• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.626-626
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• 2013

P-N 접합에 의해 절연된 게이트를 통해 전류 통로를 제어하는 접합형 전계효과 트랜지스터(Junction Field Effect Transistors; JFETs)는, 입력 임피던스가 크고, 온도에 덜 민감하며, 제조가 간편하여 집적회로(IC) 제조가 용이하고, 동작의 해석이 단순하다는 장점을 가지고 있다. 특히 JFET는 선형적인 전류의 증폭 특성을 가지고 있으며, 잡음이작기 때문에, 감도가 우수한 음향 센서의 증폭회로, 선형성이 우수한 증폭회로, 입력 계측 증폭 회로 등에 주로 사용되고 있다. 기존에 사용되는 JFET 소자는 구조와 제조 공정에 따라서, 컷 오프 전압($V_{cut-off}$)과 드레인-소스 포화 전류($I_{DSS}$)의 변화가 심하게 발생하여, 소자의 전기적 특성 제어가 어렵고, 소자의 수율이 낮다는 문제점이 있다. 본 연구에서는 TCAD 시뮬레이션을 통해 게이트 전압에 의해 채널이 형성되는 채널 층의 상하부에 각각 $Si_xGe_{1-x}$로 이루어진 상부 및 하부 확산 저지층을 삽입한 JFET 소자 형성하여, 게이트 접합부의 접합 영역 확산을 저지하고, 상기 게이트 접합부가 계면에서 날카로운 농도 구배를 갖도록 함으로써, 공정 변화에 따른 전기적 특성의 편차가 작아지는 JFET 소자 구조를 만들어 전기적 특성을 개선하였다. JFET은 채널층에 삽입된 $Si_xGe_{1-x}$ 층의 두께, Ge 함유량 및 n채널층의 두께를 변화하였을 때, off 상태의 게이트-소스 전압이 감소한 반면에 드레인-소스 포화 전류($I_{DSS}$)와 컨덕턴스(gm) 값이 증가하였다. 삽입된 $Si_xGe_{1-x}$층이 Boron이 밖으로 확산되는 현상이 감소하여 채널이 좁아지는 현상을 막아 소자의 전기적 특성을 개선함으로써 제조공정의 변화에 관계없이 컷오프 전압을 정확하고 안정되게 제어할 수 있고 이를 통해 소자의 수율을 높일 수 있을 것으로 기대된다.

• 한국지반공학회지:지반
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• 제14권5호
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• pp.191-204
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• 1998

플라이 애쉬의 폐기물 매립장 대용 차수재로서의 적용성을 평가하기 위하여 실내 실험과 모델 연구를 실시하였다. 실제의 매립장 차수층이 불포화 상태일 수 있는 점을 고려하여, 대용 차수재와 기존의 점토 차수재에서의 포화 및 불포화 상태에서의 물 흐름 특성을 비교하였다. 차수층에서의 오염물 이동 특성을 연구하기 위하여 오염물을 이용한 회분실험을 실시하였으며, 이때 폐놀을 대표 오염물질로 사용하였다. 모델은 물질 수지에 기초하였으며, 유한 차분법과 predictor-corrector법을 이용한 수치 해법으로 풀었고, 연립 미분방정식을 다루는테는 sequential method를 이용했다. 연구 결과 대용 차수재는 기존 차수재보다 폐놀 차단 능력이 더 크고 또 불포화대에서의 차수능력도 더 크다는 것을 알 수 있었다. 또한, 본 연구에서 고려된 흐름조건에서는 차수층을 포화대로 해석할 경우 통과하는 물의 양이 약간 과소평가되고 폐놀 차단 능력은 매우 과소평가됨을 알 수 있었다.

• 한국자기학회지
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• 제15권5호
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• pp.270-275
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• 2005

가스분무법으로 제조한 $35\~180\;{\mu}m$ 크기의 $Fe-6.0wt\%Si$ 합금분말에 대하여 인산염계 절연물질을 피막처리하고 $600\~900^{\circ}C$에서 1시간 동안 열처리한 후 압축성형한 압분자심(분말코아)의 자기적 성질 및 기계적 특성을 조사하였다. 대체적으로 열처리온도가 증가할수록 압축강도가 감소하였으며, 자심손실 또한 낮아졌다. $800^{\circ}C$에서 열처리한 경우 압축성형강도가 15 kgf, 100 kHz에서 실효투자율은 74, 품질계수는 26, 50 Oe의 직류자장 하에서 퍼센트투자율은 78 정도의 값을 나타내었으며, 50 kHz-0.1 T에서 자심손실은 $750\;mW/cm^3$였다. 그리고 투자율-주파수 곡선 상에서의 cut-off 주파수는 거의 200 kHz 이상에 이르는 것으로 나타났다. $Fe-6.0wt\%Si$ 합금 압분자심의 이러한 제반 특성은 인산염 피막의 양호한 전기절연효과와, 고규소농도에 따른 합금의 결정자기이방성 및 포화자기변형의 감소, 전기비저항의 증대 등 기초 물성의 변화에 기인하는 것으로 사료되었다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제43권5호
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• pp.305-311
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• 2017

Objectives: TNM staging, especially for lymph node metastasis, is the scoring system most widely used among prognostic factors for cancer survival. Several biomarkers have been studied as serologic markers, but their specificity is low and clinical applications are difficult. This study aimed to establish a scoring system for patients with oral squamous cell carcinoma (OSCC) using platelet (PLT) and mean platelet volume (MPV) levels measured postoperatively and to evaluate their significance as prognostic factors. Materials and Methods: We studied 40 patients admitted to the Department of Oral and Maxillofacial Surgery of Dankook University Hospital who were diagnosed with primary OSCC histopathologically between May 2006 and May 2012. Clinical pathological information obtained from the medical records of each patient included age, sex, height, weight, tumor location, degree of differentiation, tumor diameter, lymph node metastasis, TNM stage, and other test values including white blood cell, MPV, PLT, C-reactive protein (CRP), and albumin obtained through a test conducted within 7 days before surgery. Count of platelet (COP)-MPV Score: Patients with both PLT and MPV values below the cut-off values were defined as score 0 (group A). Patients with at least one of the two higher than the cut-off value were defined as score 1 (group B). Results: Univariate analyses showed N-metastasis, COP-MPV (A vs B), PLT, platelet-lymphocyte ratio, and CRP were statistically significant prognostic factors. A multivariate Cox proportional hazards model showed N-metastasis (hazard ratio [HR] 6.227, P=0.016) and COP-MPV (A vs B) (HR 18.992, P=0.013) were independent prognostic factors with a significant effect on survival. Conclusion: COP-MPV score is a simple and cost-effective test method and is considered a more effective prognostic factor than other considered factors in predicting the prognosis of OSCC patients.

• 한국축산식품학회지
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• 제33권3호
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• pp.369-376
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• 2013

Milk is well known to be rich in some nutrients such as protein, calcium, phosphorus, and vitamins. In particular, absorption and bioavailability of calcium receive lots of attention because calcium is very little absorbed until it is changed to the ionized form in the intestine. In this study, concentration of the soluble calcium was determined in the commercial bovine milk products, which were processed by different heat-treatment methods for pasteurization. As for general constituents, lactose, fat, protein, and mineral were almost same in the liquid milk products by different processors. Ultrafiltration of the skimmed milk caused little change in the permeate as for lactose content but both fat and protein decreased. pH values ranges from 6.57-6.62 at room temperature and slightly increase after centrifugation, 10,000 g, 10 min. Rennet-coagulation activity was the lowest in the ultra high temperature (UHT-)milk compared to the low temperature long time (LTLT-) and high temperature short time (HTST-)milk products. Each bovine milk products contains 1056.5-1111.3 mg/kg of Ca. The content of sulfhydryl group was the lowest in raw milk compared to the commercial products tested. For the skimmed milks after ultrafiltration with a membrane (Mw cut-off, 3 Kd), soluble Ca in the raw milk was highest at 450.2 mg/kg, followed by LTLT-milk 336.4-345.1 mg/kg, HTST-milk 305.5-313.3 mg/kg, UHT-milk 370.3-380.2 mg/kg in the decreasing order. After secondary ultrafiltration with a membrane (Mw cut-off, 1 kD), total calcium in raw milk had a highest of 444.2 mg/kg, and those in the market milk products. As follow: UHT-milk, 371.3 to 378.2 mg/kg; LTLT-milk, 333.3 to 342.2 mg/kg; HTST-milk 301.9 to 311.2 mg/kg in a decreasing order.

• 한국재료학회지
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• 제17권8호
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• pp.447-451
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• 2007

We investigated the dependence of the various annealing conditions and thickness ($6\sim45nm$) of the Ti-doped $Al_2O_3$ coating on the electrochemical properties and the capacity fading of Ti-doped $Al_2O_3$ coated $LiCoO_2$ films. The Ti-doped-$Al_2O_3$-coating layer and the cathode films were deposited on $Al_2O_3$ plate substrates by RF-magnetron sputter. Microstructural and electrochemical properties of Ti-doped-$Al_2O_3$-coated $LiCoO_2$ films were investigated by transmission electron microscopy (TEM) and a dc four-point probe method, respectively. The cycling performance of Ti-doped $Al_2O_3$ coated $LiCoO_2$ film was improved at higher cut-off voltage. But it has different electrochemical properties with various annealing conditions. They were related on the microstructure, surface morphology and the interface condition. Suppression of Li-ion migration is dominant at the coating thickness >24.nm during charge/discharge processes. It is due to the electrochemically passive nature of the Ti-doped $Al_2O_3$ films. The sample be made up of Ti-doped $Al_2O_3$ coated on annealed $LiCoO_2$ film with additional annealing at $400^{\circ}C$ had good adhesion between coating layer and cathode films. This sample showed the best capacity retention of $\sim92%$ with a charge cut off of 4.5 V after 50 cycles. The Ti-doped $Al_2O_3$ film was an amorphous phase and it has a higher electrical conductivity than that of the $Al_2O_3$ film. Therefore, the Ti-doped $Al_2O_3$ coated improved the cycle performance and the capacity retention at high voltage (4.5 V) of $LiCoO_2$ films.

• 한국방사선학회논문지
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• 제17권3호
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• pp.465-472
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• 2023

본 연구는 혈관질환을 예측하는 데 있어서 일차 선별검사로서 경동맥 초음파 검사와 혈액학적 검사를 실시한 환자를 대상으로 경동맥 내중막 두께의 변화를 확인하고 죽상경화반의 발현에 위험인자들이 미치는 영향을 알아보고자 하였다. 일개 병원에서 건강검진을 목적으로 내원하여 경동맥 초음파 검사를 실시한 건강한 성인 469명을 대상으로 후향적으로 분석하였다. 그 결과 경동맥 내중막 두께, 연령, 체질량지수, 허리둘레, 수축기 혈압, 총콜레스테롤, 고비중지단백 콜레스테롤, 저비중지단백 콜레스테롤, 공복혈당이 죽상경화반의 유의한 예측인자로 분석되었다(p<0.001). ROC curve 분석을 통해 결정된 죽상경화반 위험인자들의 Cut off value를 기준으로 위험비를 산출하였으며 경동맥 내중막 두께는 8.06배, 연령은 7.53배, 허리둘레는 3.97배, 공복혈당은 2.02배 순으로 높게 나타났다. 따라서 본 연구에서는 죽상경화반의 유무에 영향을 주는 임상학적 위험요인들의 한국인 기준치를 마련할 수 있었으며, 초음파를 이용한 경동맥의 관찰은 심뇌혈관 질환을 조기에 진단하거나 예측하는데 도움이 될 것으로 생각된다.

• Architectural research
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• 제19권2호
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• pp.45-52
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• 2017

Recently, as a new perspective to view the architecture in relation to global environmental problems, interest in environmental architecture that conforms to the surrounding environment and nature with nature has been expanded as a part of the natural ecosystem, rather than seeing the building as an independent entity. Traditional Korean architecture creates a comfortable indoor environment by appropriately using the natural energy around, ranging from the arrangement of the building and the space composition to the use of detailed materials and to harmonize the artificial architectural environment without harming the natural ecosystem. The purpose of this study is to propose a method to apply the environmental control techniques of traditional buildings to modern buildings. As a research method, the characteristics of Korean traditional buildings according to the climatic characteristics of Korea were recognized through existing literature data and when applied to methods of traditional buildings, ventilation systems, control through eaves, and humidity control using Hanji the effect of energy load control on traditional buildings was analyzed and identified through existing literature. After analyzing the problems of modern architecture, we analyzed the effect of the environmental control system of traditional architecture on modern architecture. Simulation results show that the application of the environmental control system of traditional buildings to modern buildings reduces the cooling and heating load of modern buildings and has an effect on humidity control. This study suggests that quantitative energy saving will be possible if the environmental control techniques of traditional buildings are appropriately applied to modern buildings.

• 한국환경과학회지
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• 제17권1호
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• pp.113-118
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• 2008

[ $6{\sim}13mg/L$ ] base water concentration on monthly BOD has been kept at the Geukrak bridge point for this research target and it indicates the water quality under the existed rank. Due to this present condition of water quality, the demage of ecology from the upper stream to the lower one of the bridge could be conjectured. Moreover, nonstructural extinction of the ecology seems to have gotten worse between both the streams of Yeoungsan River. On this research, eco-corridor between the upper stream and the lower stream of the river should be ensured, the ecological demage needs to be cut off, a dispersed discharge method which the existed method of the 1st sewage plant in Gwangju was enhanced to should be inducted for the procuring of various water ecosystem, and the conditions by the scenario suggested from this research could be applied to a water quality model. then, analysis the improvement effect of the water quality adjacent the river. From the test result, Case3-Type1 scenario is thought to be the best one. From the test result with Case3-Type1 when the concentrated discharge was never done, 0.07 mg/L of BOD concentration was increased at the lower stream where Yeoungbon B point (Haksan Bridge) is but the water improvement effect of $0.24{\sim}2.87mg/L$ is thought to have been done at the area of water deterioration.

• The Korean Journal of Pain
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• 제30권4호
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• pp.296-303
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• 2017

Background: To achieve a prolonged therapeutic effect in patients with lumbar facet joint syndrome, radiofrequency medial branch neurotomy (RF-MB) is commonly performed. The purpose of this study was to evaluate the prognostic value of paravertebral muscle twitching when performing RF-MB in patients with lumbar facet joint syndrome. Methods: We collected and analyzed data from 68 patients with confirmed facet joint syndrome. Sensory stimulation was performed at 50 Hz with a 0.5 V cut-off value. Patients were divided into 3 groups according to the twitching of the paravertebral muscle during 2 Hz motor stimulation: 'Complete', when twitching was observed at all needles; 'Partial', when twitching was present at 1 or 2 needles; and 'None', when no twitching was observed. The relationship between the long-term effects of RF-MB and paravertebral muscle twitching was analyzed. Results: The mean effect duration of RF-MB was 4.6, 5.8, and 7.0 months in the None, Partial, and Complete groups, respectively (P = 0.47). Although the mean effect duration of RF-MB did not increase significantly in proportion to the paravertebral muscle twitching, the Complete group had prolonged effect duration (> 6 months) than the None group in subgroup analysis. (P = 0.03). Conclusions: Paravertebral muscle twitching while performing lumbar RF-MB may be a reliable predictor of long-term efficacy when sensory provocation under 0.5 V is achieved. However, further investigation may be necessary for clarifying its clinical significance.