• Journal of Environmental Science International
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• v.30 no.6
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• pp.465-474
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• 2021

This research investigated the characteristics of fine particle concentration and ionic elements of PM_2.5 during sea breeze occurrences during summertime in Busan. The PM₁₀ and PM_2.5 concentrations of summertime sea breeze occurrence days in Busan were 46.5 ㎍/m³ and 34.9 ㎍/m³, respectively. The PM₁₀ and PM_2.5 concentrations of summertime non-sea breeze occurrence days in Busan were 25.3 ㎍/m³ and 14.3 ㎍/m³, respectively. The PM_2.5/PM₁₀ ratios of sea breeze occurrence days and non-sea breeze occurrence days were 0.74 and 0.55, respectively. The SO₄^2-, NH₄⁺, and NO₃^- concentrations in PM_2.5 of sea breeze occurrence days were 9.20 ㎍/m³, 4.26 ㎍/m³, and 3.18 ㎍/m³ respectively. The sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR) of sea breeze occurrence days were 0.33 and 0.05, respectively. These results indicated that understanding the fine particle concentration and ionic elements of PM_2.5 during sea breeze summertime conditions can provide insights useful for establishing a control strategy of urban air quality.

• Ocean Systems Engineering
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• v.10 no.4
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• pp.373-397
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• 2020

Heave compensation is a vital part of various marine and offshore operations. It is used in various applications, including the transfer of cargo between two vessels in the open ocean, installation of topsides of an offshore structure, offshore drilling and for surveillance, reconnaissance and monitoring. These applications typically involve a load suspended from a hydraulically powered winch that is connected to a vessel that is undergoing dynamic motion in the ocean environment. The goal in these applications is to design a winch controller to keep the load at a regulated height by rejecting the net heave motion of the winch arising from ship motions at sea. In this study, we analyze and compare the performance of various control algorithms in stabilizing a suspended load while the vessel is subjected to changing sea conditions. The KCS container ship is chosen as the vessel undergoing dynamic motion in the ocean. The negative of the net heave motion at the winch is provided as a reference signal to track. Various control strategies like Proportional-Derivative (PD) Control, Model Predictive Control (MPC), Linear Quadratic Integral Control (LQI), and Sliding Mode Control (SMC) are implemented and tuned for effective heave compensation. The performance of the controllers is compared with respect to heave compensation, disturbance rejection and noise attenuation.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.3
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• pp.206-221
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• 2015

Supercavitation is a modern technique which can be used to surround an underwater vehicle with a bubble in order to reduce the resistance of the vehicle. When the vehicle is at low speed in the deep sea, the cavitation number is relatively big and it is difficult to generate a cavity large enough to envelope the vehicle. In this condition, the artificial cavity, called ventilated cavity, can be used to solve this problem by supplying gas into the cavity and can maintain supercavitating condition. In this paper, a relationship between the ventilation gas supply rate and the cavity shape is determined. Based on the relationship a ventilation rate control is developed to maintain the supercavitating state. The performance of the ventilation control is verified with a depth change control. In addition, dynamics modeling for the supercavitating vehicle is performed by defining forces and moments acting on the vehicle body in contact with water. Simulation results show that the ventilation control can maintain the supercavity of an underwater vehicle at low speed in the deep sea.

• Journal of Environmental Science International
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• v.27 no.1
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• pp.55-58
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• 2018

The purpose of this study was to evaluate the effect of sea urchin shell powder, used in broiler diet, on Esherichia coli and Salmonella in litter produced by the broilers. A total of 120 broiler chickens were fed 1 of 3 treatment diets (10 chickens per pen) in a randomized block design treatments with 4 replications. Sea urchin shell powder was used in the concentrations of 0.5% and 1% in the basal diets; the control diet was constituted of basal diet. During the 3-week feeding trials, none of the treatments significantly affected the E. coli populations in poultry litter at weeks 0 and 1, nor did they affect the and S. enterica populations at weeks 1 and 3. However, dietary sea urchin shell powder addition affected the population of E. coli at weeks 2 and 3, and that of S. entericaat weeks 0 and 2 (P<0.05). It is therefore concluded that the use of dietary sea urchin shell powder (0.5% and 1%) will be beneficial enough to reduce E. coli, rather than S. enterica in poultry litter over short-term periods.

• Journal of Environmental Science International
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• v.29 no.10
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• pp.1011-1014
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• 2020

The purpose of this study was to investigate the egg freshness and eggshell characteristics of old laying hens by adding sea urchin shell powder to the feed of such hens to achieve the objectives continuously pursued by environmental management, such as business profitability and waste resource utilization. A total of 90 Hy-Line Brown layers (66 weeks of age) were randomly divided into 2 treatments with 3 replicates, each of which consisted of 15 older layers, for 4 weeks. These treatments included a control (i.e., 0%) and 2% sea urchin shell powder. The 2% supplementation of sea urchin shell powder increased the Haugh unit (HU) at 2 and 4 weeks and eggshell strength at 4 wks compared to the controls (p<0.05). The HU at 0 weeks, eggshell thickness from 0 through 3 weeks, and eggshell strength at 0 and 2 weeks were not different between treatments (p>0.05). These results suggest that the addition of 2% sea urchin powder to the feed of laying hens improves egg freshness and eggshell strength in old laying hens.

• Fisheries and Aquatic Sciences
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• v.24 no.12
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• pp.400-405
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• 2021

In this study, the relationship between the growth of abalone and the presence of epibionts was investigated in abalone cultured in Goheung, Jeollanam-do, where there are severe problems high water temperatures and attachment. The experiment was conducted for eight months (May-December 2020), and 40 abalone were collected every month. Water temperature was at its highest at a range of 13.5℃-26.6℃ and dissolved oxygen levels were at their lowest at a range of 4.0-10.2 ㎍/L in August. The shell height (mm) of abalone grew to 117.7% (81.8 ± 1.9 mm) in cultures where epibionts were removed (ER) and 111% (77.4 ± 3.3 mm) where they were not (non-epibionts, NER). Their total weight (TW) and body weight increased significantly and steadily with ER, whereas the TW increased sharply after August with NER. In the condition index, no significant difference was observed between ER and NER. The monthly proportion of epibionts increased significantly in July, accounting for the value of 69.9% reached in December.

• Journal of Aquaculture
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• v.11 no.3
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• pp.345-352
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• 1998

The effect of starvation on the growth and hepatocyte nuclear size of larval rockfish Sebastes schlegeli and spotted sea bass Lateolabrax sp. were studied. The growth of total length and wet weight in both rockfish and spotted sea bass starved were lower than their control counter-parts. The nuclei sizes of parenchymal cells in the liver of rockfish and spotted sea bass were correlated with the nutritional status of their first-feeding larvae. The result suggested that hepatocyte nuclear size in rockfish and spotted sea bass could be used as an alternative indicator for the identification of starving condition and such karyometry might be criteria for evaluating the successful transition from endogenous to exogenous feeding regime.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.102-108
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• 2008

Many alternative biocidal additives were applied to antifouling paint to replace TBT, and Sea-Nine 211 is one of alternating organic booster compounds used in antifouling paint. In this study, extent of Sea-Nine 211 toxicity on marine benthic bivalve is evaluated. Sea-Nine 211 was injected to surf clam, Pseudocardium sachalinensis, that inhabitate northern part of Gangwon Province, Korea. Survival rate of the clam and xenobiotics metabolizing enzyme activities in digestive gland were measured during 4 day-exposure period. The results were compared with those of TBT exposed clam. There were no mortality of clam in the solvent (DMSO) control group and the three Sea-Nine 211 exposure groups (5, 25, 50 mg kg$^{-1}$ body weight), while the clam exposed to 1, 2 and 5 mg kg$^{-1}$ TBT chloride (TBTC) demonstrated 70, 30 and 0% survival rate, respectively. The Sea-Nine 211 exposure group showed a tendency of cytochrome P450 (CYP) induction according to the exposure duration, on the other hand, CYP content was decreased in the TBT exposure group. NADPH cytochrome P450 reductase activity slightly increase according to the exposure duration in the Sea-Nine 211 exposure group, while TBTC inhibit its activity as CYP content. Moreover, there was no significant change of NADH cytochrome b5 reductate activity in the clam epxosed to Sea-Nine 211. In the TBTC exposure group, its activity increased in early exposure period and then significantly decreased the rest of exposure period. All the results indicate that Sea-Nine 211 demonstrated a tendency to induce CYP level, while TBTC inhibits the CYP level, NADPH cytochrome P450 reductase and NADH cytochrome b5 reductase activities.

• Journal of Food Hygiene and Safety
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• v.6 no.3
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• pp.157-163
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• 1991

Salted sea mustard (Undaria pinnatifida) was irradiated (0, 2,4 kGy) and stored for 6 months at $10{\pm}1^{\circ}C\;and\;30{\pm}2^{\circ}C$, respectively. Quality deterioration of stored salted sea mustard was observed to closely relate with the growth of halophilic bacteria and yeast. Gamma irradiation with 2 to 4 kGy doses reduced initial microbial loads of salted sea mustard by 1 to 2 log orders, but had little influence on the propagation during storage. Organoleptic characteristics of the sample showed no signifiant difference between nonirradiated control and irradiated samples during storage. Thus, gamma irradiation was little effective for improving the microbiological and organoleptic qualities of salted sea mustard associated with its storage stability.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.12-15
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• 1994

To establish the sea surface temperature estimation scheme for the upcoming advanced remote sensor, the quasi-analytical solution of the approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the non-linear equation. To solve the simultaneous approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the nonlinear equation. To solve the simultaneous approximated radiative transfer equation at each channel, the constrained non-linear optimization technique is adopted. To define the coefficients of the approximated radiative transfer equation and the constraints, the satellite detected radiance and the total transmittance are computed from the 1350 kinds of simulated atmosphere / surface models via radiative transfer code. The verification from the simulated data show the sufficient result.