• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.236-245
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• 2000

The feasibility of precision farming for small sized fields was studied by determining fertilizing amount of nitrogenous and calcareous to a cite specific region. A detailed soil survey at three experimental fields of 672㎡, 300㎡ and 140㎡ revealed a considerable spatial variation of the pH and organic matter(OM) levels. Soil organic matter was measured using Walkley-Black method and soil pH was measured with a pH sensor. Soil sample was obtained by Grid Node Sampling Method. The soil sampling depth was 10 - 20 cm from the soil surface. To display soil nutrient variation, a soil map was made using Geographic Information System (GIS) software. In soil mapping, soil data between nodes was interpolated using Inverse Distance Weighting (IDW) method. The variation was about 1 - 1.8 in pH value and 1.4 -7 % in OM content. Fertilizing Amount of nitrogenous and calcareous was determined by the fertilizing equation which was proposed by National Institute of Agricultural Science and Technology.(NIAST). The variation of fertilizing amount was about 3 - 11 kg/10a in nitrogenous and 70 - 140 kg/10a in calcareous. The results showed a feasibility of precision fertilizing for small size fields.

• 한국재료학회지
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• 제19권8호
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• pp.417-420
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• 2009

This study develops a highly transparent ohmic contact using phosphorus doped ZnO with current spreading for p-GaN to increase the optical output power of nitride-based light-emitting diodes (LEDs). The phosphorus doped ZnO transparent ohmic contact layer was prepared by radio frequency magnetron sputtering with post-deposition annealing. The transmittance of the phosphorus doped ZnO exceeds 90% in the region of 440 nm to 500 nm. The specific contact resistance of the phosphorus doped ZnO on p-GaN was determined to be $7.82{\times}10^{-3}{\Omega}{\cdot}cm^2$ after annealing at $700^{\circ}C$. GaN LED chips with dimensions of $300\times300{\mu}m$ fabricated with the phosphorus doped ZnO transparent ohmic contact were developed and produced a 2.7 V increase in forward voltage under a nominal forward current of 20 mA compared to GaN LED with Ni/Au Ohmic contact. However, the output power increased by 25% at the injection current of 20 mA compared to GaN LED with the Ni/Au contact scheme.

• 한국재료학회지
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• 제19권8호
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• pp.443-446
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• 2009

This study develops a highly transparent ohmic contact scheme using indium oxide doped ZnO (IZO) as a current spreading layer for p-GaN in order to increase the optical output power of nitride-based lightemitting diodes (LEDs). IZO based contact layers of IZO, Ni/IZO, and NiO/IZO were prepared by e-beam evaporation, followed by a post-deposition annealing. The transmittances of the IZO based contact layers were in excess of 80% throughout the visible region of the spectrum. Specific contact resistances of $3.4\times10^{-4}$, $1.2\times10^{-4}$, $9.2\times0^{-5}$, and $3.6\times10^{-5}{\Omega}{\cdot}cm^2$ for IZO, Ni/Au, Ni/IZO, and NiO/IZO, respectively were obtained. The forward voltage and the optical output power of GaN LED with a NiO/IZO ohmic contact was 0.15 V lower and was increased by 38.9%, respectively, at a forward current of 20 mA compared to that of a standard GaN LED with an Ni/Au ohmic contact due to its high transparency, low contact resistance, and uniform current spreading.

• 대한금속재료학회지
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• 제46권1호
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• pp.26-32
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• 2008

Examination of two bronze vessels supposedly from the Koryo dynasty revealed that they consist of bowls and stands that are fixed together using rivet joints made of Cu-Ag alloys. The bowls and stands were forged out of unleaded bronze alloys of approximately 22 weight % Sn before being quenched from the ${\alpha}+{\beta}$ region of the Cu-Sn phase diagram. This specific alloy and the thermo-mechanical treatment constitute two key elements of the unique technical tradition called Bangcha (방짜) that has long been established in Korea. The high Sn content ensures better casting and the thermal treatment causes the brittle ${\delta}$ phase to be avoided in forging as well as in services. The experiment on the laboratory Cu-Ag alloys of varying Ag contents suggested that the Cu-Ag system was the best choice of materials for the rivets at the time in view of their color, availability, ductility and low melting points.

• 한국전기전자재료학회논문지
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• 제37권3호
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• pp.332-336
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• 2024

High-energy bandgap material silicon carbide (SiC) is gaining attention as a next-generation power semiconductor material, and in particular, SiC-based MOSFETs are developed as representative power semiconductors to increase the breakdown voltage (BV) of conventional planar structures. However, as the size of SJ (Super Junction) MOSFET devices decreases and the depth of pillars increases, it becomes challenging to uniformly form the doping concentration of pillars. Therefore, a structure with different doping concentrations segmented within the pillar is being researched. Using Silvaco TCAD simulation, a SJ VVD (vertical variation doping profile) MOSFET with three different doping concentrations in the pillar was studied. Simulations were conducted for the width of the pillar and the doping concentration of N-epi, revealing that as the width of the pillar increases, the depletion region widens, leading to an increase in on-specific resistance (R_on,sp) and breakdown voltage (BV). Additionally, as the doping concentration of N-epi increases, the number of carriers increases, and the depletion region narrows, resulting in a decrease in R_on,sp and BV. The optimized SJ VVD MOSFET exhibits a very high figure of merit (BFOM) of 13,400 KW/cm², indicating excellent performance characteristics and suggesting its potential as a next-generation highperformance power device suitable for practical applications.

• 대한금속재료학회지
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• 제48권6호
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• pp.565-569
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• 2010

We report on the characteristics of indium-oxide-doped ZnO (IZO) ohmic contact to p-GaN. The IZO ohmic contact layer was deposited on p-GaN by a Roll-to-Roll (RTR) sputter method. IZO contact film with a thickness of 360, 230 and 100 nm yielded an ohmic contact resistance of $4.70{\times}10^{-4}$, $5.95{\times}10^{-2}$, $4.85{\times}10^{-1}\;{\Omega}cm^{2}$ on p-GaN when annealed at $600{^{\circ}C}$ for 1 min under a nitrogen ambient, respectively. While the transmittance of IZO film with a thickness of 360 nm slightly increased in the wavelength range of 380-800 nm after annealing, the transmittance rapidly increased up to 80% after annealing at $600{^{\circ}C}$ in the wavelength range of 380~430 nm because the crystallization of IZO film and created Ga vacancies near the p-GaN surface region were affected by the annealing. These results indicate that ohmic contact resistance and transmittance of the IZO films improved.

• Journal of Genetic Medicine
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• 제7권2호
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• pp.133-137
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• 2010

목 적: Beckwith-Wiedemann 증후군(BWS)은 11p15 부위의 메칠화 양상의 이상으로 인한 overgrowth malformation symdrome이다. 11p15 부위에는 두 가지 imprinting center, 즉BWSIC1 (IGF2, H19)와 BWSIC2 (LIT1,KvDMR)가 존재한다. 본 연구에서는 methylation-specific (MS) PCR RFLP 방법을 이용한 BWS의 유전적 진단을 보고하고자 한다. 대상 및 방법: 임상 소견을 바탕으로 12명의 BWS 환자가 포함되었다. 환자의 말초혈액으로부터 염색체 핵형을 조사하였다. 분리한 DNA에 bisulfite를 처리한 후, LIT1, H19, IGF2 DMR부위는 각각의 MS primer를 이용하여 증폭하였다. 적절한 제한효소를 이용하여 절단 여부를 PAGE로 확인함으로써 각각의 DMR 부위에 대한 메칠화 이상 여부를 확인하였다. 결 과: 12명의 환자는 모두 정상 핵형을 보였다. MS-PCR RFLP 상 총 7명(53.8%)의 환자가 이상 소견을 보였으며, 모두 BWSIC2 (LIT1)에 비정상적 메칠화를 보였고 모두 부계 유래의 비메칠화된 allele만이 발견되었다. 결 론: 본 연구를통해MS-PCR RFLP 검사로BWS 환자의 약 50-60% 정도에서 유전적 진단이 가능함을 알 수 있었으며, 이는 BWSIC2 부위의 메칠화 이상을 발견하는데 손쉽게 이용될 수 있을 것으로 판단된다. 그러나, BWSIC1 부위의 메칠화 이상은 발견이 어려우며, 이 부위의 이상을 발견하기 위해서는 메칠화를 정량적으로 분석할 수 있는 방법이 필요하다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6821-6832
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• 2013

Background: Soft-tissue sarcomas require tailored and multidisciplinary treatment and management. However, little is known about how sarcomas are treated and managed throughout the Asia-Pacific region. Materials and Methods: MEDLINE was systematically searched using prespecified criteria. Publications (previous 10 years) that reported tumour characteristics, treatment patterns, survival outcomes, and/or safety outcomes of patients with soft-tissue sarcoma were selected. Exclusion criteria were studies of patients <18 years of age; ${\leq}10$ patients; countries other than Australia, Hong Kong, Indonesia, Korea, Malaysia, New Zealand, Philippines, Singapore, Taiwan, or Thailand; >20% benign tumours; sarcomas located in bones or joints; gastrointestinal stromal tumour; Kaposi's sarcoma; or not reporting relevant outcomes. Results: Of the 1,822 publications retrieved, 35 (32 studies) were included. Nearly all patients (98%, 1,992/2,024; 31 studies) were treated with surgery, and more studies used adjuvant radiotherapy than chemotherapy (24 vs 17 studies). Survival outcomes and recurrence rates varied among the studies because of the different histotypes, sites, and disease stages assessed. Only 5 studies reported safety findings. Conclusions: These findings highlight the lack of specific data available about soft-tissue sarcomas in the Asia-Pacific region. Better efforts to understand how the sarcoma is managed and treated will help improve patient outcomes in the region.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권1호
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• pp.18-26
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• 2009

Purpose: Recently, the role of serum tumor marker has been studied for an important issue on diagnosing and treating tumors in the head and neck region because tests using tumor markers need relatively simple procedures and are acceptable to patients, compared with other test methods. Tumor marker tests were performed on patients with squamous cell carcinoma, which were known to have the highest prevalence among tumors in the head and neck region. Association between each tumor marker, and diagnosis and prognosis of tumors was assessed. Materials and methods: Tumor marker tests were carried out on 31 patients who visited Oral and Maxillofacial Surgery Department in Dankook University Dental Hospital between January 2003 and August 2008 and who were diagnosed as primary oral squamous cell carcinoma through out histopathologic diagnosis. Blood sample from these patients was performed to measure tumor markers using nuclear medicine diagnostic equipment. Measured entries were as follows: PSA(prostate-specific antibody), SCCAg( Squamous Cell Carcinoma Related Antigen), CA 19-9(Cancer Antigen 19-9), Ferritin, $\alpha$- FP(Alpha-Fetoprotein), Cyfra 21-1, CA125 (Cancer Antigen 125) and p53. Results: Analyses on each tumor marker indicated that squamous cell carcinoma in the head and neck region had statistically significant correlation with p53, SCC-Ag(TA-4), Cyfra 21-1 and Ferritin. p53 demonstrated the highest sensitivity. Especially, 4 cases among 18 cases which Ferritin was measured exhibited metastasis. In all those 4 cases, Ferritin values were higher than the standards (15 - 332ng/ml). Therefore, Ferritin is considered to have a close relation with metastasis of squamous cell carcinoma. Conclusion: This study shows that tumor marker tests are more useful in evaluating progression and prognosis of tumors rather than in diagnosing them. Particularly, serum Ferritin is considered to be beneficial in assessing metastasis of squamous cell carcinoma in the head and neck region and in developing treatment plans based on the assessment.

• Asian Pacific Journal of Cancer Prevention
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• 제15권23호
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• pp.10293-10298
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• 2015

Background: Previous epidemiologic studies on the association between energy intake and endometrial cancer risk have only generated contradictory results. The role of energy intake in endometrial carcinogenesis thus remains unclear. To quantitatively assess the potential association between energy intake and endometrial cancer, a meta-analysis of case-control and cohort studies was here conducted. Materials and Methods: Eligible studies were retrieved via both computerized searches and review of references. Fixed-or random-effect models were used to summarize the estimates of OR with 95%CIs. Stratified analyses on study design, region and macronutrients' calorie were performed. Results: Sixteen studies met the inclusion criteria of the meta-analysis. No association between total energy intake and endometrial cancer was observed in either overall group (OR=1.11, 95%CI 0.92-1.30) or subgroups stratified by study design and region. In the specific macronutrients' calorie analysis, higher fat energy intake was found to be associated with increased endometrial risk (OR=1.72, 95%CI 1.12-2.32) while energy from carbohydrate and protein was not related to endometrial cancer risk. Conclusions: Our analysis did not support that total energy intake is related to endometrial cancer risk, in contrast to fat energy.