• Journal of Wetlands Research
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• v.23 no.2
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• pp.189-200
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• 2021

To improve the water quality of agricultural reservoirs, constructed wetlands are applied in many places. These are technologies that establish ecosystems and important design factors include water depth distribution, inflow and outflow, water flow distribution, hydraulic residence time, water quality treatment efficiency, aspect ratio, and the distribution of open water and covered water surfaces. For high efficiency during the operation of a constructed wetland, the design needs to be optimized and this requires consideration of the different types and length of the intake dam as well as the type and connection of wetland cells. Therefore, this study was conducted to investigate and suggest factors that needs to be considered during the design and for efficient operation measures through field surveys of 23 constructed wetlands that have been established and operated in agricultural reservoirs. Results of the field investigation shows that several sites were being operated improperly due to the malfunctioning or failure of the water level sensors, sedimentation in the intake dam, and clogging of the mechanical sluice frames. In addition, it was found that as the length of the inlet channel increases, the ecological disconnection between the intake dam upstream and the wetland outlet downstream also increases and was identified as a problem. Most of the wetlands are composed of 2 to 5 cells which can result to poor hydraulic efficiency and difficulty in management if they are too large. Moreover, it was found that the flow through a small wetland can be inadequate when there are too many cells due to excessive amounts of headloss.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.1
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• pp.13-18
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• 2009

Accurate solar radiation data are critical to evaluate major physiological responses of plants. For most upland crops and orchard plants growing in complex terrain, however, it is not easy for farmers or agronomists to access solar irradiance data. Here we suggest a simple method using a sun-slope geometry based topographical coefficient to estimate daily solar irradiance on any sloping surfaces from global solar radiation measured at a nearby weather station. An hourly solar irradiance ratio ($W_i$) between sloping and horizontal surface is defined as multiplication of the relative solar intensity($k_i$) and the slope irradiance ratio($r_i$) at an hourly interval. The $k_i$ is the ratio of hourly solar radiation to the 24 hour cumulative radiation on a horizontal surface under clear sky conditions. The $r_i$ is the ratio of clear sky radiation on a given slope to that on a horizontal reference. Daily coefficient for slope correction is simply the sum of $W_i$ on each date. We calculated daily solar irradiance at 8 side slope locations circumventing a cone-shaped parasitic volcano(c.a., 570m diameter for the bottom circle and 90m bottom-to-top height) by multiplying these coefficients to the global solar radiation measured horizontally. Comparison with the measured slope irradiance from April 2007 to March 2008 resulted in the root mean square error(RMSE) of $1.61MJ\;m^{-2}$ for the whole period but the RMSE for April to October(i.e., major cropping season in Korea) was much lower and satisfied the 5% error tolerance for radiation measurement. The RMSE was smallest in October regardless of slope aspect, and the aspect dependent variation of RMSE was greatest in November. Annual variation in RMSE was greatest on north and south facing slopes, followed by southwest, southeast, and northwest slopes in decreasing order. Once the coefficients are prepared, global solar radiation data from nearby stations can be easily converted to the solar irradiance map at landscape scales with the operational reliability in cropping season.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.10-19
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• 2014

Nozzle configurations and atmospheric conditions play a significant role in the infrared signature level of aircraft propulsion system. Various convergent nozzles of an unmanned aircraft under different atmospheric conditions are considered. An analysis of thermal flow field and nozzle surface temperature distribution is conducted using a compressible CFD code. It is shown that the IR level in rear direction is considerably reduced in deformed nozzles, whereas the IR level in adjacent azimuth angles is increased in aspect ratios around 6 due to the plume spreading effect caused by high aspect ratio of nozzles. In addition, an analysis of atmospheric transmissivity for various seasons and observation distance is conducted using the LOWTRAN 7 code and subsequently plume IR signature is calculated by considering atmospheric effects. It is shown that the IR signature is reduced significantly in summer season and near the band of carbon dioxide in case of relatively close distance.

• Korean Journal of Head & Neck Oncology
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• v.15 no.1
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• pp.70-75
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• 1999

Objectives: This study was designed to evaluate the methods of diagnosis and treatment of thyroid nodules. Materials and Methods : We performed a clinical review of patients with thyroid nodules, who were surgically treated at the Department of Surgery, College of Medicine, Chosun University from January 1996 to December 1998. Results: 1) The patients were divided into two groups; 65 patients(80.2%) with benign nodular disease and 16 patients(19.8%) with malignant disease. 2) The sex distribution showed a preponderance of females with a ratio of 5.2:1 in benign nodular disease and 3:1 in malignant disease. Benign nodules were more prevalent in patients in their 40's as compared to malignant nodules in patients in their 50's and 60's. 3) The most common duration of illness was 3 months, occurring in 45.7% of the total cases. 4) The most prominent symptom and sign was a palpable nodule in the anterior aspect of the neck. 5) The location of the nodule was ; 41 cases in the right lobe, 29 cases in the left lobe, and 11 cases in both lobes. 6) Thyroid scanning of 40 patients revealed cold nodules in 90.6% of benign nodules and in all malignant disease. 7) Fine needle aspiration cytology were performed in 32 cases of the 81 patients. Comparing with postoperative pathological findings, the results were the same in 87.5% of 32 cases. 8) Intra-operative frozen section study was performed in 56 cases of the 81 patients. Comparing with postoperative pathological finding, the results were same in 96.4% of the 56 cases. 9) The histopathological classification revealed that adenomatous goiters were the most common benign disease and papillary carcinomas were the most common malignant disease. 10) The most frequently employed operation for benign nodules and malignant disease was unilateral total lobectomy. When the metastasis was confirmed, lymphadenectomy and radical neck dissection was performed in malignant disease. 11) Important postoperative complications were transient hoarseness, transient hypocalcemia, hypothyroidism, wound bleeding, and hoarseness. Conclusions: The results of this study suggest that palpable nodules in anterior aspect of neck is revealed cold nodule by thyroid scanning and malignancy by fine needle aspiration cytology, which should be removed surgically. There is no difference in complication and survival rate with type of operation and lymphatic dissection. Therefore, procedure of operation is dependent on the site of nodule and involvement of lymph node.

• Journal of the Korean Society of Food Science and Nutrition
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• v.7 no.1
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• pp.35-39
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• 1978

In order to understand the diets of Gwangju city resident, nutrition survey was carried out through four years from 1974 to 1977. 1. Average intake of nutritional elements for an adult per day was 580. 25gr in 1974, 583.62gr in 1975, 599.13gr in 1976, and 597.72gr in 1977. 2. Average calorie distribution of the nutritional elements per adult per day was 13.51% protein, 4.70% fat and 81.08% carbohydrate in 1974; 11.6% protein, 7.1% fat and 81.3% carbohydrate in 1975; 15.0% protein, 4.9% fat and 80.1 % carbohydrate in 1976; 13.79% protein, 4.3% fat, and 82% carbohydrate in 1977. 3. The ratio of the animal protein to total protein consumed was 20.01% in 1974, 25.89% in 1975, 26.01% in 1976, and 29.38% in 1977. 4. In aspect of calorie, taken-in calorie was 2456.91 cal in 1974, 2515.10 cal in 1975, 2544.58 cal in 1976, and 2519.08 cal in 1977. However most of calorie were lower than the R.D.A. (3000cal). 5. The amount of ingested protein was 78.18 gr in 1974, 87.61 gr in 1975, 89,93 gr in 1976, and 81.65gr in 1977. The amount was higher than the R.D.A. (80gr) except 1974’s protein amount. 6. As for fat consumption, it was 27.18 gr in 1974, 40.96gr in 1975, 29.61gr in 1976, and 25.64gr in 1977. But these values were much lower than the R.D.A. (40gr) except for 1975’s. 7. In aspect of the minerals (Fe, Ca), intake of Ca was 462.34mg in 1974, 400.07 mg in 1975, 488.14 mg in 1976 and 440.95mg in 1977. The consumption of Ca was lower than the R.D.A. (600mg). Fe was 10.27mg in 1974, 8.54mg in 1975, 11.36mg in 1976 and 20.84mg in 1977. Most of them were higher than the R.D.A. (10mg) except 1975. 8. It was found that thiamine and riboflavin were ingested slightly higher than the R.D.A. (1.4mg, vit. $B_1$, 1.6mg, vit. $B_2$). The amount of niacin and ascorbic acid were also higher than the R.D.A. except 15.41mg of niacin in 1975.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.11-18
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• 2016

This study focused on examining the possibility for recycling of Fe-Si electric sheet. We manufactured Fe-6.5Si mother alloy using by Fe-Si electric sheet scrap for transformer core materials. And then, soft magnetic alloy powder which diameter and shape were $45{\sim}150{\mu}m$ and sphere type was prepared by gas atomization process. As we compared to commercial Fe-6.5Si powder, its diameter distribution and microstructure of recycled powder was a similar. To investigate the possibility of reusing the soft magnetic composite sheet for electronics, recycled powder was treated to have a high aspect ratio (AR), and we finally obtained the 65~66 AR and $2.3{\mu}m$ thickness powder. To release the residual stress of powder, heat treatment was conducted under $300{\sim}400^{\circ}C$, $N_2$ gas. And then, soft magnetic sheet was made by tape casting process using by those powders. After the density and permeability of tape was measured, and we confirmed that the recycled Fe-Si electric sheet scrap was possible to reuse the soft magnetic materials of electronics.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.646-651
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• 2017

Size and shape of carbon nanotube (CNT) agglomerates in the dilute phase of a bubbling fluidized bed ($0.15m\;i.d{\times}2.6m\;high$) have been determined by the laser sheet technique. Axial solid holdup distribution of the CNT particles showed S curve with dense phase and dilute phase in bubbling fluidization regime. Heywood diameter and Feret diameter of the CNT agglomerates in the dilute phase of bubbling fluidized bed increased with increasing gas velocity. The CNT particle number in the agglomerates increased with increasing of gas velocity. Aspect ratio increased and circularity, roundness and solidity decreased with increasing of gas velocity. A possible mechanism of agglomerates formation was proposed based on the obtained information.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.147-158
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• 2004

For stiffened plates composed of composite materials, many researchers have used a finite element method which connected isoparametric plate elements and beam elements. However, the finite element method is difficult to reflect local behavior of stiffener because beam elements are transferred stiffness for nodal point of plate elements, especially the application is limited in case of laminated composite structures. In this paper, for analysis of laminated composite stiffened plates, 3D shell elements for stiffener and plate are employed. Reissner-Mindlin's first order shear deformation theory is considered in this study. But when thickness will be thin, isoparamatric plate bending element based on the theory of Reissner-Mindlin is generated by transverse shear locking. To eliminate the shear locking and virtual zero energy mode, the substitute shear strain field is used. A deflection distribution is investigated for simple supported rectangular and skew stiffened laminated composite plates with arbitrary orientation stiffener as not only variation of slenderness and aspect ratio of the plate but also variation of skew angle of skew stiffened plates.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.18.1-18.1
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• 2011

Some applications of carbon nanotubes (CNTs) as field emitters, such as x-ray tubes and microwave amplifiers, require high current emission from a small emitter area. To emit the high current density, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects including high crystallinity, aspect ratio, distribution density, height uniformity, adhesion on a substrate, low outgassing rate during electron emission in vacuum, etc. In particular, adhesion of emitters on the substrate is one of the most important parameters to be secured for high current field emission from CNTs. So, we attempted a novel approach to improve the adhesion of CNT emitters by incorporating metal oxide layers between CNT emitters. In our previous study, CNT emitters were fabricated on a metal mesh by filtrating the aqueous suspensions containing both highly crystalline thin multiwalled CNTs and thick entangled multiwalled CNTs. However, the adhesion of CNT film was not enough to produce a high emission current for an extended period of time even after adopting the metal mesh as a fixing substrate of the CNT film. While a high current was emitted, some part of the film was shown to delaminate. In order to strengthen the CNT networks, cobalt-nickel oxides were incorporated into the film. After coating the oxide layer, the CNT tips seemed to be more strongly adhered on the CNT bush. Without the oxide layer, the field emission voltage-current curve moved fast to a high voltage side as increasing the number of voltage sweeps. With the cobalt-nickel oxide incorporated, however, the curve does not move after the second voltage sweep. Such improvement of emission properties seemed to be attributed to stronger adhesion of the CNT film which was imparted by the cobalt-nickel oxide layer between CNT networks. Observed after field emission for an extended period of time, the CNT film with the oxide layer showed less damage on the surface caused by high current emission.

• Atmosphere
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• v.17 no.3
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• pp.217-230
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• 2007

Using the Lorenz-95 simple model, which can simulate many atmospheric characteristics, we compare the performance of ensemble strategies such as bred vectors, the bred vectors rotated (to be orthogonal to each bred member), and the Ensemble Transform Kalman Filter (ETKF). The performance metrics used are the RMSE of ensemble means, the ratio of RMS error of ensemble mean to the spread of ensemble, rank histograms to see if the ensemble member can well represent the true probability density function (pdf), and the distribution of eigen-values of the forecast ensemble, which can provide useful information on the independence of each member. In the meantime, the orthogonal bred vectors can achieve the considerable progress comparing the bred vectors in all aspects of RMSE, spread, and independence of members. When we rotate the bred vectors for orthogonalization, the improvement rate for the spread of ensemble is almost as double as that for RMS error of ensemble mean compared to the non-rotated bred vectors on a simple model. It appears that the result is consistent with the tentative test on the operational model in KMA. In conclusion, ETKF is superior to the other two methods in all terms of the assesment ways we used when it comes to ensemble prediction. But we cannot decide which perturbation strategy is better in aspect of the structure of the background error covariance. It appears that further studies on the best perturbation way for hybrid variational data assimilation to consider an error-of-the-day(EOTD) should be needed.