• 한국산업융합학회 논문집
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• 제26권2_2호
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• pp.285-291
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• 2023

In this paper, in order to secure the safety and productivity of pine cone harvest, modeling and structural analysis of the hammering system for pine cone harvest drone that can easily access pine cone of Pinus koraiensis and collide with them to harvest them was performed. It calculate the equivalent stress for the structure of the hammering system and the yield strength of the applied material by applying the shear force of the stalk at which the pine cone is separated from the branch, and it is to verify the safety of the structure and propose an optimal design through appropriate factor of safety and design change. The shear force of the stalk at which the pine cone was separated from the branch was 468 N, and was applied to both ends of the hammering system. The yield strength of SS400 steel used in the hammering system is 245 ㎫, and the design change and structural analysis were performed so that the Von Mises stress could be less than 122.5 ㎫ by applying the factor of safety of 2.0 or more. As a result of the structural analysis of the frist modeling, the Von Mises stress was 220.3 ㎫, the factor of safety was 1.12, and the stress was concentrated in the screw fastening holes. As a result of the design change of the screw fastening holes, the Von Mises stress was 169.4 ㎫, the factor of safety was 1.45, and the stress was concentrated on the side part. As a result of the design change by changing screw fastening holes and adding ribs, the Von Mises stress was 121.6 ㎫, and the factor of safety was 2.02. The safety of the hammering system was secured with an optimal design with little change in mass. There was no deformation or damage as a result of experimenting on pine cone harvest by manufacturing the hammering system with an optimal design.

• 한국분무공학회지
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• 제28권1호
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• pp.16-23
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• 2023

The objective of this numerical study is to investigate the effect of the shape and material of the blower blade for the electrified speed sprayer on the blowing performance. The shape of the blade was changed to the bonding angle, the number of blades, the width of the blade, and the blade length based on the existing model. In order to obtain the reliability of the numerical model, the analysis of the grid dependence was performed in the numerical analysis. The numerical analysis results were compared and analyzed in terms of the agricultural chemical penetration length characteristics, flow uniformity characteristics, and velocity distribution characteristics. Furthermore, the effect of material change on weight reduction and structural characteristics was also compared and analyzed. As a result of the analysis, it was found that the optimal condition was that the blade angle was 45°, the number of blades was 12, and the width was 115 mm, which was confirmed through a comparison of the inlet mass flow rate. As a result of the equivalent stress lower than the yield strength due to the material change from aluminum to steel compared to the existing steel, structural defects do not appear, and it is judged that the operation time compared to the battery capacity will be improved through the weight reduction of the blade.

• 한국해양생명과학회지
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• 제2권2호
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• pp.83-89
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• 2017

In abalones, interspecific hybridization has been suggested as a possible means to increase production and desired traits for the industry. In Korea, Haliotis gigantea is considered a species with a larger size and higher temperature tolerance than H. discus hannai. However, H. discus hannai is considered the most valuable and popular fishery resource due to its better acceptance and higher market prices. Thus, viable interspecific hybrids have been produced by artificial inseminating H. gigantea eggs with H. discus hannai sperm. However, the reciprocal hybrid cross was not successful. In this study, the hybridity and the growth and thermal tolerance performance of the interspecific hybrids were examined. A combination of various assays revealed maximum growth occurrence at 21℃ and the higher growth rate in the hybrids than that of H. discus hannai parent. In addition, the growth and survival at high-temperature (28℃) of the hybrids was equivalent to that of the highly tolerant H. gigantea parent, suggesting new possibilities to overcome the mass mortality in H. discus hannai during high temperature periods of summer season in Korea. Furthermore, the induced interspecific hybrid status was confirmed by the presence of species-specific bands for each parental species of the random amplified polymorphic DNA (RAPD) profiles using universal rice primer (URP), which could be used as speciesspecific markers to distinguish the hybrids and their parental species.

• Restorative Dentistry and Endodontics
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• 제45권4호
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• pp.45.1-45.8
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• 2020

Objective: The aim of this study was to introduce a gelatin/bovine serum albumin (BSA) tissue standard, which provides dissolution properties identical to those of biological tissues. Further, the study evaluated whether the utilization of endodontic activating devices led to enhanced phantom dissolution rates. Materials and Methods: Bovine pulp tissue was obtained to determine a benchmark of tissue dissolution. The surface area and mass of samples were held constant while the ratio of gelatin and BSA were varied, ranging from 7.5% to 10% gelatin and 5% BSA. Each sample was placed in an individual test tube that was filled with an appropriate sodium hypochlorite solution for 1, 3, and 5 minutes, and then removed from the solution, blotted dry, and weighed again. The remaining tissue was calculated as the percent of initial tissue to determine the tissue dissolution rate. A radiopaque agent (sodium diatrizoate) and a fluorescent dye (methylene blue) were added to the phantom to allow easy quantification of phantom dissolution in a canal block model when activated using ultrasonic (EndoUltra) or sonic (EndoActivator) energy. Results: The 9% gelatin + 5% BSA phantom showed statistically equivalent dissolution to bovine pulp tissue at all time intervals. Furthermore, the EndoUltra yielded significantly more phantom dissolution in the canal block than the EndoActivator or syringe irrigation. Conclusions: Our phantom is comparable to biological tissue in terms of tissue dissolution and could be utilized for in vitro tests due to its injectability and detectability.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.449-457
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• 2023

본 연구에서는 철근의 부식에 대한 콘크리트의 구조적 한계를 실험적으로 정의하였다. 구조적 한계는 (1) 항복 시 콘크리트의 변형, (2) 최대 부착강도, (3) 부식되지 않은 시험체 수준의 부착강도로 고려하였다. 철근 표면에서 전하를 추출하는 전기화학적 방식을 이용하여 철근 부식을 촉진시켰다. 그 결과, 철근 직경이 증가할수록 부식 정도가 증가하여 콘크리트 변형은 항복상태에 도달하는 것으로 나타났다. 또한 철근 직경의 증가는 최대 부착강도와 부식되지 않은 수준의 부착강도에 도달되기 위한 전류 인가량을 증가시켰다. 그러나 질량 손실은 철근 크기에 미미하게 영향을 받았는데, 이는 구조적 성능의 매개변수(콘크리트 변형, 부착강도의 변화)를 통해 철근 부식에 의한 구조물의 사용수명을 대변할 수 있음을 의미한다.

• Journal of Radiation Protection and Research
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• 제48권4호
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• pp.184-196
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• 2023

Background: Radiation protection is crucial in various fields due to the harmful effects of radiation. Shielding is used to reduce radiation exposure, but gamma radiation poses challenges due to its high energy and penetration capabilities. Materials and Methods: This work investigates the radiation shielding properties of polyvinylidene fluoride (PVDF) samples containing different weight fraction of tungsten carbide (WC), tungsten trioxide (WO₃), and tungsten disulfide (WS₂). Parameters such as the mass attenuation coefficient (MAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), and macroscopic effective removal cross-section for fast neutrons (Σ_R) were calculated using the Phy-X/PSD software. EpiXS simulations were conducted for MAC validation. Results and Discussion: Increasing the weight fraction of the additives resulted in higher MAC values, indicating improved radiation shielding. PVDF-xWC showed the highest percentage increase in MAC values. MFP results indicated that PVDF-0.20WC has the lowest values, suggesting superior shielding properties compared to PVDF-0.20WO₃ and PVDF-0.20WS₂. PVDF-0.20WC also exhibited the highest Z_eff values, while PVDF-0.20WS₂ showed a slightly higher increase in Z_eff at energies of 0.662 and 1.333 MeV. PVDF-0.20WC has demonstrated the highest Σ_R value, indicating effective shielding against fast neutrons, while PVDF-0.20WS₂ had the lowest Σ_R value. The Monte Carlo N-Particle Transport version 5 (MCNP5) simulations showed that PVDF-xWC attenuates gamma radiation more than pure PVDF, significantly decreasing the dose equivalent rate. Conclusion: Overall, this research provides insights into the radiation shielding properties of PVDF mixtures, with PVDF-xWC showing the most promising results.

• Journal of Chest Surgery
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• 제56권6호
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• pp.403-411
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• 2023

Background: The concept of oligo-recurrence has not been generally applied in esophageal cancer. This study aimed to determine the prognostic significance of the number of recurrences in esophageal cancer. Methods: Patients with squamous cell carcinoma who underwent curative esophagectomy with R0 or R1 resection and who experienced a confirmed recurrence were included. The study included 321 eligible participants from March 2001 to December 2019. The relationship between the number of recurrences and post-recurrence survival was investigated. Results: The mean age was 63.8±8.1 years, and the majority of the participants (97.5%) were men. The median time to recurrence was 10.7 months, and the median survival time after recurrence was 8.8 months. Multiple recurrences with simultaneous local, regional, and distant locations were common (38%). In terms of the number of recurrences, single recurrences were the most common (38.3%) and had the best post-recurrence survival rate (median, 17.1 months; p<0.001). Patients with 2 or 3 recurrences showed equivalent survival to each other and longer survival than those with 4 or more (median, 9.4 months; p<0.001). In the multivariable analysis, the significant predictors of post-recurrence survival were body mass index, minimally invasive esophagectomy, N stage, R0 resection, post-recurrence treatment, and the number of recurrences (p<0.05). Conclusion: After esophagectomy, the number of recurrences was the most significant risk factor influencing post-recurrence survival in patients with esophageal cancer. In esophageal cancer, oligo-recurrence can be defined as a recurrence with three or fewer metastases. More intensive treatment might be recommended if oligo-recurrence occurs.

• 센서학회지
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• 제33권1호
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• pp.24-29
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• 2024

Inkjet printing technology is used to mass-produce displays and electrochemical sensors by dropping tens of pico-liters or less of specific-purpose ink through nozzles, just as ink is sprayed and printed on paper. Unlike the deposition method for vaporizing material in a vacuum, inkjet printing technology can be used for processing even under general atmospheric pressure and has a cost advantage because the material is dissolved in a solvent and used in the form of ink. In addition, because it can only be printed on the desired part, masks are not required. However, a technical shortcoming is the difficulty for commercialization, such as uniformity for forming the thickness and coffee ring effect. As sizes of devices decrease, the need to print electrodes with precision, thinness, and uniformity increases. In this study, we improved the printing and processing conditions to form a homogeneous electrode using Ag ink (DGP-45LT-15C) and applied this for patterning to fabricate a heat sensor. Upon the application of voltage to the heat sensor, the model with an extended width exhibited superior heat performance. However, in terms of sheet resistance, the model yielded an equivalent value of 21.6 Ω/□ compared to the ITO.

• 한국양식학회지
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• 제14권3호
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• pp.197-203
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• 2001

이 연구는 치어기 틸라피아에 있어서 어분(fish meal, FM) 대체 단백질원으로서 라이신 부산물(lysine cell mass, LCM)이 사료내 이용 가능성과 대체 수준을 결정하기 위해 수행하였다 실험사료는 조단백질 35%, 가용성 에너지 15.3 kJ/kg으로 설계되었고, 주 단백질원으로 어분, 대두박, 콘글루텐밀 및 라이신 부산물을 사용하였다. 주 동물성 단백질원인 어분 단백질을 라이신 부산물에 의한 대체 수준에 따라 사료 조성을 요약하면 다음과 같다: $LCM_0, 100% FM: LCM_{10}, 90% FM+10% LCM, LCM_{20}, 80% FM+20% LCM; LCM_{30}, 70% FM+30% LCM; LCM_{40}, 60% FM+40% LCM; LCM_{30}l, 70% FM+30% LCM+lysine; LCM_{30}ln, 70% FM +30% LCM + lysine +NaOH; LCM_{40}lan, 60% FM+40% LCM+lysine+arginine; LCM_{40}/lan, 60% FM+40% LCM+lysine+arginine+NaOH.$ 8주간의 실험 결과, 증체율과 일간성장률에 있어서는 사료구 $LCM_0$와 비교하여 모든 사료구에서는 유의적인 차이가 없었으며, 아울러 아미노산 첨가 및 중화효과는 모든 사료구에서 나타나지 않았다(p>0.05). 사료효율과 단백질 전환효율에 있어서 사료구 LCMo는 사료구 $LCM_{10}. LCM_{20}. LCM_{30}lan, LCM_{40}lan 및 LCM_{40}lan$과 비교하여 유의적인 차이를 보이지 않은 반면에(P>0.05), 사료구 $LCM_{30}, LCM_{40} 및 LCM_{30}l$보다 유의적으로 높게 나타났다(P<0.05). 아미노산 첨가와 중화효과에 있어서 사료구 $LCM_P{30}la, LCM_{30}l 및 LCM_{30}ln$은 유의적인 차이가 나타나지 않은 반면에 사료구 $LCM_{40}la 및 CM_{40}lan은 LCM_{40}$과 비교하여 유의적으로 높게 나타났다(P<0.05). 따라서, 치어기 틸라피아에 있어서 성장을 기준으로 라이신 부산물은 어분 단백질을 40%까지 대체가 가능하였으며, 아울러 높은 라이신 부산물의 대체 수준에 있어서 사료효율과 단백질 전환효율을 고려한다면 아미노산 첨가(라이신과 아르지닌)와 중화 효과에 좋은 결과가 있을 것으로 사료된다.

• 한국수산과학회지
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• 제35권4호
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• pp.336-341
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• 2002

본 연구는 치어기 잉어에 있어서 어분 (fish meal, FM) 대체 단백질원으로서 lysine 부산물 (lysine cell mass, LCM)이 사료내 이용 가능성과 대체 수준을 결정하기 위해 수행하였다. 실험사료의 조단백질 함량은 $38\%$, 가용에너지는 15.2kJ/g (protein, carbohydrate and lipid: 16.7, 16.7 and 37.7kJ/g)으로 동일하게 맞추어 실험사료를 제조하였으며, 사료의 조성을 요약하면 다음과 같다: $100\%$ $FM; LCM_20$, $80\%$ $FM+20\%$ $LCM; LCM_40$, $60\%$ $FM+40\%$ $LCM; LCM_60$, $40\%$ $FM+60\%$ $LCM; LCM_100$, $100\%$ $LCM; LCM_20$l, $80\%$ $FM+20\%$ $LCM+0.07\%$ $Lysine; LCM_40$l, $60\%$ $FM+40\%$ $LCM+0.14\%$ $Lysine; LCM_60$l $40\%$ $FM+60\%$ $LCM+0.22\%$ $Lysine; LCM_100$l, $100\%$ $LCM+0.35\% Lysine. 6주 동안의 실험 결과, 증체율, 사료효율, 일간성장률, 간중량지수 및 단백질전환효율에 있어서 LCM_0와 비교하석 LCM_20는 유의적인 차이가 없는 반면에 (P>0.05), $LCM_40,\;LCM_60$ 및 $LCM_100,\;LCM_40l,\;LCM_60$l 및 $LCM_100$l는 유의적으로 낮게 나타났다 (P<0.05). $LCM_0$와 $LCM_20$l은 증체율, 일간성장률, 간중량지수 및 단백질 전환효율에 있어서는 유의적인 차이를 보이지 않는 반면에 (P>0.05), 사료효율에 있어서는 $LCM_0$에 비해 $LCM_20$l이 유의적으로 낮게 나타났다 (P<0.05). 헤마토그리트과 비만도는 모든 사료구에서 유의적인 차이가 없었다 (P<0.05). 따라서, 치어기 잉어에 있어서 Iysine 부산물은 어분단백질의 $100\%$ $FM; LCM_20$, $80\%$ $FM+20\%$ $LCM; LCM_40$, $60\%$ $FM+40\%$ $LCM; LCM_60$, $40\%$ $FM+60\%$ $LCM; LCM_100$, $100\%$ $LCM; LCM_20$l, $80\%$ $FM+20\%$ $LCM+0.07\%$ $Lysine; LCM_40$l, $60\%$ $FM+40\%$ $LCM+0.14\%$ $Lysine; LCM_60$l $40\%$ $FM+60\%$ $LCM+0.22\%$ $Lysine; LCM_100$l, $100\%$ $LCM+20\%까지 대체 가능하며, lysine 부산물에 결핍된 필수아미노산인 lysine을 첨가한 사료구에서는 첨가 효과가 나타나지 않았다.