• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.485-485
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• 2012

유기발광소자는 고휘도, 넓은 시야각, 빠른 응답속도, 높은 색재현성, 좋은 유연성의 소자특성 때문에 디스플레이 제품에 많이 응용되고 연구가 활발하게 진행되고 있다. 최근에 저소비전력, 고휘도, 소형화 및 장수명의 장점을 가진 유기발광소자의 상용화가 진행되면서 차세대 디스플레이소자로서 관심을 끌게 되었다. 고분자 유기발광소자는 저분자 유기발광소자에 비해 용액 공정법으로 박막을 형성할 수 있어 제조 비용이 적게 들며 대면적 디스플레이를 제작하는데 유리하기 때문에 많은 연구가 진행되고 있다. 고분자 유기발광소자에서 저전력 소자를 위한 저전압 구동 및 전력 효율을 향상시키기 위한 연구는 대단히 중요하다. 본 연구에서는 고분자 유기발광소자의 구동 전압을 낮추기 위해서 그래핀 정공 주입층을 삽입한 고분자 유기발광소자를 화학적 진공 증착법과 용액 공정을 사용하여 제작하였다. 그래핀 정공 주입층을 삽입한 고분자 유기발광소자는 Indium-tin-oxide(ITO) 투명 전극/그래핀 정공주입층/poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT: PSS)/poly[2-methoxy, 5-(2'-ethyl-hexyloxy)-p-phenylenevinylene] (MEH-PPV) 층/lithium quinolate (Liq)/aluminium (Al) 전극의 구조를 가진다. 그래핀 정공주입층을 삽입한 고분자 유기발광소자에서 향상된 정공 주입능력을 통해 구동전압을 낮아지는 현상을 분석하기 위해서 전기적 및 광학적 특성을 조사하였다. 그래핀 정공주입층의 광학적 특성을 분석하기 위해서 빛의 투과도 측정을 한 결과 90% 이상의 값을 얻었다. 그래핀 정공 주입층이 소자에 미치는 영향을 조사하기 위하여 ITO/PEDOT:PSS소자와 ITO/그래핀 층/PEDOT:PSS 소자를 각각 제작하여 원자힘 현미경 측정을 하였다. 그래핀박막층을 삽입할 경우, 그래핀박막층을 삽입하지 않았을 때보다 표면 거칠기가 감소하는 것을 알 수 있었다. 이는 산성을 띠는 PEDOT:PSS 용액이 ITO 투명 전극을 손상시키는 것을 방지하고, 표면 거칠기를 감소시켜 누설 전류를 낮출 수 있다는 사실을 보여준다. 또한, 그래핀 박막은 높은 전기 전도도를 가지기 때문에 그래핀 정공주입층을 삽입하였을 때, 높은 전류 밀도 및 발광 휘도와 더 낮은 구동 전압을 확인할 수 있었다. 이러한 결과는 ITO와 PEDOT:PSS의 계면에서의 전공의 주입 능력을 그래핀박막층이 향상시켜 저전압, 고효율 소자를 제작할 수 있다는 것을 보여준다.

• Korean Journal of Veterinary Service
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• v.34 no.2
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• pp.111-116
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• 2011

Artificial insemination (AI) of swine is a very useful reproductive tool and that offers convenience in the Korean swine industry. Since many viruses have been reported to be excreted through boar semen, we investigated the presence of antibodies and antigens against viruses causing reproductive failure in semen of boar in 349 semen samples collected from six Korean AI centers. Viral antigens were detected by polymerase chain reaction (PCR) or reverse transcription-PCR predominantly. The results was as follows. The major reproductive failure causing factor was porcine circovirus type 2 (PCV2), followed by porcine reproductive and respiratory syndrome virus (PRRSV) ($X^2$=166.64, P<0.001). PCV2 and PRRSV, Japanese encephalitis virus (JEV), encephalomyocarditis virus (EMCV) was detected in 73 samples (20.9%), 44 samples (12.6%), 4 samples (1.1%), 3 samples (0.9%), respectively and porcine parvovirus in one sample (0.3%) Classical swine fever virus (CSFV), bovine viral diarrhea virus and Aujeszky's disease virus (ADV) were not detected. Enzyme-linked immunosorbent assay was carried out in 111 serum samples from three AI centers. In most pigs, antibodies response was showed prominently in CSFV (105 sera, 94.6%) ($X^2$=82.580, P<0.001), followed by, in PRRSV (100 sera, 90.1%), PCV2 (92 sera, 90.1%), and PPV (8 sera, 82.9%). ADV antibody was not detected. Thus, the experimental results will be used for the base data, with respect to the state of viral stillbirth in general pig farms, as well as AI centers and breeding farms in Korea.

• Journal of Gastric Cancer
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• v.17 no.2
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• pp.145-153
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• 2017

Purpose: Identification of the infrapyloric artery (IPA) type is a key component of pylorus-preserving gastrectomy. As the indocyanine green (ICG) fluorescence technique is known to help visualize blood vessels and flow during reconstruction, we speculated that this emerging technique would be helpful in identifying the IPA type. Materials and Methods: From August 2015 to February 2016, 20 patients who underwent robotic or laparoscopic gastrectomy were prospectively enrolled. After intravenous injection of approximately 3 mL of ICG (2.5 mg/mL), a near-infrared fluorescence apparatus was applied. The identified shape of the IPA was confirmed by examining the actual anatomy following infrapyloric dissection. Results: The mean interval time between ICG injection and visualization of the artery was 22.2 seconds (range, 14-30 seconds), and the mean duration of the arterial phase was 16.1 seconds (range, 9-30 seconds). The overall positive predictive value (PPV) of ICG fluorescence in identifying the IPA type was 80% (16/20). The IPA type was incorrectly predicted in four patients, all of whom were obese with a body mass index (BMI) of more than $25kg/m^2$. Conclusions: Our preliminary results indicate that intraoperative vascular imaging using the ICG fluorescence technique may be helpful for robotic or laparoscopic pylorus-preserving gastrectomy.

• Nuclear Engineering and Technology
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• v.44 no.5
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• pp.551-560
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• 2012

The Wolsong-1 (W-1) Phase-B pre-simulations were carried out in preparation for tests to be conducted for the restart of the reactor after a major refurbishment project that included replacement of the pressure tube. These pre-simulations for Wolsong-1 Phase-B differ from those in the past that were performed for the Wolsong-1,2,3,4 tests in that these tests use the WIMS/DRAGON/RFSP-IST code suite for verification of the tests and gadolinium instead of the traditional PPV/MULTICELL/RFSP code system and boron as poison in the moderator system. The use of gadolinium is deemed not to have domestically accumulated experience gained from the previous Phase-B tests. Thus, it is appropriate to conduct a study in order to gain a correct understanding and interpretation of potential differences in test results stemming from using gadolinium rather than boron. Although the calibration of the reactivity device will not be noticeably different using boron and gadolinium at a constant moderator temperature, the temperature dependency of the neutronic behavior due to the presence of gadolinium in the moderator system might be pronounced. The results of the pre-simulations using gadolinium revealed that the moderator temperature reactivity coefficients indeed showed significant differences in comparison with those with boron. In order to secure the validity of the analysis results, the newly acquired WIMS/DRAGON/RFSP-IST code suite was verified against the W-2,3,4 Phase-B test results. The results of the new code suite verifications revealed some overall improvements in accuracy; justification of the use of the code can be claimed for the validation of the W-1 Phase-B test results.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.200-200
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• 1999

^g , pp V (Poly-para phenylene vinylene) 유도체와^g , pp P(Poly-para phennylene) 유도체에 Ar, H2, N2 및 O2 등의 이온을 조사하여 PL(Photoluminescence)의 변화를 실험하였다. 각각의 전도성 고분자는 ITO9indium tin oxide)가 증착되어 있는 유리기판위에 spin coating을 하였으며 이렇게 처리된 전도성 고분자의 표면에 이온을 조사하였다. 여기에서 조사된 이온의 가속 에너지는 300eV에서 700eV까지 변화시켰고 이온 조사량은 1$\times$1013ions/cm2에서 1$\times$1017ions/cm2까지 변화시켰다. 이때 이온빔의 전류밀도는 0.2$\mu\textrm{A}$/$\textrm{cm}^2$이하로 고정하였으며 chamber내의 진공도는 $1.5\times$10-4Torr를 유지하였다. 이온 빔처리후 불안정한 고분자의 표면이 대기와 반응하는 것을 어느정도 방지하기 위해 이온 빔으로 처리된 시료를 chamber의 내부에 일정시간동안 방치하였다. Ar, H등의 이온으로 처리된 MEH-PPV의 경우는 PL의 세기가 감소하였고 이온 조사량이 1016ions/cm2 보다 클 때 PL의 세기는 급속히 감소하였다.^g , pp V와^g , pp P 유도체의 경우는 특정 이온 조사량에서 PL의 증가현상을 보였는데^g , pp P 도체중에서 P3의 경우를 보면 이온 빔 에너지가 300eV이고 이온 전류 밀도가 0.05$\mu\textrm{A}$/$\textrm{cm}^2$인 N2이온을 조사하면 이온 조사량이 1$\times$1013ions/cm2가 될 때 PL의 세기가 39%까지 증가하였다. PL의 변화에 대한 비교를 위해 이온빔으로 처리된 시료와 처리되지 않은 시료의 UV흡수스펙트럼과 IR 흡수 스펙트럼을 분석하였다. 본 실험에 사용된 모든 시료의 PL 세기는 1016ons/cm2이상의 dose에서 급격한 감소 현상을 나타내었고 PL의 최대값을 나타내는 파장의 이동은 관찰되지 않았다.

• Journal of Preventive Medicine and Public Health
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• v.43 no.3
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• pp.257-264
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• 2010

Objectives: An accurate estimation of cancer patients is the basis of epidemiological studies and health services. However in Korea, cancer patients visiting out-patient clinics are usually ruled out of such studies and so these studies are suspected of underestimating the cancer patient population. The purpose of this study is to construct a more complete, hospital-based cancer patient registry using multiple sources of medical information. Methods: We constructed a cancer patient detection algorithm using records from various sources that were obtained from both the in-patients and out-patients seen at Asan Medical Center (AMC) for any reason. The medical data from the potentially incident cancer patients was reviewed four months after first being detected by the algorithm to determine whether these patients actually did or did not have cancer. Results: Besides the traditional practice of reviewing the charts of in-patients upon their discharge, five more sources of information were added for this algorithm, i.e., pathology reports, the national severe disease registry, the reason for treatment, prescriptions of chemotherapeutic agents and radiation therapy reports. The constructed algorithm was observed to have a PPV of 87.04%. Compared to the results of traditional practice, 36.8% of registry failures were avoided using the AMC algorithm. Conclusions: To minimize loss in the cancer registry, various data sources should be utilized, and the AMC algorithm can be a successful model for this. Further research will be required in order to apply novel and innovative technology to the electronic medical records system in order to generate new signals from data that has not been previously used.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.578-592
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• 2021

This study performed to investigate the propagation characteristics of overpressure, impulse, vibration in underwater blasting. The difference between air blasting and underwater blasting is that noise and vibration propagate through water as a medium. In some cases, the noise and vibration propagates through various media (rock, water, air, etc.). In this study, the underwater blasting was simulated using AUTODYN, and the propagation characteristics of overpressure, impulse and vibration induced by blasting were analyzed. We mainly focused on the effect of mesh size on the overpressure, impulse and peak particle velocity from the underwater blasting simulation. The numerical results indicated that the overpressure and peak particle velocity tended to decrease as the mesh size increased, while the impulse increased with the mesh size. The results also indicated that the mesh dependence varied depending on the explosive charge and scaled distance.

• The Korean Journal of Nuclear Medicine
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• v.35 no.1
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• pp.61-68
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• 2001

Purpose: The C-14 urea breath test (C-14 UBT) is the most specific noninvasive method to detect Helicobacter (H) pylori infection. We investigated if the C-14 UBT can reflect the presence and degree of H. pylori detected by gastroduodenoscopic biopsies (GBx). Materials and methods: One hundred fifty patients (M:F=83:67, age $48.6{\pm}11.2$ yrs) underwent C-14 UBT, rapid urease test (CLO test) and GBx on the same day. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (137 KBq) capsule and counting was done in a liquid scintillation counter for 1 minute, and the results were classified as positive (${\geq}200dpm$), Intermediate ($50{\sim}199dpm$) or negative (<50 dpm). The results of CLO tests were classified as positive or negative according to color change. The results of GBx on giemsa stain were graded 0 (normal) to 4 (diffuse) according to the distribution of H. pylori by the Wyatt method. We compared C-14 UBT results with GBx grade as a gold standard. Results: In the assessment of the presence of H. pylori infection, the C-14 UBT global performance yielded sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 92.5%, 88.4%, 97.1%, 88.4% and 91.3%, respectively. However, the CLO test had sensitivity, specificity, PPV, NPV and accuracy of 83.2%, 81.4%, 91.8%, 81.4% and 82.7%, respectively. The quantitative values of the C-14 UBT were $45{\pm}27$ dpm in grade 0, $707{\pm}584dpm$ in grade 1, $1558{\pm}584dpm$ in grade 2, $1851{\pm}604dpm$ in grade 3, and $2719{\pm}892dpm$ in grade 4. A significant correlation (r=0.848, p<0.01) was found between C-14 UBT and the grade of distribution of H. pylori infection on GBx with giemsa stain. Conclusion: We conclude that the C-14 UBT is a highly accurate, simple and noninvasive method for the diagnosis of ongoing H. pylori infection and reflects the degree of bacterial distribution.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.3
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• pp.229-234
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• 2008

Purpose: A urea breath test (UBT) using C-14 or C-13 has been developed for identifying Helicobacter (H) pylori infection on the basis of urease production with release of labeled $CO_2$. We investigated if the C-14 and C-13 UBT have the difference to reflect the presence and degree of H. pylori infection detected by gastro-duodenoscopic biopsies (CBx) in the same patients. Materials and methods: Thirty eight patients (M:F = 28:10, age $53.4{\pm}13.0$ yrs) with upper gastrointestinal symptoms such as indigestion, gastric fullness or pain consecutively underwent C-14 UBT, GBx and C-13 UBT within one week before medications. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (37 KBq) capsule and counting was done in a liquid scintillation counter for 1 minute, and the results were classified as positive (${\ge}$ 200 dpm), intermediate (50-199 dpm) or negative (50 dpm). For the C-13 UBT, the results were classified as positive (${\ge}2.5\%_{\circ}$) or negative ($<2.5\%_{\circ}$). The results of GBx with Giemsa stain were graded 0 (normal) to 4 (diffuse) according to the distribution of H. pylori by the Wyatt method. We compared C-14 UBT and C-13 UBT results with GBx grade as a gold standard. Results: The prevalence of H. pylori infection by GBx with Giemsa stain was 25/38 (65.8%). In the assessment of the presence of H. pylori infection, the C-14 UBT global performance yielded sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 92.0%, 92.3%, 95.8%, 91.7% and 92.1%, respectively. However, the C-13 UBT had sensitivity, specificity, PPV, NPV and accuracy of 96.0%, 84.6%, 92.3%, 91.7% and 92.1%, respectively. The more significant correlation in C-14 than C-13 UBT (r=0.948 vs r=0.819, p <0.001) was found between the value of UBT and the grade of distribution of H. pylori infection. Conclusion: We conclude that the diagnostic performance between C-14 and C-13 UBT to detect H. pylori infection is not significantly different, but the value of C-14 UBT more significantly reflects the degree of bacterial distribution.

• The Korean Journal of Nuclear Medicine
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• v.32 no.6
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• pp.497-508
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• 1998

Purpose: Using rest T1-201/dipyridamole stress gated Tc-99m-MIBI/ 24 hour delay T1-201 SPECT, we investigated the predictive values of the markers of the stress-rest reversibility (Rev), T1-201 rest perfusion (Rest), T1-201 24 hour redistribution (Del) and Tc-99m-MIBI gated systolic thickening (Thk) for wall motion improvement after coronary artery bypass surgery. Materials and Methods: In 39 patients (M;F= 34:5, age $58{\pm}8$), preoperative and postoperative (3 months) SPECT were compared. 24 hour delayed SPECT was done in 16 patients having perfusion defects at rest. Perfusion or wall motion was scored from 0 to 3 (0: normal to 3: defect or dyskinesia). Wall motion was abnormal in 142 segments among 585 segments of 99 artery territories which were surgically revascularized. Results: After bypass surgery, ejection fraction increased from $37.8{\pm}9.0%$ to $45.5{\pm}12.3%$ in 22 patients who had decreased ejection fraction preoperatively. Wall motion improved in 103 (72.5%) segments among 142 dysfunctional segments. Positive predictive values (PPV) of Rev, Rest, Del, and Thk were 83%, 76%, 43%, and 69% respectively. Negative predictive values (NPV) of Rev, Rest, Del, and Thk were 48%, 44%, 58%, and 21%, respectively. Rest/gated stress/delay SPECT had PPV of 74% and NPV of 46%. Though univariate logistic regression analysis revealed Rev (p=0.0008) and Rest (p=0.024) as significant predictors, stepwise multivariate test found Rev as the only good predictor (p=0.0008). Conclusion: Among independent predictors obtained by rest T1-201/ stress gated Tc-99m-MIBI/ delayed T1-201 myocardial SPECT for wall motion improvement after bypass surgery, stress-rest reversibility was the single most useful predictor.