury, jack mackerel, common squid and anchovies (), herring (), chub mackerel (1970s) and then sardines (1980s). As sardine biomass decreased in the late stages of the cool regime, catch of the other four species increased immediately during the warm period of the 1990s. Regional differences in the amplitude of long-term catch fluctuations for the seven pelagic fishes could be explained by regional differences in availability, fishing techniques and activity.

Environmental variables, fishing and biological data of the common squid, Todarodes pacificus were used to describe changes in structure, migration and abundance of the squid population in relation to ocean climate shifts. It was possible to consider the main groups of the squid (autumn and winter-spawned groups) as a single population to aid conservation in the waters around Korea and Japan (TWC and KOC regions). The patterns of yearly fluctuations in abundance of the squid population in the two regions were the same during 52 years of . The abundance of the squid began to decrease in both regions in the early 1970s, remained low in the 1980s and the main squid groups synchronously increased in the 1990s coincident with favorable changes of thermal conditions and plankton production in those ecosystems. The mechanisms of changes in the structure, distribution and abundance of common squid population in relation to current-mediated migration circuits are explained on the basis of phenological variables responding to climate shifts.

The cDNA of Crassostrea gigas HSP70 was cloned and rapid amplification of cDNA (RACE) techniques were used. The full length of HSP70 cDNA was 2045 bp, consisting of a 5' terminal untranslated region (UTR) of 80 bp, a 3' terminal UTR 146 bp, and an open reading frame (ORF) of 1829 bp encoding deduced 620 amino acids. The HSP70 cDNA contained HSP70 family signatures, ATP-GTP binding site motif, tetrapeptide (GGMP) and conserved carboxyl terminal region (EEVD) at C-terminal of deduced amino acid sequence. BLAST analysis revealed that the HSP70 gene has an extreme similarity of 98.9% with C. gigas (AF144646). Northern blotting was used to examine the expression of HSP70 mRNA in the gill tissue of the oyster obtained from surface, middle and bottom layers. The HSP70 mRNA observed the samples taken from middle and bottom layers in September and February, but samples from the surface layer did not find a signal intensity of HSP70 mRNA transcript. Consequently, it seems that the oyster occurring middle and bottom layer have been stressed during the period of summer and winter, which is associated with the massive mortality in Gamak bay.

The deposit is built up in the pipeline of the steelworks by the chemical reaction among COG (coke oven gas), BFG (blast furnace gas), moisture, and steel in the high temperature environment and obstructs the smooth gas flow. In this study a gamma‐ray system is developed to detect the deposit accumulated in pipelines and calculate the accumulation rate with respect to the cross section area of pipes. Cs‐137 is used as the gamma‐ray source and the system is designed to apply to pipes of various diameters. This system also includes the DB for storage and display of the measurement results so that it can be used for the efficient management of the pipelines.