• Journal of the Korean Society for Marine Environment & Energy
• /
• v.9 no.1
• /
• pp.45-54
• /
• 2006

The study was to review methods by which a ship can unfold and tow an oil boom by attaching the opening apparatus to an oil boom through experiments. The shape and dimension of the opening apparatus were designed with the measurement value of the towing tension load of the oil boom and the dimension of winch drum of the oil boom installed in the ship considered. For the field experiment to identify the performance of the opening apparatus, opening apparatuses were prepared to have the dimension of $3.0m^2$ and $6.0m^2$ which is 91% and 75% of the calculation value for type B and C respectively. As a result, T(kg), the value of tension in type B oil boom according to the towing speed(v) change when two ships are towed together were proved to be $T=920v^{1.1}\;and\;T=500v^{0.9}$ in case the distance is 100 m and 50 m. Based on the result, the dimension of the opening apparatus for type B and C oil boom was calculated as $3.3m^2$ and $8.0m^2$ respectively. When unfolding and towing by attaching the opening apparatus and 200 m of towing line at both ends of type B and type C oil boom, the maximum width of the opening apparatus was shown as 114 m and 95 m in average(width of opening/total length of oil boom: 33% and 57%) in the towing speed of 1.5 kt. It was evaluated that the opening apparatus could concentrate the spilled oil in a good performance. However as far as the increase rate of oil boom opening width according to the length of the towing line is debatable, the increase rate is remarkably reduced when it is lengthened from 100 m to 150 m and to 200 m although it showed extreme increase of 31% and 40% when the length of the towing line was changed from 50 m to 100 m. Therefore, it is inferred that the towing line should be maintained more or less 100 m to get good spread efficiency of the opening apparatus. Additionally, if the towing speed is faster than 1.5 kt, the opening width was narrowed because of the reduced spread efficiency and the shape of the oil boom can be unstable because of the partial sinking of the oil boom, run over waves, or flap of skirt. Thus the reasonable towing speed can be within 1.5 kt for the operation of the opening apparatus.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.3 no.3
• /
• pp.3-12
• /
• 2000

The field surveys and the measurements of seawater temperatures were conducted every month from 1997 to 1999, and the distributions of seawater temperature were simulated and reproduced by a three dimensional hydrodynamic numerical model over the southern waters of Cheju island. In order to estimate the marine environmental capacity for the reception of the heat loads of cooling water discharged from Hwasoon Thermal Power Plant(HTPP) in the study area, the simulations for predicting the situation of unfavorable environment in which marine organisms might not be satisfied with change in seawater temperature were peformed using a three dimensional hydrodynamic numerical model by controlling quantitatively the heat loads of cooling water from HTPP Currently, HTPP discharges cooling water of 35.9℃ into the sea as much as 112,800m³/day in summer. As the results of simulations, the more the heat loads from the power plant increase, the more increase the seawater temperatures around the water areas adjacent to the power plant. In case the heat loads of cooling water from HTPP become about 5 times as high as the present loads, seawater temperatures at near-shore waters adjacent to HTPP appear to be increased to the extent of 0.5℃ above the existing seawater temperature in summer. The marine environmental capacity for the reception of thermal discharge from HTPP is estimated to be about 530×10/sup 6/kcal/day which is equivalent to the increase of a factor of 2 in the temperature of cooling water without any change in the discharge rate of cooling water or which is equivalent to the increase of a factor of 4.6 in the discharge rate of cooling water without any change in the temperature of cooling water. Comparing the case of the increase in the discharge rate of cooling water with the case of the increase in the temperature of cooling water on the basis of the same heat loads of 530×10/sup 6/kal/day, the former case is expected to increase seawater temperature a little higher and to extend the area affected by heat loads a little broader.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.28 no.1
• /
• pp.1-11
• /
• 2010

This study examines the authentic meaning, location, garden layout, and structural characteristics of Suwoojae(守愚齋), the birth house of Garam Byungi Lee, which was the very epitome of the traditional house structure based on literature review, field survey, and the existing measured drawings. The followings explain how rusticity and spirit of scholars, the core concepts of Garam's poetry, were featured in structural and spacial arrangements of Suwoojae as well as its location and physical layout. 1. Suwoojae is enclosed by Cheonho mountain which fans out of Noryoung mountains in East and located on the tail of Yongwha mountain in West. It has proved to be Yangtack Myoungdang according to the Poongsoo theory, Inguljiryoungron; The energy of earth at a certain location results in the better fortune together with the energy emitted from human body. 2. Suwoojae is an official local monument which was built in 1844, late Joesoen Dynasty by Joheung Lee, Garam's grandfather. Some parts of inner-structure connect with the kitchen in the shape of called Gopae. Suwoojae consists of 4 Sarangchae, 3 Gobangchae, and a Jangdokdae behind Anchae. 3. Since inner and outer walls of Suwoojae are distinctly separate from the main structure, its look varies significantly from different angles. Suwoojae, in its entirety, discloses Garam's philosophy, ideas, and ideology on life and the universe. 4. Apricot trees, Japanese-magnolias, aromatic-trees, crape myrtle, white-magnolias, camellia-trees were planted on the left of the walls, and persimmon trees, jujube trees, plum trees, quince trees were at the inner-yard. Especially, trifoliate orange trees a natural monument of Jeonrabukdo draw substantial attention from visitors. 5. The main garden facilities are located in front of Sarangchae: A rectangle pond(14.72m in length and 3.87m in height), the surroundings of the pond and Anchae, rocks that have distinctive shapes. In general, the garden was designed to incorporate the scenery around Suwoojae as a part of its structure and contain the love for nature and aesthetic sense. 6. It seems that the natural surroundings of Suwoojae had helped form motives of Garam's poetry and assisted him in finding subject-matters and identifying the themes of his works. This is well revealed in his poem, Seungwoonjungee.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.9 no.4
• /
• pp.203-215
• /
• 2006

Field observations on the spatio-temporal distribution of organic matter of the surface sediment were carried out at 15 stations in the central parts of the South Sea of Korea from April 2002 to January 2003. The range of water temperature and salinity in bottom waters, mud content and water content of surface sediment were $8.06{\sim}23.35^{\circ}C,\;29.20{\sim}34.51\;psu,\;71.2{\sim}99.9%$ and $38.7{\sim}68.9%$, respectively. Measured parameters on the surface sediments of ignition loss (IL), chemical oxygen demand (CODs), phaeopigment, particulate organic carbon (POC) and particulate organic nitrogen (PON) also ranged in $3.9{\sim}l2.5%,\;9.60{\sim}44.05\;mgO_2/g-dry,\;1.58{\sim}29.51\;{\mu}g/g-dry,\;3.12{\sim}13.01\;mgC/g-dry$ and $0.49{\sim}2.00\;mgN/g-dry$, respectively. The spatio-temporal distribution of organic matter demonstrated higher concentrations offshore than at lesions near the coastal line. Higher concentrations occurred in the summer and spring. The results indicated that the origin of organic matter in surface sediments in the central part of the South Sea was autochthonous rather than allocthonous because the organic matter had an average C/N ratio of 6.44 (${\pm}0.51$). However, the composition of autochthonous organic matter was mainly derived from detritus rather than living phytoplankton, which was Indicated by the results of the POC/phaeopigment ratio. A principal component analysis (PCA) indicated that 73.2% of the variability in the data was described by two factors: 1) an 'environmental factor concerning the accumulation of materials (57.3%)' and 2) 'origin of organic matter and the composition by primary production (15.9%)'. The sedimentary environment in the central part of the South Sea was divided into four regions from the factor score of the PCA by the concentrations of organic matter and the composition ratio of organic matters from phytoplankton in surface sediments.

• Journal of the Korean Society of Radiology
• /
• v.11 no.5
• /
• pp.361-370
• /
• 2017

In the Brain MRI, RF Pulse is irradiated on the human body in order to acquire an image. At this time, a considerable part of the irradiated RF Pulse energy is absorbed as it is in our body. This will raise the temperature of the human body, but depending on the extent of exposure, it will affect the human body. The change of the SAR and the temperature of the head according to the change of the magnetic field strength is examined. And to investigate the difference in results depending on the use of dental implant. In the human head model, 64 MHz RF Pulse frequency generated from 1.5 T, 128 MHz RF Pulse frequency generated from 3.0 T, and 298 MHz RF Pulse frequency generated from 7.0 T send a frequency and experiment was performed using dental implant using the XFDTD program, we measured the SAR and body temperature changes around the head. The SAR value showed up to about 5800 times the difference at the RF Pulse frequency of 256 MHz, when with dental implant than without dental implant and as the frequency increased, the use of the dental implant increased difference in the SAR value. The change of the temperature of the head showed a temperature rise nearly 2 to 4 times when with dental implant than without dental implant. As the RF Pulse frequency increase, the SAR value increase, but the change of the temperature of the head decrease. Because of as the frequency increase, wavelength is smaller and the more the amount absorbed by the surface of the human. Physiological and biochemical studies of the human body ar necessary through studies of the presence of dental implant and the cause of reaction caused by change in the RF Pulse frequency.

• International Journal of Ocean System Engineering
• /
• v.2 no.3
• /
• pp.185-194
• /
• 2012

A Macroscopic combination of two or more distinct materials is commonly referred to as a "Composite Material", having been designed mechanically and chemically superior in function and characteristic than its individual constituent materials. Composite materials are used not only for aerospace and military, but also heavily used in boat/ship building and general composite industries which we are seeing increasingly more. Regardless of the various applications for composite materials, the industry is still limited and requires better fabrication technology and methodology in order to expand and grow. An example of this is that the majority of fabrication facilities nearby still use an antiquated wet lay-up process where fabrication still requires manual hand labor in a 3D environment impeding productivity of composite product design advancement. As an expert in the advanced composites field, I have developed fabrication skills with the use of machinery based on my past composite experience. In autumn 2011, the Korea government confirmed to fund my project. It is the development of a composite sanding machine. I began development of this semi-robotic prototype beginning in 2009. It has possibilities of replacing or augmenting the exhaustive and difficult jobs performed by human hands, such as sanding, grinding, blasting, and polishing in most often, very awkward conditions, and is also will boost productivity, improve surface quality, cut abrasive costs, eliminate vibration injuries, and protect workers from exposure to dust and airborne contamination. Ease of control and operation of the equipment in or outside of the sanding room is a key benefit to end-users. It will prove to be much more economical than normal robotics and minimize errors that commonly occur in factories. The key components and their technologies are a 360 degree rotational shoulder and a wrist that is controlled under PLC controller and joystick manual mode. Development on both of the key modules is complete and are now operational. The Korean government fund boosted my development and I expect to complete full scale development no later than 3rd quarter 2012. Even with the advantages of composite materials, there is still the need to repair or to maintain composite products with a higher level of technology. I have learned many composite repair skills on composite airframe since many composite fabrication skills including repair, requires training for non aerospace applications. The wind energy market is now requiring much larger blades in order to generate more electrical energy for wind farms. One single blade is commonly 50 meters or longer now. When a wind blade becomes damaged from external forces, on-site repair is required on the columns even under strong wind and freezing temperature conditions. In order to correctly obtain polymerization, the repair must be performed on the damaged area within a very limited time. The use of pre-impregnated glass fabric and heating silicone pad and a hot bonder acting precise heating control are surely required.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.3 no.4
• /
• pp.37-55
• /
• 2000

Two-dimensional numerical experiments and field surveys have been conducted to clarify some environmental variations in the flow and sedimentation in the adjacent seas after the construction of a tidal embankment. Velocities of flow and water levels in the bay decreased after the construction of the barrage. When the freshwater was instantly released into the bay, the conditions of flow were unaltered, with the exception of a minor variation in velocities and tidal levels around the sluices at the ebb flow. The computational results showed that freshwater released at the low water reached the outside of the bay and then returned to the inside with the tidal currents at the high water. The front sea regions of the embankment had a variety of sedimentary phases such as a clayish silt, a silty clay and a sandy clayish silt. However, a clayish silt was prevalent in the middle of the bay. On the other hand, the skewness, which reflects the behaviour of sediments, was $\{pm}0.1$ at the front regions of the embankment while it was more than ±0.3 in the middle of the bay. Analytical results of drilling samples acquired from the front of the sluice gates showed that the lower part of the sediments consists of very fine silty or clayish grains. The upper surface layer consisted of shellfish, such as oyster or barnacle with a thickness of 40～50 cm. Therefore, it seemed that the lower part of the sediments would have been one of intertidal zones prior to the embankment construction while the upper shellfish layer would have been debris of shellfish farms formed in the adjacent seas after the construction of the embankment. This shows the difference of sedimentary phases reflected the influence of a tidal embankment construction.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.4
• /
• pp.304-309
• /
• 2015

To evaluate the degree of contamination caused by oil spill accident in the sea, the in-situ sensors which are based on the scientific method are needed in the real site. The sensors which are based on the fluorescence detection theory can provide the useful data, such as the concentration of oil. However these kinds of sensors commonly are composed of the ultraviolet (UV) light source such as UV mercury lamp, the multiple excitation/emission filters and the optical sensor which is mainly photomultiplier tube (PMT) type. Therefore, the size of the total sensing platform is large not suitable to be handled in the oil spill field and also the total price of it is extremely expensive. To overcome these drawbacks, we designed the fluorimeter for the oil spill detection which has compact size and cost effectiveness. Before the detail design process, we conducted the experiments to measure the excitation and emission spectrum of oils using five different kinds of crude oils and three different kinds of processed oils. And the fluorescence spectrometer were used to analyze the excitation and emission spectrum of oil samples. We have compared the spectrum results and drawn the each common spectrum regions of excitation and emission. In the experiments, we can see that the average gap between maximum excitation and emission peak wavelengths is near 50 nm for the every case. In the experiment which were fixed by the excitation wavelength of 365 nm and 405 nm, we can find out that the intensity of emission was weaker than that of 280 nm and 325 nm. So, if the light sources having the wavelength of 365 nm or 405 nm are used in the design process of fluorimeter, the optical sensor needs to have the sensitivity which can cover the weak light intensity. Through the results which were derived by the experiment, we can define the important factors which can be useful to select the effective wavelengths of light source, photo detector and filters.

• Korean Journal of Environmental Biology
• /
• v.40 no.4
• /
• pp.413-422
• /
• 2022

Barnea manilensis is a bivalve which bores soft rocks, such as, limestone or mudstone in the low intertidal zone. They make burrows which have narrow entrances and wide interiors and live in these burrows for a lifetime. In this study, the morphology and the microstructure of the valve of rock-boring clam B. manilensis were observed using a stereoscopic microscope and FE-SEM, respectively. The chemical composition of specific part of the valve was assessed by energy dispersive X-ray spectroscopy (EDS) analysis. 3D modeling and structural dynamic analysis were used to simulate the boring behavior of B. manilensis. Microscopy results showed that the valve was asymmetric with plow-like spikes which were located on the anterior surface of the valve and were distributed in a specific direction. The anterior parts of the valve were thicker than the posterior parts. EDS results indicated that the valve mainly consisted of calcium carbonate, while metal elements, such as, Al, Si, Mn, Fe, and Mg were detected on the outer surface of the anterior spikes. It was assumed that the metal elements increased the strength of the valve, thus helping the B. manilensis to bore sediment. The simulation showed that spikes located on the anterior part of the valve received a load at all angles. It was suggested that the anterior part of the shell received the load while drilling rocks. The boring mechanism using the amorphous valve of B. manilensis is expected to be used as basic data to devise an efficient drilling mechanism.

• Korean Journal of Soil Science and Fertilizer
• /
• v.29 no.3
• /
• pp.226-235
• /
• 1996

This pot experiment was conducted to investigate the changes of leaching in percolated water of paddy soil in which rice was cultivated in conditions of 0%, 5%. 30% addition of bituminous and anthracite fly ash respectively in greenhouse. pH in percolated water was higher in non cultivated plot than in cultivated plot. pH of the fly ash treated plot was higher than that of the control plot. pH in the cultivated plot decreased gradually during the cultivation. The contents of $NH_4-N$, $NO_3-N$ and K in percolated water decreased rapidly after mid-July, and was very low in the cultivated plot. Over the cultivation time, P contents in percolated water was very low. $SiO_2$, contents in percolated water decreased rapidly after June. Na contents in percolated water was highest in mid-June and then decreased gradually. In the cultivated plot, Ca contents in percolated water was higher than that in the control plot. During the cultivation, Ca contents in percolated water decreased gradually. But, in later-term of cultivation. Ca contents in percolated water was relatively Mgh. Mg contents in percolated water decreased after mid-July, but decreased continuously till the later-term of cultivation. EC in the percolated water was highest in mid-June. and then decreased gradually. EC of fly ash treated plot was higher than that of the control plot. The soil pH was increased and phosphate content in the soil was accumulated very high by application of fly ashes in paddy field after rice cultivation. Fly ash treatment did not increase the contents of elements in percolated water compared with the control plot. The difference between anthracite and bituminous fly ash was not so clear. Fly ash treatment, inhibited early growth and tillering. But, in later-term of cultivation, the inhibition effects of nonproductive tillering was expected. Fly ash treatment will be good if it was applicated after last year's harvest because leaching would happen over fallowing time. Contents of inorganic elements in percolated water of fly ash treated plot was not so high compared with that in the control plot.