• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.10 no.4
• /
• pp.227-235
• /
• 1977

The noise pressure scattered underwater on account of the engine revolution of a pole and liner, Kwan-Ak-San(G. T. 234.96), was measured at the locations of Lat. $34^{\circ}47'N$, Long. $128^{\circ}53'E$ on the 16th of August 1976 and Lat. $34^{\circ}27'N$, Long. $128^{\circ}23'E$ on the 28th of July, 1977. The noise pressure passed through each observation point (Nos. 1 to 5), which was established at every 10m distance at circumference of outside hull was recorded when the vessel was cruising and drifted. In case of drifting, the revolution of engine was fixed at 600 r. p. m. and the noise was recorded at every 10 m distance apart from observation point No. 3 in both horizontal and vertical directions with $90^{\circ}$ toward the stern-bow line. In case of cruising, the engine was kept in a full speed at 700 r.p.m. and the sounds passed through underwater in 1 m depth were also recorded while the vessel moved back and forth. The noise pressure was analyzed with sound level meter (Bruel & Kjar 2205, measuring range 37-140 dB) at the anechoic chamber in the Institute of Marine Science, National Fisheries University of Busan. The frequency and sound waves of the noise were analyzed in the Laboratory of Navigation Instrument. From the results, the noise pressure was closely related to the engine revolution shelving that the noise pressure marked 100 dB when .400 r. p. m. and increase of 100 r. p. m. resulted in 1 dB increase in noise pressure and the maximum appeared at 600 r. p. m. (Fig.5). When the engine revolution was fixed at 700 r. p. m., the noise pressures passed through each observation point (Nos. 1 to 5) placed at circumference of out side hull were 75,78,76,74 and 68 dB, the highest at No.2, in case of keeping under way while 75,76,77,70 and 67 dB, the highest at No.3 in case of drifting respectively (Fig.5). When the vessel plyed 1,400 m distance at 700 r.p.m., the noise pressure were 67 dB at the point 0 m, 64 dB at 600m and 56 dB at 1,400m on forward while 72 at 0 m, 66 at 600 m and 57 dB at 1,400 m on backward respectively indicating the Doppler effects 5 dB at 0 m and 3 dB at 200 m(Fig.6). The noise pressures passed through the points apart 1,10,20,30,40 and 50 m depth underwater from the observation point No.7 (horizontal distance 20 m from the point No.3) were 68,75,62,59,55 and 51 dB respectively as the vessel was being drifted maintaining the engine revolution at 600 r. p. m. (Fig. 8-B) whereas the noise pressures at the observation points Nos.6,7,8,9 and 10 of 10 m depth underwater were 64,75,55,58,58 and 52 dB respectively(Fig.8-A).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.12 no.3
• /
• pp.125-130
• /
• 1979

In this paper, the noise pressure propagated in the air on account of the engine revolution of a stern trawler, Sae-Ba-Da(G. T. 2275.71) was measured at the check points No.1 through No.43 when the vessel was cruising, towing nets, and drifting. The experiment was carried out in the period from August 23 to October 22, 1978 at the locations of lat. $33^{\circ}$ 47'N, long. $127^{\circ}$ 34'E; lat. $34^{\circ}$ 24'N, long. $128^{\circ}$ 23'E; and lat. $6^{\circ}$ 01'N, long. $108^{\circ}$ 04'E. In case of cruising, noise on the weather deck came from funnel noise. The highest noise pressure was 92dB at observation point No.9 where tile noise pressure from main engine was 105dB when the engine was operated at 730rpm and $12^{\circ}$ sorely propeller pitch. The noise measured was reduced to 90dB at observation point No.9 when the screw propeller pitch was changed to $8^{\circ}$ that resulted in reduction of engine to 103dB. In case of towing net, the main engine revolution and screw propeller pitch was fixed at 730rpm and $8^{\circ}$ respectively. But the engine noise pressure was increased up to 106dB due to the towing resistance by 14 tons of the nets, and the noise pressure was 90dB at No.9 point. A hight noise was also generated from screw because of the towing reoistance and could be measurable even in the wall of the insulated freezing room. When the vessel was drifting: the noise pressure from the generator operated, at 720rpm was 100dB. This caused 87dB noise pressure at No.9 point. The noise pressure in the boarding or residence sections was 45 to 60dB in each case of cruisinrg towing net or drifting but it was so high as 82dB on the open deck that voice could hardly be heap.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.31 no.2
• /
• pp.186-194
• /
• 1998

Species composition and biomass of intertidal benthic algae were studied at the coast of Yonggwang Nuclear Power Plant area and its adjacent stations over 4 seasons (October 1995-August 1996), Of 68 species identified, 7 were Cyanophyta, 12 were Chlorophyta, 14 were Phaeophyta and 35 were Rhodophyta. The largest number of algal species (44) was found at Sangnok, the northernmost station of the study area, whereas the smallest number of species (15) was found from Tongho, ca. 13 km north of the power plant site. Number of species showed highest during the spring (44) and minimum was recorded in autumn (28). Biomass per unit area showed maximum in spring ($189.5\;g\;dry\;wt{\cdot}m^{-2}$ in average) and minimum in winter ($107.9\;g\;dry\;wt{\cdot}m^{-2}$ in average). Biomass values exhibited a wide range of variation among the stations, ranging from a low of $22.0\;g\;dry\;wt{\cdot}m^{-2}$ in annual average at Tongho to a high of $295.7g\;dry\;wt{\cdot}m^{-2}$ in average at Sangnok. Dominant species in biomass were Corallina pilulifera, Sargassum thunbergii, Gymnogongrus flabelliformis and Enteromorpha compressa. There have been little variation in the dominant algal species around the power plant site during the past 10 years and also these algae appeared throughout the west coast of Korea with higher frequency.

• Geophysics and Geophysical Exploration
• /
• v.11 no.1
• /
• pp.34-40
• /
• 2008

Underwater seismic refraction with advanced interpretation approaches makes important contributions to shallow marine exploration and geotechnical investigations in Australia's coastal areas. A series of case studies are presented to demonstrate the recent applications of continuous and static USR methods to river crossing and port infrastructure projects at various sites around Australia. In Sydney, static underwater seismic refraction (USR) with bottom-placed receivers and borehole seismic imaging assisted the development of improved geotechnical models that reduced construction risk for a tunnel crossing of the Lane Cove River. In Melbourne, combining conventional boomer reflection and continuous USR with near-bottom sources and receivers improved the definition of a buried, variably weathered basalt flow and assisted dredging assessment for navigation channel upgrades at Geelong Ports. Sand quality assessment with continuous USR and widely spaced borehole information assisted commercial decisions on available sand resources for the reclamation phase of development at the Port of Brisbane. Buried reefs and indurated layers occur in Australian coastal sediments with the characteristics of laterally limited, high velocity, cap layers within lower velocity materials. If these features are not recognised then significant error in depth determination to deeper refractors can occur. Application of advanced refraction inversion using wavefront eikonal tomography to continuous USR data obtained along the route of a proposed offshore pipeline near Fremantle allowed these layers and the underlying bedrock refractor to be accurately imaged. Static USR and the same interpretation approach was used to image the drowned granitic regolith beneath sediments and indurated layers in the northern area of Western Australia at a proposed new berthing site where deep piling was required. This allowed preferred piling sites to be identified, reducing overall pile lengths. USR can be expected to find increased application to shallow marine exploration and geotechnical investigations in Australia's coastal areas as economic growth continues and improved interpretation methods are developed.

• Journal of the Korean association of regional geographers
• /
• v.2 no.1
• /
• pp.51-67
• /
• 1996

There are three main rice-growing regions in the United States: the prairie region along the Mississippi River Valley in eastern Arkansas; the Gulf Coast prairie region in southwestern Louisiana and southeastern Texas; and the Central Valley of California. The Central Valley of California is producing about 23% of the US rice(Fig. 1). In California. most of the crop has been produced in the Colusa, Sutter, Butte, Glenn Counties of the Sacramento Valley since 1912, when rice was commercially grown for the first time in the state(Fig. 2). Roughly speaking, the average annual area sown to rice in California is about 300,000 acres to 400,000 acres during the last forty years(Fig. 3). California rice is grown under a Mediterranean climate characterized by warm, dry, clear days, and a long growing season favorable to high photosynthetic rates and high rice yields. The average rice yield per acre is probably higher in California than in any other rice-growing regions of the world(Fig. 4). A dependable supply of irrigation water must be available for a successful rice culture. Most of the irrigation water for California rice comes from the winter rain and snow-fed reservoir of the Sierra Nevada mountain ranges. Less than 10 percent of rice irrigation water is pumped from wells in areas where surface water is not sufficient. It is also essential to have good surface drainage if maximum yields are to be produced. Rice production in California is highly mechanized, requiring only about four hours of labor per acre. Mechanization of rice culture in California includes laser-leveler technology, large tractors, self-propelled combines for harvesting, and aircraft for seeding, pest control, and some fertilization. The principal varieties grown in California are medium-grain japonica types with origins from the cooler rice climates of the northern latitudes (Table 1). Long-grain varieties grown in the American South are not well adapted to California's cooler environment. Nearly all the rice grown recently in California are improved into semidwarf varieties. Choice of variety depends on environment, planting date, quality desired, marketing, and harvesting scheduling. The Rice Experiment Station at Biggs is owned, financed, and administered by the rice industry. The station was established in 1912, as a direct result of the foresight and effort of Charles Edward Chambliss of the United States Department of Agriculture. Now, The station's major effort is the development of improved rice varieties for California.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.9 no.4
• /
• pp.243-252
• /
• 2006

Influence of the increasing carbon dioxide concentration in seawater on various marine organisms is assessed in this article with regard to the impacts of anthropogenic $CO_2$ introduced into surface or deep oceans. Recent proposals to sequester $CO_2$ in deep oceans arouse the concerns of adverse effects of increased $CO_2$ concentration on deep-sea organisms. Atmospheric introduction of $CO_2$ into the ocean can also acidify the surface water, thereby the population of some sensitive organisms including coral reefs, cocolithophorids and sea urchins will be reduced considerably in near future (e.g. in 2100 unless the increasing trend of $CO_2$ emission is actively regulated). We exposed bioluminescent bacteria and benthic amphipods to varying concentrations of $CO_2$ and also pH for a short period. The ${\sim}l.5$ unit decrease of pH adversely affected test organisms. However, amphipods were not influenced by decreasing pH when HCl was used for the seawater acidification. In this article, we reviewed the biological adverse effects of $CO_2$ on various marine organisms studied so for. Theses results will be useful to predict the potential risks of the increase of $CO_2$ concentrations in seawater due to the increase of atmospheric $CO_2$ emission and/or sequestration of $CO_2$ in deep oceans.

• Clean Technology
• /
• v.13 no.1 s.36
• /
• pp.54-63
• /
• 2007

Even traces of CO in the hydrogen-rich feed gas to proton exchange membrane fuel cells (PEMFC) poison the platinum anode electrode and dramatically decrease the power output. In this work, a variety of catalytic materials consisting of $Cu/Ce_xZr_{1-x}O_2$, (x = 0.0-1.0) were synthesised, characterized and tested for CO oxidation and preferential oxidation of CO (PROX). These catalysts prepared by hydrothermal and deposition-precipitation methods. The catalysts were characterized by XRD, XRF, SEM, BET, $N_2O$ titration and oxygen storage capacity (OSC) measurement. The effects of composition of the support and degree of excess oxygen were investigated fur activity and $CO_2$ selectivity with different temperatures. The composition of the support markedly influenced the PROX activity. Among the various $Cu/Ce_xZr_{1-x}O_2$ catalysts having different composition, $Cu/Ce_{0.9}Zr_{0.1}O_2$ and $Cu/Ce_{0.7}Zr_{0.3}O_2$ showed the highest activities (>99%) and selectivities (ca.50%) in the temperature range of $150{\sim}160^{\circ}C$. It was found that by using of $Ce_xZr_{1-x}O_2$ mixed oxide support which possesses a high oxygen storage capacity, oxidation-reduction activity of Cu-based catalyst was improved, which resulted in the increase of catalytic activity and selectivity of CO oxidation in excess $H_2$ environments.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.9 no.3
• /
• pp.215-221
• /
• 1976

In this study, noise arresting effect of the noise control room from the transmission of surrounding noise was tested when the packing noise control rooms were set up in the test room in which the prerecorded noise from an engine room was reradiated at the same level as the original pressure. The inner space of control room A is $3.389m^3(1.19\times1.19\times2.14m)$ having walls furnished with plywood board 9mm in thickness and noise control room door$(60\times45cm) $ and illumination lamp are placed. In case of the control room B, noise absorption board(10mm fiber board which holds the corntype concavity with diameter of 5mm, depth 5mm, space 15mm) is adhered to the internal ceiling and styrol foam boards(20mm) to the walls. The other struction is same as the control room A. Type C is the same as B except wool board(Glass Fiber, 33mm) on the walls. Type D is same as type A except that the thickness of wall is 12mm and wood pyramid type cone$(5\times5\times13cm)$ is adhered to the ceiling ana walls(Fig. 1). When the recorded noise and vibrated noise were controlled in various levels. The noise pressure which passed through the control rooms was measured by sound level meter(Bruel & Kjar 2205, measuring range 37-140dB). In order to calculate the absorption rate in the control rooms the noise pressure was measured at different distances when the recorded noise pressure was radiated. The followings are the results obtained from the experiment. 1. When the noise pressure of the test room was 60dB, transmission rate of type A was $69.7\%$ and increased $3.3\%$ per 10dB. At the same condition, the rate was $53.9\%$ and increased $4.5\%$ per 10dB in type D. Type D was the most effective in noise arresting of the four and the effect was D,C,B and A in order(Fig.2). 2. When the oscillator sound and vessels noise were radiated in 1,000Hz, at one meter distance to the type A and D, the oscillator sound pressure were 77dB and 73dB, while the vessels noise pressure were 73.3dB and 66.2dB respectivley(Fig.3). 3. Refering to the influence of the frequency to the lower oscillator sound(1,000Hz) pressure, both type C and D were almost same at 140cm but type C was 0.3dB lower than type D at 20cm distance(Fig.4).

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.20 no.2
• /
• pp.121-129
• /
• 2014

Marine algal flora and community structure were seasonally investigated at four sites in the vicinity of the Igidae on the southern east coast of Korea from May 2010 to February 2011. A total of 66 species including 9 of Chlorophyta, 14 of Phaeophyta, 43 of Rhodophyta were found during the survey period. Among these species, 16 species were found throughout the year. Seasonal mean biomass in wet weight was 123.6 (spring), 2,061.6 (summer), 412.0 (autumn), 678.9 (winter) $g{\cdot}m^{-2}$. Maximum biomass was recorded in summer($2,061.6g{\cdot}m^{-2}$), and minimum was recorded in spring($123.6g{\cdot}m^{-2}$). Spatial maximum and minimum species number were recorded at station 3 and 4(50 species) and at station 1(47 species). At station 1, 2 directly exposure on Yongho and Daeyeon cheon (stream) run off, and discharge from Nambu sewage treatment plants near coastal area, species diversity was relatively low and dominant species were similar throughout four seasons. The R/P, C/P and (R+C)/P value reflecting flora characteristics were 3.07, 0.64 and 3.71, respectively. The flora investigated could be classified into six functional groups such as coarsely branch form 39.39 %, sheet form 30.30 %, thick leather form 13.64 %, filamentous form 12.12 %, crustose form 3.03% and jointed calcareous form 1.52 % during survey period. The number of marine algae species in Igidea were 96 species at 1996 to 1997 and 66 species at 2010 to 2011, respectively. The change of seaweed species is due to the pollution loaded from sewage treatment plant and stream. We thus recommend that the positive maintenance control method like sewage treatment, for the protection of seaweed bed should be proceeded to near coastal area.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.66 no.3
• /
• pp.190-200
• /
• 2021

The heading response of rice varieties, originated from South Korea, North Korea, and northern China, was examined under the temperature and day-length conditions of 10 low-temperature regions in North Korea. When 30-day-old broadcast tray-raised seedlings (BS) were used, only one or a few varieties reached the heading stage within the safe marginal heading date (SMHD) under the Hamhung, Pyonggang, Huichon, and Kanggye conditions. In the Yangdok and Sinpo environments, no varieties reached heading until SMHD. The South Korean varieties that reached the heading stage between SMHD and late marginal heading date (LMHD) were Jinbuol, Baegilmi, Joun, Jopum, Jinok, Jopyeong, Sanhomi, and Odae for the Hamhung, Pyonggang, Huichon, and Kanggye; Joun for Sinpo; and none for Yangdok, Kimchaek, Sonbong, and Chunggang environments. The number of days to heading (DTH) was positively correlated among all 10 regions. Reduced DTH in the 30-day-old pot tray-raised seedlings (PS), compared to BS, was not consistent with varieties and regions. Reduced DTH in PS, compared to BS, was the largest in Jinok and Sonbong9 among the South and North Korean varieties, respectively, whereas it was small in the northern Chinese varieties. The South Korean varieties that headed until SMHD in PS were Jinok for the Hamhung, Pyonggang, Yangdok, Sinpo, and Kanggye environments; and Jinbuol, Jopum, and Jinok for the Huichon condition. In the Kimchaek and Chunggang conditions, Jinok reached the heading stage within LMHD. With the use of PS for some responsive varieties such as Jinok, varietal adaptability could be improved to the conditions of low-temperature regions in North Korea. None of the PS or BS among the tested varieties reached the heading stage until LMHD for the Chongjin and Sonbong conditions.