• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.235-235
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• 2003

The development of a buffer layer is an important issue for the second -generation wire, YBCO coated metal wire. The buffer layer demands not only on the prohibition of the reaction between YBCO and metal substrate, but also the proper lattice match and conductivity for high critical current density (Jc) of YBCO superconductor, In order to satisfy these demands, we suggested CaRuO3 as a useful candidate having that the lattice mismatches with Ni (200) and with YBCO are 8.2% and 8.0%, respectively. The CaRuO3 thin films were deposited on Ni substrates using various methods, such as e-beam evaporation and DC and RF magnetron sputtering. These films were investigated using SEM, XRD, pole-figure and AES. In e-beam evaporation, the deposition temperature of CaRuO3 was the most important since both hi-axial texturing and NiO formation between Ni and CaRuO3 depended on it. Also, the oxygen flow rate had i[n effect on the growth of CaRuO3 on Ni substrates. The optimal conditions of crystal growth and film uniformity were 400$^{\circ}C$, 50 ㎃ and 7 ㎸ when oxygen flow rate was 70∼100sccm In RF magnetron sputtering, CaRuO3 was deposited on Ni substrates with various conditions and annealing temperatures. As a result, the conductivity of CaRuO3 thin films was dependent on CaRuO3 layer thickness and fabrication temperature. We suggested the multi-step deposition, such as two-step deposition with different temperature, to prohibit the NiO formation and to control the hi-axial texture.

• Journal of Microbiology and Biotechnology
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• 제19권7호
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• pp.718-726
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• 2009

The objective of this study was to develop and validate secondary models that can predict growth parameters of L. monocytogenes Scott A as a function of concentrations (0-3%) of a commercial potassium lactate (PL) and sodium diacetate (SDA) mixture, pH (5.5-7.0), and temperature (4-37DC). A total of 120 growth curves were fitted to the Baranyi primary model that directly estimates lag time (LT) and specific growth rate (SGR). The effects of the variables on L. monocytogenes Scott A growth kinetics were modeled by response surface analysis using quadratic and cubic polynomial models of the natural logarithm transformation of both LT and SGR. Model performance was evaluated with dependent data and independent data using the prediction bias ($B_f$) and accuracy factors ($A_f$) as well as the acceptable prediction zone method [percentage of relative errors (%RE)]. Comparison of predicted versus observed values of SGR indicated that the cubic model fits better than the quadratic model, particularly at 4 and $10^{\circ}C$. The $B_f$and $A_f$for independent SGR were 1.00 and 1.08 for the cubic model and 1.08 and 1.16 for the quadratic model, respectively. For cubic and quadratic models, the %REs for the independent SGR data were 92.6 and 85.7, respectively. Both quadratic and cubic polynomial models for SGR and LT provided acceptable predictions of L. monocytogenes Scott A growth in the matrix of conditions described in the present study. Model performance can be more accurately evaluated with $B_f$and $A_f$and % RE together.

• 한국전산구조공학회논문집
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• 제22권6호
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• pp.617-625
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• 2009

본 연구에서는 MgO를 첨가하여 자기팽창을 유도하는 화학적 프리스트레싱 기법(chemically prestressing method)으로 균열을 제어하는 방법을 다루고자 한다. 수화열에 의한 온도변형 및 수축과 같은 콘크리트의 필연적인 체적변화는 시공 중 균열을 발생시키고, 이는 장기적인 콘크리트의 내구성 및 사용성을 저하시키는 주요 요인으로 작용한다. 시공 중 발생하는 균열을 제어하기 위하여 본 연구는 MgO 콘크리트의 팽창 특성을 모델링하고 콘크리트의 단면 내 온도분포로부터 온도응력 및 자기팽창 응력을 평가하는 3차원 유한요소해석 프로그램을 개발하였다. 개발된 해석프로그램은 온도의존적 자기팽창량과 팽창응력을 검증하였고, 예제 해석을 통하여 MgO 팽창 여부에 따른 잔류응력(residual stress)의 변화 양상을 비교, 분석하였다. 저온에서 소성한 MgO를 혼입하여 제조한 장기팽창성 콘크리트는 온도의존적 특성을 보이고 수년에 걸쳐 발생하는 경향을 보이므로, 장기적으로 높은 온도가 유지되는 매스콘크리트 구조물의 온도균열을 제어하는데 가장 유용하게 적용될 수 있을 것으로 사료된다.

• 한국양식학회지
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• 제18권4호
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• pp.272-279
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• 2005

각시붕어, Rhodeus uyekii (Mori, 1935)와 칼납자루, Acheilognathus koreensis (Kim and Kim, 1990)에 대한 염산리도카인과 Clove oil의 $10^{\circ}C,\;15^{\circ}C,\;20^{\circ}C$ 및 $25^{\circ}C$ 수온 조건에서의 마취 효과를 조사하였다. 3분 미만의 완전마취(Stage A5)와 10분 미만의 완전회복(Stage R5)을 기준시, 마취 수온 $20^{\circ}C$에서의 염산리도카인 적정 농도는 각시붕어와 칼납자루에서 각각 250${\~}$550 ppm, 150${\~}$550 ppm 이었으며 Clove oil에서는 각각 40${\~}$200 ppm, 80${\~}$240 ppm 이었다. 본 실험의 2종을 대상으로 한 염산리도카인과 Clove oil에 의한 마취시 negative곡선의 농도 의존성을 보였다. 회복시간은 마취제 농도에 따라 다소 변이를 보였으나, 일반적으로 고농도 마취는 긴 회복시간을 보였다. 마취 수온과 마취 효과는 있어 양성의 상관관계가 있어, 저온에서의 마취시 마취시간과 회복시간이 더 소요되었다. 본 연구에서 사용된 어류 마취제 염산리도카인과 Clove oil은 본 실험에 사용된 종들에 효과적인 마취제임을 시사한다. 본 연구로부터의 결과는 각시붕어와 칼납자루의 사육시 어체 진정이 요구되는 취급이나, 이들의 양식시 유용할 것이다.

• 한국응용곤충학회지
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• 제51권3호
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• pp.235-243
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• 2012

중요 시설해충인 아메리카잎굴파리(Liriomyza trifolii (Burgess))의 개체군 밀도변동모형을 방울토마토 온실내 대기온도와 잎 표면온도를 이용하여 모형 정확성을 비교하였다. 모형 개발에 이용된 생물적 변수들은 기존 발표된 자료들을 사용하였고 모형 작성은 DYMEX$^{(R)}$ 프로그램을 이용하였다. 온도에 따라 상이한 발육기간과 산란수는 생리적 연령으로 표준화시킨 발육완료 분포모형, 연령 특이적 산란수 및 생존율을 비선형회귀 모형에 적합시켜 밀도변동 모형을 개발하였다. 줄내림방식의 방울토마토에서 식물체를 3개의 위치(상단: 지상 1.6 m 이상, 중단: 지상 0.9 - 1.2 m 사이, 하단: 지상 0.3 - 0.5 m 사이)로 나누고 각 위치별로 온실 내 대기 온도와 잎 표면 온도를 기록하였다. 온실 내 잎 표면 최대온도는 대기중 최대온도보다 항상 낮게 유지되고 있었으며, 하단, 상단, 중단의 순으로 온도가 낮아지는 경향을 보였다. 개발된 모형검정을 위한 초기이입 시기와 밀도는 6월초 성충 5마리가 총 50개의 알을 잎에 산란한 것으로 설정하였다. 온실 내 대기 온도와 잎 표면 온도를 이용하여 아메리카잎굴파리 유충 발육모형과 성충의 산란모형을 DYMEX로 프로그래밍하고 모의실험을 하였다. 모의실험결과를 평가하기 위해 기상자료를 수집한 동일한 온실에서 아메리카잎굴파리 유충 밀도를 육안조사 하였으나, 알, 번데기, 성충의 경우 육안조사가 어려워 대상에서 제외하였다. 육안조사결과 밀도변동패턴이 방울토마토 잎 표면 온도를 이용한 모의실험결과 밀도변동패턴과 유사하였다. 육안조사결과와 육안조사시기의 DYMEX모의실험 결과값을 상관분석 한 결과, 육안조사결과와 잎 표면 온도를 이용한 모의실험 결과가 유의한 양의 상관관계를 보였다(r = 0.97, p < 0.01). 대기 온도를 이용한 모의실험 결과와는 유의하지 않은 상관관계를 보였다(r = 0.40, p = 0.18). 본 연구결과 방울토마토 온실에서 아메리카잎굴파리 개체군 밀도변동의 적절한 예측을 위해서는 잎 표면 온도를 고려해야 하는 것으로 나타났다.

• 한국정밀공학회지
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• 제3권1호
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• pp.40-49
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• 1986

Crack, craze and void are common defects which may be found in the bulk of polymeric materials such as either themoplastics or thermosets. The healing phenomena, autohesion, of these defects are known to be a intrinsic material property of various polymeric materials. However, only a few experimental and theoretical investigations on crack, void and craze healing phenomena for various polymeric materials have been reported up to date [1, 2, 3]. This may be partly due to the complications of healing processes and lacking of appropriate theoretical developments. Recently, some investigators have been urged to study the healing phenomena of various polymenic materials since the significance of the use of polymer based alloys or composites has been raised in terms of specific strength and energy saving. In the earlier published reports [1, 2, 3, 4], the crack and void healing velocity, healing toughness and some other healing mechanical and physical properties were measured experimentally and compared with predicted values by utilizing a simple model such as the reptation model under some resonable assumptions. It seems, however, that the general acceptance of the proposed modeling analyses is yet open question. The crack healing processes seem to be complicate and highly dependent on the state of virgin material in terms of mechanical and physical properties. Furthermore, it is also strongly dependent on the histories of crack, craze and void development including fracture suface morphology, the shape of void and the degree of disentanglement of fibril in the craze. The rate of crack healing may be a function of environmental factors such as healing temperature, time and pressure which gives different contact configurations between two separated surfaces. It seems to be reasonable to assume that the crack healing processes may be divided in several distinguished steps like stress relaxation with molecular chain arrangement, surface contact (wetting), inter- diffusion process and com;oete healing (to obtain the original strength). In this context, it is likely that we no longer have to accept the limitation of cumulative damage theories and fatigue life if it is probable to remove the defects such as crack, craze and void and to restore the original strength of polymers or polymer based compowites by suitable choice of healing histories and methods. In this paper, we wish to present a very simple and intuitive theoretical model for the prediction of healed fracture toughness of cracked or defective polymeric components. The central idea of this investigation, thus, may be the modeling of behavior of chain molecules under healing conditions including the effects of chain scission on the healing processes. The validity of this proposed model will be studied by making comparisons between theoretically predicted values and experimentally determined results in near future and will be reported elsewhere.

• 한국수산과학회지
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• 제52권6호
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• pp.571-579
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• 2019

Surimi has been widely investigated for developing fish snacks; however, few studies have examined the optimal drying conditions of surimi for fish snacks. This study used a response surface methodology to optimize the drying conditions for the overall acceptance of fish snacks. The drying temperature (X₁, 51-65℃) and drying time (X₂, 1.5-2.5 h) were chosen as independent variables. The dependent variables were overall acceptance (Y₁, points), hardness (Y₂, N), moisture content of the dried intermediate product (Y₃, %), and volatile basic nitrogen of the fried final product (Y₄, mg/100 g). The estimated optimal conditions for overall acceptance (Y₁) were X₁=64℃ and X₂=2 h. The predicted values of the dependent variables at the optimal conditions were overall acceptance (Y₁)=8.60 points, hardness (Y₂)=10.07 N, and moisture content of the dried intermediate product (Y₃)=10.00% and were similar to the experimental values. Scanning electron microscopy images revealed that the drying conditions affected the microstructure of the fish snacks. Our results could be used to increase the productivity of fish snacks made by small- and mid-sized seafood companies.

• 한국세라믹학회지
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• 제39권11호
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• pp.1103-1107
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• 2002

생체재료의 일환으로 사용되고 있는 ${\beta}$-TCP(${\beta}$-Tricalcium Phosphate)를 합성하기 위하여 주원료인 칼슘을 화학약품이 아닌 천연재료인 달걀껍질을 이용하여 실험을 하였고, 이를 인산(phosphoric acid)과 혼합하여 ${\beta}$-TCP를 합성하였다. 본 연구에서는 인산의 혼합 량, 하소온도의 변화 그리고 달걀껍질의 출발물질 상태 등의 변수를 두고 실험을 실시하였다. 실험 변수에 따른 결과는 XRD 분석에 의해 결정상을 관찰하고, SEM에 의해 미세구조를 관찰하여 특성분석을 하였다. $900{\circ}$에서 하소한 달걀껍질을 인산과 함께 습식으로 볼 밀링 한 후, 이를 건조시켜 $900{\circ}$에서 1시간 동안 열처리하여 비교적 좁은 입도분포의 ${\beta}$-TCP 분말을 얻을 수 있었다. 차후 합성된 분말의 소결체를 이용하여, 생체 친화성과 뼈 속으로 대체되는 속도 등을 실험할 예정이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.118-119
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• 2013

High power, short wavelength red laser diodes (LDs) have attracted significant interests in a variety of fields due to their advantages in terms of reliability, compactness and cost. The higher brightness for human eyes is required, the shorter wavelength like 630 nm is necessary with higher output power. In this respect, LDs are promising as alternative candidates of gas or dye lasers for such applications due to their small size, high optical/electrical power conversion efficiency, robustness and so on. The crystalline quality of GaInP-AlGaInP multiple quantum wells (MQWs) and AlInP cladding layers is a crucial part in the device performance of GaInP red LDs. Here, we first investigated the effect of Si diffusion on the optical properties of GaInP-AlGaInP MQWs grown with different growth temperatures. Secondary ion mass spectroscopy (SIMS) measurements revealed that both the Mg and Si diffusion into MQW active region was significant. To reduce such diffusion, we employed undoped Mg and Si diffusion barrier and could improve the properties.Without both Mg and Si diffusion barriers, no lasing emission was observed. However, lasing emission was observed clearly for the red LDs with both Mg and Si diffusion barriers. We then investigated the temperature dependent optical properties of MQW layers grown with different well thicknesses (6, 8 and 10 nm). When the well thickness was 10 nm, the better crystalline quality was obtained. However, the observed LD performances were similar, probably due to the defects and impurities in the AlGaInP layer. Further investigation with the detailed analyses will be presented later.

• Fisheries and Aquatic Sciences
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• 제15권4호
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• pp.299-303
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• 2012

Barbel structure and regenerated barbel length in the juvenile Chinese longsnout catfish Leiocassis longirostris (G$\ddot{u}$nther), were evaluated. The barbles consisted of an epidermis, a dermis, and a central rod. The epidermis harbored taste buds, granular cells and epidermal cells. The taste buds were basophilic and situated along the distal portion of the epidermis. The dermis was composed of loose connective tissue containing blood vessels pigment cells. The innermost central region was cartilage enclosed within layers of muscle layers. After 30 days, the regenerated barbel length measured $0.92{\pm}0.404mm$ at $15^{\circ}C$ (regenerated growth curve: y = 0.5085x + 4.0678, $r^2$ = 0.9654, where y is regenerated length and x is experimental period in days), $1.88{\pm}0.521mm$ at $20^{\circ}C$ (y = 0.1806x + 4.808, $r^2$ = 0.9822), and $6.44{\pm}0.751mm$ at $25^{\circ}C$ (y = 0.0914x + 4.9918, $r^2$ = 0.9944). Fifteen days after amputation, the regenerated length was significantly longer at $25^{\circ}C$ than at 15 or $20^{\circ}C$ (P < 0.05). The barbels of the Chinese longsnout catfish was the tender and flexible type, and our experimental findings provide evidence of temperature-dependent regeneration. Additional investigation of the behavior and physiology of the Chinese longsnout catfish is needed, particularly histological studies of regenerated barbels and the measurements of the numbers of taste buds per barbel under various environmental conditions.