• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.9 no.1
• /
• pp.1-18
• /
• 1973

For regulating the depth of midwater trawl nets towed at the optimum constant speed, the changes in the shape of warps caused by adding a weight on an arbitrary point of the warp of catenary shape is studied. The shape of a warp may be approximated by a catenary. The resultant inferences under this assumption were experimented. Accordingly feasibilities for the application of the result of this study to the midwater trawl nets were also discussed. A series of experiments for basic midwater trawl gear models in water tank and a couple of experiments of a commercial scale gears at sea which involve the properly designed depth control devices having a variable attitude horizontal wing were carried out. The results are summarized as follows: 1. According to the dimension analysis the depth y of a midwater trawl net is introduced by $$y=kLf(\frac{W_r}{R_r},\;\frac{W_o}{R_o},\;\frac{W_n}{R_n})$$) where k is a constant, L the warp length, f the function, and $W_r,\;W_o$ and $W_n$ the apparent weights of warp, otter board and the net, respectively, 2. When a boat is towing a body of apparent weight $W_n$ and its drag $D_n$ by means of a warp whose length L and apparent weight $W_r$ per unit length, the depth y of the body is given by the following equation, provided that the shape of a warp is a catenary and drag of the warp is neglected in comparison with the drag of the body: $$y=\frac{1}{W_r}\{\sqrt{{D_n^2}+{(W_n+W_rL)^2}}-\sqrt{{D_n^2+W_n}^2\}$$ 3. The changes ${\Delta}y$ of the depth of the midwater trawl net caused by changing the warp length or adding a weight ${\Delta}W_n$_n to the net, are given by the following equations: $${\Delta}y{\approx}\frac{W_n+W_{r}L}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}{\Delta}L$$ $${\Delta}y{\approx}\frac{1}{W_r}\{\frac{W_n+W_rL}{\sqrt{D_n^2+(W_n+W_{r}L)^2}}-{\frac{W_n}{\sqrt{D_n^2+W_n^2}}\}{\Delta}W_n$$ 4. A change ${\Delta}y$ of the depth of the midwater trawl net by adding a weight $W_s$ to an arbitrary point of the warp takes an equation of the form $${\Delta}y=\frac{1}{W_r}\{(T_{ur}'-T_{ur})-T_u'-T_u)\}$$ Where $$T_{ur}^l=\sqrt{T_u^2+(W_s+W_{r}L)^2+2T_u(W_s+W_{r}L)sin{\theta}_u$$ $$T_{ur}=\sqrt{T_u^2+(W_{r}L)^2+2T_uW_{r}L\;sin{\theta}_u$$ $$T_{u}^l=\sqrt{T_u^2+W_s^2+2T_uW_{s}\;sin{\theta}_u$$ and $T_u$ represents the tension at the point on the warp, ${\theta}_u$ the angle between the direction of $T_u$ and horizontal axis, $T_u^2$ the tension at that point when a weights $W_s$ adds to the point where $T_u$ is acted on. 5. If otter boards were constructed lighter and adequate weights were added at their bottom to stabilize them, even they were the same shapes as those of bottom trawls, they were definitely applicable to the midwater trawl gears as the result of the experiments. 6. As the results of water tank tests the relationship between net height of H cm velocity of v m/sec, and that between hydrodynamic resistance of R kg and the velocity of a model net as shown in figure 6 are respectively given by $$H=8+\frac{10}{0.4+v}$$ $$R=3+9v^2$$ 7. It was found that the cross-wing type depth control devices were more stable in operation than that of the H-wing type as the results of the experiments at sea. 8. The hydrodynamic resistance of the net gear in midwater trawling is so large, and regarded as nearly the drag, that sweeping depth of the gear was very stable in spite of types of the depth control devices. 9. An area of the horizontal wing of the H-wing type depth control device was $1.2{\times}2.4m^2$. A midwater trawl net of 2 ton hydrodynamic resistance was connected to the devices and towed with the velocity of 2.3 kts. Under these conditions the depth change of about 20m of the trawl net was obtained by controlling an angle or attack of $30^{\circ}$.

• Ecology and Resilient Infrastructure
• /
• v.4 no.3
• /
• pp.169-179
• /
• 2017

This study analyzed the aspect of bed change according to the stable channel design on the Wonju River to quantitatively evaluate habitat suitability (HS). According to the result of evaluating stable channel of object section in the Wonju River, 17 sections among total 20 sections were stable and 3 sections were unstable. Physical disturbance improvement evaluation (PDIE) was the range average showed good disturbance condition with a range average of 112.17 points. Habitat suitability index of Zacco Koreanus, the most dominant species of the Wonju River, was used for analysis of physical habitat for fish. According to the physical habitat analysis result, HS was 0.16 and weighted usable area (WUA) was $347.68m^2$. The methods of improving/introducing/removing structures and dredging stream channel were used for stable channel design of unstable channel, and analyzed PDIE according to the aspect of bed change and changes in habitat suitability. Stable channel design was possible in 19 sections in times of structures improvement/introduction/removal, and PDIE was 117.53 points, HS was 0.14 points, and WUA was $313.37m^2$. Stable channel design was possible in all 20 sections when dredging the stream channel. PDIE was 116.50 points, HS was 0.16, and WUA was $332.14m^2$. Therefore, this study obtained channel design measures that can improve physical soundness and stability of the Wonju River, and it was analyzed that it will have no impact on changes of physical disturbance and physical habitat. Furthermore, this study analyzed velocity and depth of each section and appearance frequency of riffle and pool to analyze correlation between physical disturbance and physical habitat. According to the analysis result, it was identified that the analysis of riffle and pool showed similar result as the evaluation result of physical habitat.

• Clinical and Experimental Pediatrics
• /
• v.46 no.3
• /
• pp.277-283
• /
• 2003

Purpose : Craniopharyngiomas are often accompanied by severe endocrine disorders. Although there is universal growth hormone deficiency(GHD), the resulting growth pattern is very heterogeneous. We report the growth and endocrine outcome of 44 children with craniopharyngioma, with emphasis on initial symptoms, growth before and during growth hormone(GH) treatment and spontaneous growth in spite of GHD. Methods : We performed a retrospective study of 44 children treated at our centre between 1984 and 2002. Results : About 30% of patients had symptoms suggesting endocrine disorder at diagnosis. After surgery, multiple endocrinopathies were almost universal. Before GH therapy, height velocity was $8.00{\pm}2.71cm/yr$ in the normal growth group(n=11) and $1.79{\pm}1.10cm/yr$ in the subnormal growth group(n=7) during the first year and during the second year, $6.76{\pm}2.49cm/yr$ and $2.29{\pm}1.33cm/yr$, respectively. There was no difference of body mass index(BMI) change between before and after surgery in the two groups. Height standard deviation score(SDS) was $-1.46{\pm}0.74$ in the normal growth group and $-0.43{\pm}0.97$ in the subnormal growth group. Before GH treatment height SDS was $-1.31{\pm}1.25$ and BMI was $20.46{\pm}3.60$. During GH treatment, height SDS increased to $-0.60{\pm}1.37$ in the first, and to $-0.41{\pm}1.54$ in the second year(P<0.05), but BMI did not change significantly. Conclusion : The endocrine morbidity could develop in most children with craniopharyngioma before and after the operation and should be managed properly. Although all treated patients benefit from GH therapy, further studies are necessary to find out the possible mechanism of growth regulation in normally growing children, despite GH deficient.

• Journal of Oral Medicine and Pain
• /
• v.32 no.4
• /
• pp.421-429
• /
• 2007

Some researchers suggested that tactile sensor system would be useful in evaluating masticatory muscles of TMD patients, but there were few studies on the effects of chewing with time. The aim of this study was to investigate the change of elasticity and stiffness for masseter and temporal muscles of normal subjects before, during and after gum chewing and to obtain the baseline data for further researches on the elasticity and stiffness for masticatory muscles of TMD patients. Stiffness and elasticity of their anterior temporalis and inferior masseter muscle were measured bilaterally by a tactile sensor system. Each subject was instructed to sit on a chair for evaluation of masticatory muscles. Before operating the sensor, the thickest skin area over anterior temporalis and inferior masseter muscles were selected as the points to be pressed by a tactile sensor, and marked with a pen. While the teeth of subjects were lightly contacted, the probe of the tactile sensor was placed perpendicularly over the marked point over the skin, followed by computer-controlled movement including gently pressing straight down on the muscle for a second and retracting. All subjects were instructed to chew gum (Excellent Breath, Taiyo Co., Japan) bilaterally with a velocity of 2 times per second for 40 minutes after the first measurement had been performed for the baseline data of all subjects. The measurements had been repeated during chewing with 10 minutes of interval and continued for 40 minutes with same interval after chewing. Resultantly, the decrease of elasticity and the increase of stiffness in masticatory muscles can be seen significantly within 10 minutes after chewing and those were maintained during chewing without significant change with chewing time. The elasticity of muscles was recovered within 10 minutes after stopping chewing, but the stiffness was recovered more lately than elasticity by about 10 minutes. Based on these results, it can be concluded that elasticity and stiffness of muscles would be good indicators to evaluate the masticatory muscles objectively, when more supported by further researches.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.22 no.3
• /
• pp.88-102
• /
• 2017

Long-term changes in bathymetry and grain size of surface sediments were investigated for understanding depositional sedimentary environments in the channelized Yeongsan River Estuary, Korea. The results revealed that an average depth of the estuary had decreased up to 2.1 m from 1982 to 2006, while it had increased to 0.3 m from 2006 to 2012. The rapid decrease of the water depth from 1982 to 2006 was due to the vast deposition of mud caused by the change of water course and flow velocity after the estuary was dammed. Meanwhile the increase of the water depth from 2006 to 2012 may be associated with multiple erosional processes, including a dredging at the southern part of the estuary and other erosions from the dike sluice expansion work. Considering the water-depth change and tidal-level variation in the study area, an depositional rate in the estuary is estimated to be 8~9 cm/yr for the last 2 decades (1982~2006). The sediments of Yeongsan River Estuary are largely composed of silt-clay mixtures: overall, silt is distributed mainly in the shallow area of the estuary edge, while clay is confined to the deep area of the estuary center. Mean grain size of the sediments is 6.0 Ø on average in 1997, 7.8 Ø on average in 2005 and 7.7 Ø on average in 2012, respectively, suggesting that the sediments became finer due to the increase of silt and clay contents in 1997~2005. Furthermore, several lines of evidences, including the comparison between the amounts of the sediment influx discharged from the Yeongsan River and the sediments in the estuary, and the changes in distribution pattern of silt and clay contents implying that they moved from offshore to estuary dike, indicate that the mud sediments are originated mainly from the offshore, not from the river.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.31 no.3
• /
• pp.101-114
• /
• 2019

In this study, we carry out the numerical simulation to trace the yearly shoreline change of Mang-Bang beach, which is suffering from erosion problem. We obtain the basic equation (One Line Model for shoreline) for the numerical simulation by assuming that the amount of shoreline retreat or advance is balanced by the net influx of longshore and cross-shore sediment into the unit discretized shoreline segment. In doing so, the energy flux model for the longshore sediment transport rate is also evoked. For the case of cross sediment transport, the modified Bailard's model (1981) by Cho and Kim (2019) is utilized. At each time step of the numerical simulation, we adjust a closure depth according to pertinent wave conditions based on the Hallermeier's analytical model (1978) having its roots on the Shield's parameter. Numerical results show that from 2017.4.26 to 2017.10.15 during which swells are prevailing, a shoreline advances due to the sustained supply of cross-shore sediment. It is also shown that a shoreline temporarily retreats due to the erosion by the yearly highest waves sequentially occurring from mid-October to the end of October, and is followed by gradual recovery of shoreline as high waves subdue and swells prevail. It is worth mentioning that great yearly circulation of shoreline completes when a shoreline retreats due to the erosion by the higher waves occurring from mid-March to the end of March. The great yearly circulation of shoreline mentioned above can also be found in the measured locations of shoreline on 2017.4.5, 2017.9.7, 2017.11.7, 2018.3.14. However, numerically simulated amount of shoreline retreat or advance is more significant than the physically measured one, and it should be noted that these discrepancies become more substantial for the case of RUN II where a closure depth is sustained to be as in the most morphology models like the Genesis (Hanson and Kraus, 1989).

• Journal of the Korean Institute of Landscape Architecture
• /
• v.48 no.5
• /
• pp.80-88
• /
• 2020

With the issuance of one-week fine dust emergency reduction measures in March 2019, the public's anxiety about fine dust is increasingly growing. In order to assess the application of air purifying plant-based bio-filters to public facilities, this study presented a method for measuring pollutant reduction effects by creating an indoor environment for continuous discharge of particle pollutants and conducted basic studies to verify whether indoor air quality has improved through the system. In this study conducted in a lecture room in spring, the background concentration was created by using mosquito repellent incense as a pollutant one hour before monitoring. Then, according to the schedule, the fine dust reduction capacity was monitored by irrigating for two hours and venting air for one hour. PM₁₀, PM_2.5, and temperature & humidity sensors were installed two meters front of the bio-filters, and velocity probes were installed at the center of the three air vents to conduct time-series monitoring. The average face velocity of three air vents set up in the bio-filter was 0.38±0.16 m/s. Total air-conditioning air volume was calculated at 776.89±320.16㎥/h by applying an air vent area of 0.29m×0.65m after deducing damper area. With the system in operation, average temperature and average relative humidity were maintained at 21.5-22.3℃, and 63.79-73.6%, respectively, which indicates that it satisfies temperature and humidity range of various conditions of preceding studies. When the effects of raising relatively humidity rapidly by operating system's air-conditioning function are used efficiently, it would be possible to reduce indoor fine dust and maintain appropriate relative humidity seasonally. Concentration of fine dust increased the same in all cycles before operating the bio-filter system. After operating the system, in cycle 1 blast section (C-1, β=-3.83, β=-2.45), particulate matters (PM₁₀) were lowered by up to 28.8% or 560.3㎍/㎥ and fine particulate matters (PM_2.5) were reduced by up to 28.0% or 350.0㎍/㎥. Then, the concentration of find dust (PM₁₀, PM_2.5) was reduced by up to 32.6% or 647.0㎍/㎥ and 32.4% or 401.3㎍/㎥ respectively through reduction in cycle 2 blast section (C-2, β=-5.50, β=-3.30) and up to 30.8% or 732.7㎍/㎥ and 31.0% or 459.3㎍/㎥ respectively through reduction in cycle 3 blast section (C-3, β=5.48, β=-3.51). By referring to standards and regulations related to the installation of vegetation bio-filters in public facilities, this study provided plans on how to set up objective performance evaluation environment. By doing so, it was possible to create monitoring infrastructure more objective than a regular lecture room environment and secure relatively reliable data.

• Clinical and Experimental Pediatrics
• /
• v.49 no.3
• /
• pp.305-311
• /
• 2006

Purpose : GnRH analogues(GnRHa) are used to treat central precocious puberty(CPP). However, in some patients, the GV decrease is so remarkable that it impairs predicted adult height(PAH); and there fore, the addition of growth hormone(GH) is suggested. We analysed the growth changes during two years and final adult height(FAH) in girls with idiopathic CPP treated with combined therapy, compared with those of girls treated with GnRHa alone. Methods : For the analysis, we classified the patients, who was treated for longer than two years, into three groups depending on the initial PAH and combination of GH; PAH_L, treated with GnRHa and PAH less than midparental height(MPH) - 5 cm. PAH_H, treated with GnRHa and PAH greater than MPH - 5 cm. GnRHa＋GH, combined GH treatment, regardless of PAH before treatment. We analysed the GV and PAH change during the first two years and FAH. Results : In PAH_L, the PAH(SDS) at first year of therapy was significantly increased to $153.5{\pm}6.5cm(-1.4{\pm}1.3)$ from $149.7{\pm}6.4cm(-2.1{\pm}1.3)$ before treatment(P=0.004). In PAH_H, there was no significant increase in PAH during the two years of treatment. During the first year of combination of GH and GnRHa, GV and PAH increased significantly. We observed significant increases in FAH, comparing to the initial PAH in the PAH_L and GnRHa＋GH groups. The height gains(FAH - initial PAH) were significantly higher in the PAH_L and GnRHa＋GH groups than that in the PAH_H group. Conclusion : This study suggests the FAH and height gains are improved in patients, whose predicted adult height before treatment was shorter than those with higher predicted adult height, with the treatment of GnRHa alone or in combination with GH. GH could not improve the final adult height, but compensated the growth in patients whose growth velocity was decelerated by GnRHa alone.

• The Korean Journal of Food And Nutrition
• /
• v.19 no.3
• /
• pp.279-287
• /
• 2006

This study was carried out to investigate the influences of modified starches on suppression of retrogradation in Korean rice cake for their optimization, Garaeduk. Based upon studying Avrami equation, the Avrami exponent n value of all the experiment samples was found to be 1.03 ${\sim}$ 1.37 in the influence of modified starches on retrogradation of the rice cake. This means that the retrogradation of the Korean rice cake occurred instantly after the crystallization of starch particles in the Korean rice cake formulated by modified starches. The highest Avrami exponent n value was indicated in the control sample. The rate constant k of retrogradation in the Korean rice cake formulated by modified starches showed comparatively low and appeared to be the lowest in the Korean rice cake formulated by SHPP. This tendency was shown well in the time constant(1/k) of retrogradation velocity. According to the DSC analysis, the onset temperature of gelatinization in thermal characteristics showed somewhat high in case of addition of modified starch into the Korean rice cake on storage time and the SHPP was slowly gone up. In peak temperature of gelatinization in thermal characteristics of the DSC analysis, SSOS and ASA were increased a little in comparison with the control. The control was comparatively high increase. Melting enthalphy of all samples added with modified starches (SSOS: 21.1${\rightarrow}$23.7${\rightarrow}$24.1, ASA: 21.1${\rightarrow}$24.8${\rightarrow}$25.4) appeared to be lower than that of the Korean rice cake without modified starches(21.2${\rightarrow}$26.1${\rightarrow}$27.1). The Korean rice cake added with SHPP was shown to be the lowest in the increasing rate of melting enthalpy(20.9${\rightarrow}$21.4${\rightarrow}$22.1). Heat spreadability of all the samples in Martin melting diameter was revealed to be good in order of control, ASA, SSOS, SHPP and especially the Korean rice cake added with SHPP was shown to be the best in heat spreadability. In color, sensory examination and textural characteristic of the Korean rice cake added with modified starches, the L$^*$value was not changed practically with the storage time and seemed to be stable. The a$^*$ value of the samples was followed by control(2.21${\rightarrow}$5.34: 141.6%), ASA (2.01${\rightarrow}$4.22: 110.0%), SSOS (2.78${\rightarrow}$4.87: 75.2%) and SHPP (2.12${\rightarrow}$3.40: 60.4%) in order of color change. Also the b$^*$ value of the samples was followed by control(4.32${\rightarrow}$6.35: 47.0%), ASA (4.66${\rightarrow}$5.73: 23.0%), SSOS (4.90${\rightarrow}$5.89: 20.2%) and SHPP (4.89${\rightarrow}$5.12: 4.7%) and there was the least (or no) color change with the SHPP. Textural characteristics of samples was shown to be the highest in case of modified starch addition and especially SHPP appeared to be the best in texture.

• Clean Technology
• /
• v.25 no.4
• /
• pp.316-323
• /
• 2019

In order to enhance combustion efficiency and reduce atmosphere pollutants, it is essential to measure carbon monoxide (CO) concentration precisely in combustion exhaust. CO is the important gas species regarding pollutant emission and incomplete combustion because it can trade off with NOx and increase rapidly when incomplete combustion occurs. In the case of a steel annealing system, CO is generated intentionally to maintain the deoxidation atmosphere. However, it is difficult to measure the CO concentration in a combustion environment in real-time, because of unsteady combustion reactions and harsh environment. Tunable Diode Laser Absorption Spectroscopy (TDLAS), which is an optical measurement method, is highly attractive for measuring the concentration of certain gas species, temperature, velocity, and pressure in a combustion environment. TDLAS has several advantages such as sensitive, non-invasive, and fast response, and in-situ measurement capability. In this study, a combustion system is designed to control the equivalence ratio. Also, the combustion exhaust gases are produced in a Liquefied Petroleum Gas (LPG)/air flame. Measurement of CO concentration according to the change of equivalence ratio is confirmed through TDLAS method and compared with the simulation based on Voigt function. In order to measure the CO concentration without interference from other combustion products, a near-infrared laser at 4300.6 cm^-1 was selected.