• Journal of the Korean Society for Marine Environment & Energy
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• 제10권4호
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• pp.193-200
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• 2007

The purpose of this study is investigate to water quality, pH, turbidity, salinity, nutrients, SS, DO, COD, ${NH_4}^+$-N, ${NO_2}^-+{NO_3}^-$-N, TN, TP, ${PO_4}^{3-}$-P in ditches and seawater of the Hwawon, southwestern coastal area of Korea. Two stations of the ditch, one station at outfall from reservoir of the coastal development and 15 stations of seawater were measured in August just after a 96.5 mm rainfall and in dry season of November 2006. The sampling time were divided into a rainy and dry season based on turbidity, SS, salinity and nutrients difference of distributions that was evidence as a inflow of pollutants from the developing coastal land area. The pH, turbidity, salinity and SS were high and showed different from between surface and bottom in near the developing of coastal land than the other stations after a strong rainfall over 90 mm while it were not varied in vertical and horizontal concentration profile in dry season. The other nutrients were showed the same concentrations gradient patterns. In opposition to expectations, the SS in dry season was higher than in the rainy season due to upwelling by the wind and strong current. It appears that the researched coastal seawater qualities were mainly effected by the inflow of freshwater from the ditches and drain from the reservoir of the developing land area during strong rainfall while the seawater qualities were mainly effected by the wind and strong current in dry season.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제13권5호
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• pp.403-411
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• 2020

Since the analog circuit of the beta ray sensor circuit for the true random number generator and the power and ground line used in the comparator circuit are shared with each other, the power generated by the digital switching of the comparator circuit and the voltage drop at the ground line was the cause of the decreasein the output signal voltage drop at the analog circuit including CSA (Charge Sensitive Amplifier). Therefore, in this paper, the output signal voltage of the analog circuit including the CSAcircuit is reduced by separating the power and ground line used in the comparator circuit, which is the source of digital switching noise, from the power and ground line of the analog circuit. In addition, in the voltage-to-voltage converter circuit that converts VREF (=1.195V) voltage to VREF_VCOM and VREF_VTHR voltage, there was a problem that the VREF_VCOM and VREF_VTHR voltages decrease because the driving current flowing through each current mirror varies due to channel length modulation effect at a high voltage VDD of 5.5V when the drain voltage of the PMOS current mirror is different when driving the IREF through the PMOS current mirror. Therefore, in this paper, since the PMOS diode is added to the PMOS current mirror of the voltage-to-voltage converter circuit, the voltages of VREF_VCOM and VREF_VTHR do not go down at a high voltage of 5.5V.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제13권7호
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• pp.1393-1398
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• 2009

Conventionally, etching is first considered for microelectronics fabrication process and is specially important in process of a-Si:H thin film transistor for LCD. In this paper, we stabilize properties of device by development of wet and dry etching process. The a-Si:H TFTs of this paper is inverted staggered type. The gate electrode is lower part. The gate electrode is formed by patterning with length of 8 ${\mu}$m${\sim}$16 ${\mu}$m and width of 80${\sim}$200 ${\mu}$m after depositing with gate electrode (Cr) 1500 ${\AA}$under coming 7059 glass substrate. We have fabricated a-SiN:H, conductor, etch-stopper and photo resistor on gate electrode in sequence, respectively. The thickness of these thin films is formed with a-SiN:H (2000 ${\mu}$m), a-Si:H(2000 ${\mu}$m) and n+a-Si:H (500 ${\mu}$m), We have deposited n-a-Si:H, NPR(Negative Photo Resister) layer after forming pattern of Cr gate electrode by etch-stopper pattern. The NPR layer by inverting pattern of upper gate electrode is patterned and the n+a-Si:H layer is etched by the NPR pattern. The NPR layer is removed. After Cr layer is deposited and patterned, the source-drain electrode is formed. In the fabricated TFT, the most frequent problems are over and under etching in etching process. We were able to improve properties of device by strict criterion on wet, dry etching and cleaning process.

• The KIPS Transactions:PartC
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• 제18C권3호
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• pp.143-150
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• 2011

The adoption of VoIP is continuously increasing in public institutions, private enterprises and households due to cheaper cost and various supplementary services. Also, it is expected to spread widely the use of VoIP in mobile environment through the increasing use of smartphone. With the growing concern over the incidents of VoIP service while the VoIP service has become increasingly. Especially eavesdropping, it is possible to invade user privacy and drain the secret of company. So, it is important to adopt the protocols for VoIP secure communication. VoIP security protocols are already adopted in public institutions, but it is not adopted in private enterprises and households. In addition, it is necessary to verify whether the VoIP security protocol could be adopted or not in mobile VoIP due to its limited computing power. This paper compared the VoIP security protocol under fixed network and mobile network through performance evaluation. Finally, we found that it is possible to adopt the VoIP security protocols in mobile network.

• Journal of the Korean Geosynthetics Society
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• 제13권4호
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• pp.33-43
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• 2014

Recently, the case to construct the structure on the soft clayey ground has increased and in order to the reduction of the cost of construction and maintenance on the social infrastructure facilities we have been trying to improve the soft clayey ground using the existing methods such as the pre-loading method and the vertical drain method. Like this, when various ground improvement methods are applied on the soft clayey ground, a long-term consolidation settlement will be key issue due to low permeability coefficient of cohesive soil. According to existing research results that relate to the consolidation settlement, the loading periods for existing the standard consolidation test (Oedometer test) to obtain the consolidation parameters are needed for minimum ten days or more. Therefore, in this study, the standard consolidation test (24 hours step-loading) and constant strain rate consolidation test changed by strain rate was performed using the remolded marine clay on Gwangyang bay composed of a soft clayey ground of the south-west coast. From the laboratory test results, the characteristics of compression, strain-effective stress relations by constant strain rate and the variation characteristic of the pore water pressure by different of loading speed and the relation between consolidation parameters and constant strain rate are compared and analyzed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제23권7호
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• pp.545-549
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• 2010

Low-frequency noise (1/f noise) has been measured in order to analyze the Vth instability of ZnO TFTs having two different active layer thicknesses of 40 nm and 80 nm. Under electrical stress, it was found that the TFTs with the active layer thickness of 80 nm shows smaller threshold voltage shift (${\Delta}V_{th}$) than those with thickness of 40 nm. However the ${\Delta}V_{th}$ is completely relaxed after the removal of DC stress. In order to investigate the cause of this threshold voltage instability, we accomplished the 1/f noise measurement and found that ZnO TFTs exposed the mobility fluctuation properties, in which the noise level increases as the gate bias rises and the normalized drain current noise level($S_{ID}/{I_D}^2$) of the active layer of thickness 80 nm is smaller than that of active layer thickness of thickness 40 nm. This result means that the 80 nm thickness TFTs have a smaller density of traps. This result correlated with the physical characteristics analysis performmed using XRD, which indicated that the grain size increases when the active layer thickness is made thicker. Consequently, the number of preexisting traps in the device increases with decreasing thickness of the active layer and are related closely to the $V_{th}$ instability under electrical stress.

• Journal of Chest Surgery
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• 제31권5호
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• pp.525-530
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• 1998

Thoracoscopic thoracic sympathectomy for primary palmar hyperhidrosis has been known to be effective and to have cosmetic merits compared to conventional open sympathectomy. In spite of its cosmetic advantages over thoracotomy, VATS using 5 mm or 10 mm instruments still has the problem of operative wound as well as pain on trocar sites. Recently, 2 mm thoracoscopic instruments have been used. The purpose of this study was to examine the results of thoracoscopic sympathectomy for palmar hyperhidrosis with 2 mm thoracoscopic instruments. From January 1997 to April 1997, 46 patients underwent bilateral thoracoscopic sympathectomy with 2mm instruments at Seoul National University Hospital. T-2 ganglion was carefully dissected and resected out in all patients. In one patient, the lower third of T-1 ganglion was inadvertently resected together with T-2 ganglion due to poor anatomical localization. In 4 patients who also complained of excessive axillary sweating, T-3 ganglion was resected as well. The instruments were removed without leaving any chest drain after reexpansion of the lung. Trocar sites were approximated with sterile tapes. All patients were relieved of excessive sweating in their upper extremities immediately after the operation. Nine patients(19.6%) showed incomplete reexpansion of the lung, and two of them required needle aspiration. Complications related to the surgical procedures, such as Horner's syndrome, hemothorax, and brachial plexus injury, were not detected in any cases. Most patientsdid not complaine of pain. All patients were discharged from the hospital on the day of operation. Despite a narrow operative viewfield, thoracic sympathectomy with 2 mm thoracoscopic instruments can be performed without increasing any severe complications. We recommend 2 mm instruments for thoracoscopic sympathectomy because they make as the more cosmetic, less painful, and equally effective compared to thoracoscopic sympathectomy using 5 mm or greater instruments.

• Journal of Chest Surgery
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• 제27권2호
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• pp.99-113
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• 1994

Pentastarch is a new synthetic hydroxyethyl starch similar to hetastarch. We report on the clinical comparisons the clinical efficacy and safety of 10% pentastarch in prime solutions for CPB in cardiac operations with that of 20% serum albumin. During CPB, group P [n = 20] received 500ml of 10% pentastarch and group A [n = 20] received 100ml of 20% albumin in prime solutions The postoperative time of ICU stay in group P and the day and amount of chest drain, hospital stay in group A were longer [p<0.05]. Fresh whole blood and PRBC were added only in group A and a higher amount of hartman solution was added in group A during CPB [p<0.05]. Prothrombin time was prolonged preoperatively and 2 days postoperatively in group A and 7 days postoperatively in group P [p<0.05] but there were no significant differences in bleeding time or fibrinogen level. Platelet count was higher immediately postoperatively in group A and preoperatively and 1, 2, and 7 days postoperatively in group P [p<0.05].Total protein and albumin level were higher 1 day postoperatively in group A and 2 and 7 days postoperatively in group P [p<0.05]. BUN was increased 2 days postoperatively in group A and Cr was increased 1 day postoperatively in group P [p<0.05]. CPK was higher preoperatively and 1, 2, and 7 days postoperatively in group A and plasma hemoglobin level was also higher 2 and 7 days postoperatively in group A [p<0.05]. There were no significant differences in arterial blood gas analysis but higher pO2 and lower pCO2 levels were maintained in group P and ejection fraction was higher 7 days postoperatively in group P [p<0.05]. Both groups were improved postoperatively in NYHA class and the hemodynamic parameters such as MAP, CO, CI, SV, LVSWI were well maintained in group P [p<0.05]. The amount of blood products used was higher in group A and urine output was higher immediately postoperatively in group A and 1, 2 days postoperatively in group P and the chest output was higher in group A. The complications were developed in 7 patients in group A and 5 patients in group P and mortality was not present in both groups.In conclusion, 10% pentastarch is as safe and effective as 20% albumin in prime solutions for cardiopulmonary bypass in cardiac operations.

• Horticultural Science & Technology
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• 제28권3호
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• pp.409-414
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• 2010

The first drainage time in a day was controlled for precise irrigation management with low consumption of nutrient solution in tomato perlite bag culture system by measuring water level of drained water in drainage catchment part. This method automatically adjusted the irrigation time under any condition of light, temperature and humidity, resulting in stable water content in substrates. However, it was difficult to keep the time consistent as they were set. It drained with the deviation of 20 min in the treatment in which the first drainage time was set at 10:00 and 50 min in the treatment set at 10:30. The first drainage time was not constant, but the drain occurred stably before noon in the treatment of which irrigation frequency was longer than 30 min. The drainage ratio was better balanced in all the treatments using drainage level sensors than the treatment using time clock for irrigation control. High water and fertilizer efficiencies were obtained. Although the growth, total yield and sugar content were not significantly different between the treatments, fruit weight was higher in the treatments using drainage level sensors than that using timer.

• Korean journal of food and cookery science
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• 제19권3호
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• pp.339-353
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• 2003

The rapid increase in food borne illness outbreaks in Korea has been one of the major threats to the Nation's Health. Foodservice establishments have been identified as the major place for these outbreaks, mainly due to the lack of sanitary management and sanitary facility management practices. The purposes of the study were to develop hospital foodservice facility evaluation tools, based on the general HACCP-based standards and guidelines, for hospital food service establishments, to ensure the safety of these foodservices and to reduce the risk of food home illness. The scope of this study included: 1) an assessment of the current foodservice sanitation practices and managements for 6 general hospitals, with more than 400 beds, and 3 general hospitals, with less than 400 beds; 2) the development of foodservice establishments sanitation evaluation tools and sanitation standards, based on the HACCP system. The survey data showed varied results between the hospitals surveyed. Most of the hospital foodservice operations had many problems with ventilation and the plumbing. The total dimensional mean scores for the hospitals with more than 400 beds and less than 400 beds were 31.5 and 27.0, respectively. The highest dimension scores were for the water supply facility and lighting, with the lowest for insect and rodent control and toxic materials management. The levels of the mean scores were very low, especially for the general hospitals with less than 400 beds. These low mean scores may have arisen from critical problems within the hospital foodservice operations. The most needed facility management items for improvement were: storage shelf should be spaced 6 inches from the floor and walls, the use of three compartment sinks, utility sinks and cleaning facilities, with a floor drain for cleaning mops or liquid wastes, a ventilation hood designed to prevent dripping onto food, cooking facilities should be disassembled for washing and sanitizing, a separated hand washing sink and a sanitized food board for each area should be provided, all toxic material must have warning labels attached, and be stored in an area away from food preparation under padlock. The evaluation tool consisted of 14 dimensions, with 65 check-off items. The results of this study will provide basic facilities' guidelines to regulators, or foodservice industry personnel, wishing to build, or expend, and establish an efficient flow of food. As a result, food borne illnesses will be effectively prevented, and the Nation's health will be promoted for the development of their own sanitation standards, with a checklist for the safe production of foods.