• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.56.2-56.2
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• 2010

국부적 후면 전극(LBC)형성은 결정질 실리콘 태양전지에서 고효율과 저가화를 동시에 달성할 수 있는 기술이다. 후면 표면 passivation과 국부적 후면 전극 형성을 통해서 후면 재결합 속도를 낮출 수 있고 이를 통해 효율향상을 기대해볼 수 있다. 본 연구에서는 PECVD를 이용한 LBC(local back contact) cell의 후면 passivation 박막을 형성하였고 접합면적에 따른 전기적 특성을 분석해 보았다. LBC cell을 위한 후면 passivation 박막은 PECVD를 이용한 ONO박막을 사용하였고, 후면 opening 형성에 etching paste를 이용하였다. Opening size는 0.4mm,0.5mm,0.7mm로 형성하여 cell을 제작하고 효율을 분석하였다. 실험결과 opening size가 0.4mm일때 전극의 접촉면적이 15.96%, 0.5mm일때 10.22%, 0.7mm일때 5.17%로 형성됨을 확인할 수 있었다. Opening size가 0.4mm일 때 cell의 효율이 가장 우수함을 IQE 및 LIV 결과를 통해 확인 할 수 있었다. 결과적으로 접촉면적이 증가함에 따라 전극에서 수집되는 carrier의 양이 증가하고 셀 효율역시 향상됨을 확인 할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.122.2-122.2
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• 2011

결정질 태양전지 제작에서, passavtion은 표면의 반사도를 줄여주는 반사 방지막의 역할과 표면의 dangling bond를 감소시켜, 표면 재결합 속도를 줄이고 minority carrier lifetime을 증가하는 데 큰 영향을 미친다. 그렇기 때문에 저가형 고효율 태양전지 제작에서 우수한 특성을 가지는 passivation막은 매우 중요한 이슈이다. 본 연구에서는 LBC(local back contact) 구조를 가지는 단결정 태양전지 후면에, 기존의 Full Al-BSF의 passivation 막을 SiNx와 ONO passivation 막으로 각각 대체하여, LBC 구조에서 더 적합한 passivation 막을 찾고자 하였다. SiNx와 ONO passivation 막은 단결정 LBC 구조 태양전지 후면에 각각 형성되었고 $800^{\circ}C$, 20 sec 조건으로 소성되었다. 실험결과는 minority carrier lifetime과 surface recombination velocity로 관찰하였다. 그 결과, SiNx passivation 막의 표면 재결합 속도는 29.7cm/s이고, ONO passivation 막의 표면 재결합 속도는 24.5cm/s로, Full Al-BSF 표면 재결합 속도 750cm/s에 비해 더 적합한 passivation 막으로 확인할 수 있었다. 결과적으로 SiNx,ONO passivation 막이 Full Al-BSF보다 전극에 수집되는 캐리어의 양이 많아짐에 따라 효율향상을 가져올 수 있을 것이다.

• The Korean Journal of Cytopathology
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• v.17 no.1
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• pp.38-45
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• 2006

Bile duct brush cytology has been employed as a diagnostic tool for the evaluation of pancreatic and biliary tract strictures. The specificity of this method is high however, its sensitivity is quite low. A recent study employing liquid based cytology (LBC) reported results comparable to those achieved via conventional cytology. Therefore, we have attempted to prospectively evaluate the diagnostic utility of bile duct brush cytology in pancreaticobiliary diseases. A total of 46 cases with bile duct stricture were enrolled including 11 cases of benign stricture, 29 cases of bile duct carcinoma, 3 cases of gallbladder cancer, and 3 cases of pancreatic cancer. Both conventional smear and LBC using $MonoPrep2^{TM}$ system were conducted in each case. The cytological diagnosis of each case was classed into the following categories; benign, suspicious for malignancy, and malignancy. The diagnostic accuracy of both cytologic methods was investigated. LBC evidenced a high rate of material insufficiency (13/46), which was attributed to low cellularity. The kappa index of both cytological methods was 0.508. Cytological and tissue diagnoses were correlated in 25 cases conducted from biopsy or operation. The sensitivity, specificity, positive predictive value, and negative predictive value were 41.2% (7/17), 100% (8/8), 100% (7/7), and 44.4% (10/18) in conventional smear; 58.8% (10/17), 87.5% (7/8), 90.9% (10/11), and 50.0% (7/14) in LBC; and 94.1% (16/17), 87.5% (7/8), 94.1% (16/17), and 87.5% (7/8) in any one of both cytological methods, respectively. Based on these results, the sensitivity of LBC was found to be superior to that of conventional smear and we were able to obtain higher positive predictive value upto 94.1% by simultaneously conducting both cytologic methods.

• The Korean Journal of Cytopathology
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• v.18 no.2
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• pp.143-152
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• 2007

Sono-guided fine needle aspiration (FNA) of the thyroid is widely used, but the aspirated samples are typically not well preserved and low cellularity makes diagnosis difficult in many cases. The object of the current study is to evaluate the adequacy and diagnostic accuracy of the use of $SurePath^{TM}$ liquid-based cytology (SP-LBC) in the sonoguided fine needle aspiration of the thyroid nodule and to compare its use with that of the use of a conventional smear (CS). A total of 172 sono-guided FNAs of thyroid nodules from April to June, 2006 were prepared by the use of the split method with either SP-LBC or CS; the samples were stained with the use of hematoxylin-eosin (H&E) and Papanicolaou (Pap) stains. A cyto-histological correlation was performed in 69 (30 SP and 39 CS) cases that had been histologically confirmed. The rate of producing unsatisfactory slides by the use of the SP-LBC method (9.3%) was less than that of the use of the CS method (20.9%). The diagnostic accuracy of the SP method (93.3%) was better than that of the CS method (85.3%). The sensitivity and specificity of the SP method (94.4% and 92.3%) was better than that of the CS method (83.3% and 70%), respectively (p < 0.05). The CS of sono-guided aspirated specimens had some unavoidable limitations related to inadequate sampling such as a bloody background, low cellularity and an indication that some clinicians smeared many useless slides (averaging four to ten slides), and that most slides showed only blood that included few follicular cells. The SP method resulted in more thinly smeared slides and showed cleaner background and greater cellularity than the use of the CS method. Each follicular cell shows superior nuclear detail, and more distinct cytoplasmic features than with the use of the CS method. SP-LBC appears to be an easy, highly accurate, and reliable cytological method for employ for a diagnostic approach of thyroid disease and thyroid nodules. The SP-LBC method is a suitable alternative to the CS method to overcome diagnostic difficulties.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.603-603
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• 2012

최근에 전면 emitter의 doping profile이 다른 selective emitter solar cell은 실제 제작시단파장 영역에서 많은 gain을 얻을 수 없어 LBC 구조의 태양전지에 관한 연구가 많이 진행되고 있다. 본 연구는 TCAD simulation을 이용하여 후면에 형성되는 locally doped BSF(p++) region의 doping profile의 변화에 따른 태양전지 특성에 관한 연구이다. Al으로 형성되는 local back contact의 doping depth 및 surface concentration에 따른 전기적, 광학적 분석을 통해 주도적인 인자를 분석하고 최적화하였다. 특히 doping depth에 따른 변화보다는 surface concentration의 변화에 따른 특성변화가 주도적으로 나타났다.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3029-3035
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• 2013

Background: Most developing countries have been unable to implement well-organized health care systems, especially comprehensive Pap smear screening-based programs. One of the reasons for this is regional differences in medical services, and a low-cost portable cervical screening system is necessary. To improve regional discrepancies in cervical screening systems, we investigated the usefulness and acceptability of cervical selfsampling by liquid-based cytology (LBC) for 290 volunteers in the Lao PDR. Materials and Methods: Following health education with comprehensive documents, cervical self-sampling kits by LBC were distributed in three provincial, district, and village areas to a total of 290 volunteers, who were asked to take cytology samples by themselves. Subsequently, the acceptability of self-sampling was evaluated using a questionnaire. Results: The documents were well understood in all three regions. Regarding the acceptability of self-sampling, the selections for subsequent screening were 62% self-sampling, 36% gynecologist-sampling, 1% either method, and 1% other methods. The acceptability rates were higher in the district and the village than in the province. For the relationship between acceptability and pregnancy, the self-sampling selection rate was higher in the pregnancy-experienced group (75%) than in the pregnancy-inexperienced group (60%). For the relationship between selection of self-sampling and experience of screening, the self-sampling selection rate was higher in the screening-inexperienced group (62%) than in the screening-experienced group (52%). Conclusions: Our data show that this new way forward, involving a combination of self-sampling and LBC, is highly acceptable regardless of age, educational background, and residence in rural areas in a developing country.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.3
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• pp.132-139
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• 2015

Recently, $p16^{INK4a}$/Ki-67 dual immunostaining has been introduced as a new biomarker protocol for early detection of uterine cervical dysplasia and cancer in liquid-based cytology (LBC). We performed the $p16^{INK4a}$/Ki-67 dual immunostaining using a CINtec$^{(R)}$ PLUS kit in a total of 109 LBC cases of cervicovaginal smear and compared its results with those from LBC, HPV hybrid capture II (HC II) test and histological diagnosis. Expression of $p16^{INK4a}$ and Ki-67 was significantly associated with cases of LSIL or higher in cytological diagnosis and cases of cervical intraepithelial neoplasia (CIN) 1 or higher in histological diagnosis (p<0.001 and p<0.001, respectively). Among forty-six cases of atypical squamous cells of undetermined significance (ASCUS) in LBC, $p16^{INK4a}$ and Ki-67 was expressed in 31 (67.4%), which were positively associated with cases of CIN I lesion or higher in histology. The sensitivity of $p16^{INK4a}$/Ki-67 dual immunostaining for finding lesions of CIN 1 or higher was 89.0%, which was higher than LBC. The specificity was 73.5%, which was higher than that of the HC II test. Based on these results, the $p16^{INK4a}$/Ki-67 dual immunostaining method can be a useful diagnostic marker for improving the sensitivity of LBC and the specificity of HC II test.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.759-765
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• 2016

Background: Breast cancer is the most frequent cancer of women in Pakistan with the majority presenting with stage III or IV lesionsat initial diagnosis. Patient and health system related factors are well known determinants of delay in presentation and diagnosis. Additionally, breast cancer being a heterogeneous disease, the various molecular subtypes featuring different aggressiveness also need to be considered. The present study evaluated the association of stage at initial diagnosis of breast cancer with these two factors in local women at a tertiary level health care facility in Lahore, Pakistan. Materials and Methods: Patient and tumor features were recorded separately during diagnostic workup in Breast Clinics at INMOL and at Services Hospital, Lahore. Data were entered in MS Excel and analyzed by descriptive statistics and Chi-Square test. Results: Among the 261 patients, 64% were staged as late breast cancer (LBC), the mean age was 46.8 with standard deviation of 13 years. Some 92% had invasive ductal carcinoma (IDC), 61% had luminal types (LT) of non-aggressive tumor while 39% had the non-luminal types (NLT) of of HER2-enriched or basal aggressive tumors. While 70% of patients presented within one year of symptomatic disease (early report group "ERG"), 30% reported after a mean delay of 4 years with a standard deviation of 3.75 years. The stage distribution among ERG patients was not statistically different from those reporting late (P=0.123). Statistically larger proportion of patients with NLT presented as LBC as compared to the LT (P =0.034). Among the ERG, statistically different stage distribution of disease was observed for the NLT versus LT (P=0.047). Among those presenting late, this difference was insignificant (P=0.416). Conclusions: Breast cancer is a distinct disease in Pakistan with a high frequency of aggressive molecular types affecting younger women, with the majority presenting as LBC. Association of NLT with higher stage at diagnosis is statistically significant whereas time delay in diagnosis is not. Further research is required to define the risk profile and features in local patients. The burden of LBC can be reduced by promoting breast health awareness and by establishing easily accessible dedicated breast care set ups in the hospitals.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.5
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• pp.2051-2055
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• 2014

Background: To evaluate the performance of Siriraj liquid-based cytology (LBC) for cervical neoplasia screening after increasing use of this technology. Materials and Methods: Cytological reports of 103,057 Siriraj-LBC specimens obtained in 2007-2009 were compared with those of 23,676 specimens obtained in 2006. Results: Comparing with the year 2006, the 2007-2009 patients were slightly older ($43.4{\pm}12.yr$ vs $42.7{\pm}12.2yr$, p <0.001), and their specimens had much lower proportion of unsatisfactory slides (OR=0.06, 95%CI 0.04-0.09) with comparable detection rates (3.96% vs 3.70%, p=0.052) but different proportions of various cytological abnormalities (p<0.001). The 2007-2009 Siriraj-LBC had a negative predictive value (NPV) for cervical intraepithelial neoplasia 2+ (CIN2+) of 97.6% and an overall positive predictive value (PPV) of 43.9%. The PPV for CIN2+ varied with types of abnormal cytology, from 13.7% to 93.8% in atypical squamous cells of undetermined significance (ASCUS), low-grade squamous intraepithelial lesion (LSIL), atypical squamous cells cannot exclude HSIL (ASC-H), high-grade squamous intraepithelial lesion (HSIL), atypical glandular cells (AGC), to squamous cell carcinoma (SCC), respectively. The PPVs for CIN2+ in ASCUS and LSIL were comparable, but the PPV for CIN1 was higher for LSIL than for ASCUS (41.63% vs 16.32%). Conclusions: Siriraj-LBC has demonstrated a stable detection rate and NPV for CIN2+ of >95% since the first year of use. The comparable PPVs for CIN2+ of ASCUS and LSIL suggests that these two conditions may undergo similar management; other cytological abnormalities need immediate evaluation.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.55.2-55.2
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• 2010

최근 태양전지에 대한 연구가 본격적으로 진행 중인 가운데 Local back contact 태양전지에 대한 연구가 새로운 이슈로 떠오르고 있다. LBC 구조의 태양전지는 후면 passivation에 대한 최적화 공정이 가장 중요하다. 후면 passivation으로 사용되는 물질로는 $SiO_2$, SiNx, $Al_2O_3$ 등의 산화막이 대표적이다. 본 연구에서는 LBC 구조 태양전지의 후면 passivation 박막으로 사용되는 $SiO_2$ 산화막의 공정가변에 따른 박막의 특성을 비교 분석하였다. $SiO_2$ 성장은 RTP를 사용하였다. 성장 온도 $850^{\circ}C$의 온도에서 진행하였으며, 4L/min의 $O_2$분위기에서 진행하였다. 공정 시간 5분 일 때 12.5nm, 15분 일 때 21.7nm의 두께의 박막을 성장 시킬 수 있었다. Carrier lifetime 확인 결과 박막의 두께가 얇을수록 lifetime이 향상함을 확인 할 수 있었고, C-V 측정을 통한 charge 비교를 통해 두께가 얇은 박막 일수록 더 적은 positive charge를 갖고있는 것을 확인 할 수 있었으며 이를 통해 passivation 효과가 우수함을 확인 할 수 있었다.