• 한국지열·수열에너지학회논문집
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• 제10권1호
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• pp.7-13
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• 2014

This study intends to analyse the economical aspect of a GSHP(Ground Source Heat Pump) system compared to the conventional system which is consisted with a boiler and a chiller. This study has simulated four systems in Incheon. It developed and analyzed for applications in a residential and an office building which was based on the hourly EPI(Energy Performance Index, $kWh/m^2yr$). Case 1 is utilizing a boiler and a chiller to meet heating and cooling demand of a house. Case 2 is utilizing the same conventional set up as Case 1 of a office. Case 3 is summation of Case 1(house) and 2(office) systems and loads. And Case 4 is utilizing a GSHP to meet the combined loads of the house and office. The method of the economic assessment has been based on IEA ECBCS Annex 54 Subtask-C SPB(Simple Payback) method. The SPB calculated the economic balanced year of the alternative system over the reference system. The SPB of the alternative systems (GSHP) with 10%, 30% and 50% initial incentive has been calculated as 9.38, 6.72 and 4.06 year respectively while the SPB without initial incentive of systems was 10.71 year.

• 대한의용생체공학회:의공학회지
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• 제40권5호
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• pp.143-150
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• 2019

To evaluate the toxicity of ophthalmic drug, the Draize test and Bovine Corneal Opacity and Permeability (BCOP) test commonly used. In Draize test, experimental animals were under stress and pain due to long-term exposure of drug. In addition, regarding physiological functions, animal model is not perfectly reflected a human eye condition. Although some models such as $EpiOcular^{TM}$, HCE model, LabCyte Cornea-Model, and MCTT $HCE^{TM}$ were already presented advanced cornea ex-vivo model to replace animal test. In this sense, cornea tissue structure mimicked ex-vivo toxicity model was fabricated in this study. The corneal epithelial cells (CECs) and keratocytes (CKs) isolated from rabbit eyeball were seeded on non-patterned silk film (n-pSF) and patterned silk film (pSF) at $32,500cells/cm^2$ and $6,500cells/cm^2$. Sequentially, n-pSF and pSF were stacked to mimic a multi-layered stroma structure. The thickness of films was about $15.63{\mu}m$ and the distance of patterns was about $3{\mu}m$. H&E stain was performed to confirm the cell proliferation on silk film. F-actin of CKs was also stained with Phalloidin to observe the cytoskeletal alignment along with patterns of the pSF. In the results, CECs and CKs were shown the good cell attachment on the n-pSF and pSFs. Proliferated cells expressed the specific phenotype of cornea epithelium and stroma. In conclusion, we successfully established the ex-vivo cornea toxicity model to replace the eye irritation tests. In further study, we will set up the human ex-vivo cornea toxicity model and then will evaluate the drug screening efficacy.

• 한국양식학회지
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• 제18권1호
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• pp.26-30
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• 2005

본 연구는 부상 건조사료와 습사료의 효능을 비교함과 동시에 이들 사료의 적정 공급률(만복 및 제한 공급)을 조사하기 위해 수행되었다 평균 체중 27 g의 넙치를 각 수조마다 500 마리씩 2반복으로 수용하여 부상 건조사료(EP1과 EP2)와 넙치용 분말사료(우성 사료)와 냉동 전갱이를 1:3의 무게 비율(습중량 기준)로 혼합하여 성형한 moist pellet (MP)을 만복 및 만복의 $85\%$로 공급하면서 10주간 사육하였다. 생존율은 모든 실험구에서 $94\%$ 이상이었으며, 증중량은 EP2를 만복 공급한 실험구가 가장 높았지만, EP1을 만복 공급한 실험구와 MP를 만복 및 제한 공급한 실험구들과는 유의한 차이가 없었다(P>0.05). 사료효율은 EPI과 EP2를 제한으로 공급한 실험구가 가장 높은 결과를 보였으며(P<0.05),동일한 사료 공급률에 있어 MP를 공급한 실험구가 EP1과 EP2를 공급한 실험구에 비해 유의적으로 낮은 결과를 보였다(P<0.05). 일일사료섭취율은 만복 및 제한 공급구 각각에서 MP를 공급한 실험구가 EP1 및 EP2을 공급한 실험구보다 유의하게 높았다(P<0.05). 단백질효율은 만복 및 제한 공급에 관계없이 MP를 공급한 실험구가 EPI 및 EP2를 공급한 실험구보다 유의하게 낮았다(P<0.05). 에너지 축적효율은 사료종류 및 공급률에 영향을 받지 않았다(P>0.05). 전어체의 수분, 단백질 및 회분의 함량은 모든 실험구에서 유의적인 차이를 보이지 않았다. 반면에 지질의 함량은 EP2와 MP의 만복 공급구에서 가장 높았고, EP1의 만복 공급구에서 가장 낮은 값을 보였다. 본 실험의 결과로부터, 본 연구에 사용된 EP 사료들은 현재 양식현장에서 사용하고 있는 생사료를 대체할 수 있을 것으로 생각되며, 사료는 만복으로 공급되는 것이 좋을 것으로 판단된다.

• 대한방사선기술학회지:방사선기술과학
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• 제35권3호
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• pp.249-254
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• 2012

본 논문은 유방암 환자의 접선 조사 시, 치료 전 수행하는 electronic portal image와 치료 계획용 2-D reconstruction image를 비교하는 방법으로 자세의 정확성을 평가하고자 한다. 방사선 치료 중 접선조사(tangential breast treatment)만을 받는 22명의 유방암 환자를 대상으로 자세 정렬의 정확성을 확인 하였다. electronic portal image와 치료 계획용 2-D reconstruction image의 해부학적 기준 매개 변수를 비교하여 그 오차 도를 평가 하였다. 접선조사 환자의 44매 2-D reconstruction image와 110매의 EPID image 상의 비교 기준 매개 변수는 치료 조사면 중심부(field center)의 폐 길이, CLD(central lung distance), 치료 조사면 중심부의 연부조직 길이, CSTD(central soft tissue distance), 상부 총 폐 길이, ALD (above lung distance), 하부 총 폐 길이, BLD(below lung distance)이며, 내측 접선조사면(medial tangential field)에서 각 매개 변수의 오차 평균값은 1.0, -6.4, -2.1, 2.0, 각각의 표준편차(${\sigma}$)는 1.5, 2.3, 4.1, 1.1 이다. 외측 접선조사면(lateral tangential field)의 각 매개 변수 오차 평균값은 -1.5, -4.3, -2.7, -1.3 이며, 각각의 표준편차(${\sigma}$)는 3.3, 2.1, 2.9, 그리고 2.5로 나타났다. 접선조사 치료를 받는 유방암 환자의 EPID image 상에서 CLD, CSTD, ALD 그리고 BLD의 인식은 매우 용이하며 이를 근거로 자세 정렬 오차를 판단하는 것이 시간과 숙련도의 단축을 이끌어 낼 수 있다고 사료된다.

• 한국양식학회지
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• 제18권2호
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• pp.98-106
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• 2005

본 연구는 지질과 단백질 함량이 다른 두 종류 부상사료의 적정 공급횟수와 공급율을 조사하기 위해 평균 체중 55.1 g의 넙치를 각 수조마다 20마리씩 3반복으로 수용하여 58일 동안 사육하였다. 사료공급휫수는 1일 3회, 1일 2회 및 1일 1회로 설정하였으며 사료 공급량은 만복 및 만복의 80%로 각각 설정하였다. 생존율은 모든 실험 구에서 82% 이상이였으며, 평균 증중량은 EP1의 1일 2회 만복 공급구가 가장 높은 증중량을 보였으며, EP1의 1일 2회 및 3회 제한 공급구와 EP2의 1일 2회 제한 공급구가 가장 낮았다. 일일사료섭취율은 EP1의 1일 2회와 1일 3회 만복 공급구가 가장 높았고, EP2의 1일 3회 만복 공급구와 유의한 차이가 없었다(P>0.05). 사료효율과 단백질효율은 사료 조성, 공급횟수 및 공급을 모두 영향을 받지 않았다(P>0.05). 사육실험 종료시, 근육의 수분 함량은 동일한 사료와 공급휫수에서 제한 공급구가 만복 공급구에 비해 높았다. 이상의 결과들로 보아 평균체중 $55{\sim}90g$인 넙치의 성장을 위해 EP1과 EP2를 1일 2회 만복으로 공급하는 것이 적합할 것으로 판단된다.

• 한국재료학회지
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• 제33권12호
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• pp.525-529
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• 2023

β-Ga₂O₃ has become the focus of considerable attention as an ultra-wide bandgap semiconductor following the successful development of bulk single crystals using the melt growth method. Accordingly, homoepitaxy studies, where the interface between the substrate and the epilayer is not problematic, have become mainstream and many results have been published. However, because the cost of homo-substrates is high, research is still mainly at the laboratory level and has not yet been scaled up to commercialization. To overcome this problem, many researchers are trying to grow high quality Ga₂O₃ epilayers on hetero-substrates. We used diluted SiH4 gas to control the doping concentration during the heteroepitaxial growth of β-Ga₂O₃ on c-plane sapphire using metal organic chemical vapor deposition (MOCVD). Despite the high level of defect density inside the grown β-Ga₂O₃ epilayer due to the aggregation of random rotated domains, the carrier concentration could be controlled from 1 × 10¹⁹ to 1 × 10¹⁶ cm^-3 by diluting the SiH4 gas concentration. This study indicates that β-Ga₂O₃ hetero-epitaxy has similar potential to homo-epitaxy and is expected to accelerate the commercialization of β-Ga₂O₃ applications with the advantage of low substrate cost.

• 한국농공학회지
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• 제26권1호
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• pp.52-72
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• 1984

This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.