• Journal of Korean Ophthalmic Optics Society
• /
• v.21 no.3
• /
• pp.281-288
• /
• 2016

Purpose: The present study was aimed to investigate the change of optical quality in fully cured eyes from central serous chorioretionopathy(CSC) and CSC under treatment, respectively. Methods: A total of 136 eyes(68 subjects) was divided into CMC under treatment and its asymptomatic contralateral eye, fully cured eyes after being diagnosed with CMC and its contralateral eye, and normal eyes. Objective scattering index, cut-off value in modulation transfer function, focusing rate, PSF(Point Spread Function) width at 50%, 10% and the contrast sensitivity were measured and analyzed. Results: CMC under treatment showed statistically significant decrease in all evaluations of optical quality compared with asymptomatic contralateral eyes, fully cured eyes and normal eyes. Although there was no significant difference in optical quality between asymptomatic contralateral eyes of CMC under treatment and fully cured eyes, there was tendence in optical quality decreasing compared with normal eyes. Conclusions: From the study, it was revealed that the optical quality was different according to the treatment phase in CMC. The use of optical quality assessment for the decision of complete cure and the evaluation of prognosis in CMC is also proposed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.2
• /
• pp.52-59
• /
• 2008

The objective of this study is to develop an automatic object changer unit to improve processing problems existed in the conventional horizontal machining center. To achieve this goal, this study designed a horizontal transfer as the second project continued to the first project that designed a upward and downward traverse unit. A horizontal traverse unit shows a symmetric structure and consists of frame, which consists of four unit tools, motor and reducer, which are fixed at a frame, operation unit with pinions, first traverse unit, and second traverse unit. Constraint conditions based on the operation mechanism with these elements were configured and obtained following results after modeling a model for a traverse motor. In the kinematic expression of sliding motion with one degree of freedom, the sliding motion is constrained. Also, the rack 3 installed at a frame is used to configure possible kinematic constraint conditions of the rack 2 according to the rolling motion of the pinion 2 in the first traverse unit. In addition, the moment of inertia that is a type of kinetic energy in a converted horizontal traverse unit in the side of the reducer can be applied to introduce the moment of inertia of a converted horizontal traverse unit in the side of the reducer by using the sum of kinetic energy in the rack and pinion, which is a part of the horizontal traverse unit. Also, the equation of motion of the converted upward and downward traverse unit in the side of the motor using the equation of motion of the motor. Furthermore, the horizontal traverse unit predetermines the mass of the first and second traverse unit and applied load including the radius and reduction ratio of the pitch circle in the pinion 1 and applied load to the rack 2. Then, a proper motor can be determined using several parameters in the upward and downward traverse unit in order to verify such predetermined specifications. In future studies later this study, a simulation that verifies the results of the previous two stages of studies using a finite element method.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.5
• /
• pp.389-397
• /
• 2014

An absorption chiller-heater using only a natural refrigerant hardly causes any environmental pollution. In an absorption chiller-heater, the performance of its high-temperature generator, which uses exhaust gases, is essential to achieving superior system performance. To investigate the performance of such a high-temperature generator, a laboratory-scale high-temperature generator working with exhaust gases was designed and tested. Changes in the performance of the high-temperature generator as a function of inlet conditions of the absorbing solution, such as air inlet temperature and mass flow, were investigated. It was observed that when the air mass flow rate ratio was increased from 80% to 120%, the heat capacity was increased by 30%, 33%, 34%, and 37%, respectively. Additionally, when the air inlet temperature was elevated from $170^{\circ}C$ to $210^{\circ}C$ for absorption solution concentrations of 56%, 55%, 545, and 53%, the heat capacity increased by 140%, 160%, 220%, and 224%, respectively.

• Journal of the Korean Society for Library and Information Science
• /
• v.50 no.3
• /
• pp.309-327
• /
• 2016

Scholarly monographs have been a main vehicle for knowledge representation and transfer as well as an important research outcome. University presses have long been considered as the last bastion for scholarly monographs that have low commercial prospect. Until now there has not been a systematic data analysis regarding scholarly monograph production by university presses in Korea. In this paper, we collected bibliographic records of university presses' monograph publications between 1950 and 2015 using the National Library of Korea's online catalog system. A total of 21,015 records were used in the analysis. In particular, for monographs published between 2001 and 2015, we categorized them into scholarly monographs and non-scholarly monographs. University presses' publishing showed sharp increase during the 1990's but is in decline after its peak in 2005. University presses seem to have engaged in publishing more non-scholarly monographs than scholarly monographs by a ratio of 6:4. Large university presses in size seem to produce higher proportions of scholarly monographs than smaller presses. In terms of authoring types, single authorship accounts for the highest proportion and on the increase. However, edited books are losing ground as translated books seem to hold steady. Monographs in social sciences have been published more frequently than any other subject areas as there seem to be significant discrepancies among subject areas in terms of the scholarly monograph proportion.

• Journal of Animal Environmental Science
• /
• v.15 no.3
• /
• pp.241-250
• /
• 2009

This study was conducted to develop an prototype automatic feeder (AF) for growing-finishing pigs. The main components of AF were a feed storage hopper, a feeding motor, a feed agitator, a control box and a programmable IC, which were controlled by a personal computer. The powder type feed transfer rate of AF was average $9.83{\pm}0.4\;g\;s^{-1}$. In feeding test, growing pigs (Landrace) of about 43 kg live weight were used in the study, and was fed over a 6 weeks in pens with solid concrete floors. For feeding trials with AF, the operation time of the feeding motor was set to 2, 3, 4, 5, and 6 seconds per feeding. Pigs frequently used AF from 05:00 to 11:00 and from 11:00 to 17:00 without relationship to the operation time of the feeding motor. The AF operation time of the feeding motor to minimize feed loss was between 2 and 4 seconds. Pigs fed with AF had same or slightly higher average daily gam (0.8~0.9 kg) than that with a commercial feeder, and average daily feed intake (2.76~2.93 kg) and feed conversion ratio (3.10~3.66) of pigs fed with AF were same or lower than those with the commercial feeder except the operation time of the feeding motor set to 6 seconds. As a result, AF would help to use and improve the productivity of growing-finishing pigs.

• Journal of Environmental Health Sciences
• /
• v.28 no.2
• /
• pp.117-129
• /
• 2002

Concentration of welding fumes and their components is known to be hazardous to welder and adjacent worker. To determine the generation rates of metals in fumes, $CO_2$ flux cored arc welding on stainless steel was performed in well designed fume collection chamber. Variables were different products of flux cored wire(2 domestic products and 4 foreign products) and input energy(low-, optimal- , high input energy). Mass of welding fumes was determined by gravimetric method(NIOSH 0500 method), and 17 metals were analysed by inductively coupled plasm-atomic emission spectroscopy(NIOSH 7300 method). Flux cored wire tube and flux were analysed by scanning electron microscopy to determine their metal composition. 17 metals were classified by their generation rates. Generation rates of iron, manganese, potassium and sodium were all above 50mg/min at optimal input energy level. Generation rates of chromium and amorphous silica were 25~50mg/min. At 1~25mg/min level, nickel, titanium, molybdenum, and aluminum were included. Copper, zinc, calcium, lead, magnesium, lithium, and cobalt were generated below 1 mg/min. Generation rates of metal components in fumes were influenced by input energy, types of flux cored wire. Flux cored wire was consisted of outer shell tube and inner flux. Iron, chromium, and nickel were the major components of outer tube. Flux contained iron, chromium, nickel, potassium, sodium, silica, and manganese. The use of flux cored wire can increase the hazards by increasing the amounts of fumes formed relative to that of solid wire. The reason might be the direct transfer of elements from the flux, since the flux is fine power. Ratio of metals to the fume of flux cored wire was lower than that of solid wire because non-metal components of flux were transferred. Total metal content of fumes in flux cored arc welding was 47.4(24.3~57.2) percent that is much lower than that of solid wire, 75.9 percent. We found that generation rates of iron, manganese, chromium and nickel, all well known to cause work related disease to welder, increased more rapidly with increasing input energy than those of fumes. To reduce worker exposure to fumes and hazardous component at source, further research is needed to develop new welding filler materials that decrease both the amount of fumes and hazardous components.

• Journal of Radiation Protection and Research
• /
• v.25 no.4
• /
• pp.233-239
• /
• 2000

The sensitivity analysis of input parameters was Performed fer an ingestion dose assessment model (U. S. NRC's Regulatory Guide 1.109 model) from routine releases of radionuclides. In this study, three kinds of typical Korean foodstuffs (rice, leaff vegetables, milk) and two kinds of radionuclides $(^{l37}Cs,\;^{131}I)$ were considered. The values of input parameters were sampled using a Latin hypercube sampling technique based on Monte Carlo approach. Sensitivity indices, which represent the influence or the importance of input parameters for predictive results, were quantitatively expressed by the partial rank correlation coefficients. As the results, the ratio of the interception fraction to the yield of agricultural plants and the human consumption rate were sensitive input parameters for the considered foodstuffs and radionuclides. Additionally, in case of milk, the transfer factor of radionuclides from animal intake to milk and the daily intake rate of feedstuffs were sensitive input parameters. The weathering removal half-life and the delay time from food production to human consumption were relatively sensitive for $^{137}Cs$ and $^{131}I$ depositions, respectively.

• Journal of Acupuncture Research
• /
• v.33 no.4
• /
• pp.109-119
• /
• 2016

Objectives : The aim of this study is to give a statistical basis for the characteristics of patients who received cooperative medical care after being referred from Western medical departments to the Department of Acupuncture and Moxibustion in a Korean medical hospital. Methods : The request records were searched for cooperative medical treatment at the Department of Acupuncture and Moxibustion in a Korean medical hospital between September 1st, 2011 and August 31, 2016, based on the Order Communication system(OCS). The records were reviewed and retrospectively analyzed according to the patient's general characteristics, the chief diagnosis code based on the 7th Korean standard classification of diseases(KCD-7) before and after the cooperative medical care in the Department of Acupuncture and Moxibustion, and the actual treatment measures which patients received as a result of the cooperative medical care. Results : Among the 2702 records, 1549 patients were included in the analysis. The male to female ratio was 1 : 1.17. Sexagenarians formed the highest age group and the number of patients whose age was over 50 was 1176(75.92 %). The surgery department requested the cooperative care from the department of Acupuncture and Moxibustion for the highest number of patients, 1194(77.08 %). When analysing specific medical departments, Neurosurgery, General Surgery, Neurology, Otorhinolaryngology, and Physical medicine and rehabilitation followed. The frequency of chief diagnosis code used before the cooperative medical care was in the order of I, C, G, S, and M code, from highest to lowest. The order of the codes after the cooperative medical care was the same. Acupuncture treatment was the most frequently-used measure after the cooperative medical care. Following were infrared, moxibustion, transfer, herbal acupuncture, cupping, electroacupuncture, and so on. Conclusion : This study provides a statistical basis for the demands placed on the Department of Acupunture and Moxibustion for cooperative medical care with the Western medical department. Based on the present condition of cooperative medical care, more preparation and effort is required for its activation.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.53.2-53.2
• /
• 2010

지금까지 능동 구동 디스플레이의 TFT backplane에 사용하고 있는 채널 물질로는 수소화된 비정질 실리콘(a-Si:H)과 저온 폴리실리콘(low temperature poly-Si)이 대표적이다. 수소화된 비정질 실리콘은 TFT-LCD 제조에 주로 사용되는 물질로 제조 공정이 비교적 간단하고 안정적이며, 생산 비용이 낮고, 소자 간 특성이 균일하여 대면적 디스플레이 제조에 유리하다. 그러나 a-Si:H TFT의 이동도(mobility)가 1 cm2/Vs이하로 낮아 Full HD 이상의 대화면, 고해상도, 고속 동작을 요구하는 UD(ultra definition)급 디스플레이를 개발하는데 있어 한계 상황에 다다르고 있다. 또한 광 누설 전류(photo leakage current)의 발생을 억제하기 위해서 화소의 개구율(aperture ratio)을 감소시켜야하므로 패널의 투과율이 저하되고, 게이트 전극에 지속적으로 바이어스를 인가 시 TFT의 문턱전압(threshold voltage)이 열화되는 문제점을 가지고 있다. 문제점을 극복하기 위한 대안으로 근래 투명 산화물 반도체(transparent oxide semiconductor)가 많은 관심을 얻고 있다. 투명 산화물 반도체는 3 eV 이상의 높은 밴드갭(band-gap)을 가지고 있어 광 흡수도가 낮아 투명하고, 광 누설 전류의 영향이 작아 화소 설계시 유리하다. 최근 다양한 조성의 산화물 반도체들이 TFT 채널 층으로의 적용을 목적으로 활발하게 연구되고 있으며 ZnO, SnO2, In2O3, IGO(indium-gallium oxide), a-ZTO(amorphous zinc-tin-oxide), a-IZO (amorphous indium-zinc oxide), a-IGZO(amorphous indium-galliumzinc oxide) 등이 그 예이다. 이들은 상온 또는 $200^{\circ}C$ 이하의 낮은 온도에서 PLD(pulsed laser deposition)나 스퍼터링(sputtering)과 같은 물리적 기상 증착법(physical vapor deposition)으로 손쉽게 증착이 가능하다. 특히 이중에서도 a-IGZO는 비정질임에도 불구하고 이동도가 $10\;cm2/V{\cdot}s$ 정도로 a-Si:H에 비해 월등히 높은 이동도를 나타낸다. 이와 같이 a-IGZO는 비정질이 가지는 균일한 특성과 양호한 이동도로 인하여 대화면, 고속, 고화질의 평판 디스플레이용 TFT 제작에 적합하고, 뿐만 아니라 공정 온도가 낮은 장점으로 인해 플렉시블 디스플레이(flexible display)의 backplane 소재로서도 연구되고 있다. 본 실험에서는 rf sputtering을 이용하여 증착한 a-IGZO 박막에 대하여 열처리 조건 변화에 따른 a-IGZO 박막들의 광학적, 전기적 특성변화를 살펴보았고, 이와 더불어 a-IGZO 박막을 TFT에 적용하여 소자의 특성을 분석함으로써, 열처리에 따른 Transfer Curve에서의 우리가 요구하는 Threshold Voltage(Vth)의 변화를 관찰하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.9
• /
• pp.1719-1729
• /
• 1994

In this paper, an adaptive CAC(Connection Admission Control) method is proposed. The adaptive CAC uses traffic estimates derived from both traffic parameter specified by user and cell flow measurements. Traffic estimation using user-specified parameters is performed at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. Traffic estimation using cell flow measurement is carried out when the number of connected calls does not change during a measurement reflection period-renewal period. The most import ant thing for the traffic estimation using cell flow measurement is the determination of the length of a renewal period to trace a real traffic flow with an allowable time lag and the measurement reflection ratio(MRR) both to reduce the portion of overestimation and to avoid underestimation of real traffic flow. To solve these problems, the adaptive CAC updates renewal period and MRR adaptively according to the number of connections and the elapsed time after last connection or release respectively. Performance analysis for the proposed method is evaluated in several aspects for the cases of both homogeneous and heterogeneous bursty traffic. Numerical examples show the adaptive CAC method has the better performance compared with conventional CAC method based on burst model from the both utilization and QOS point of view.