Onset of convection in a porous mush during binary solidification

황인국,최창균 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.2

The onset of convection in a mushy layer during solidification of a binary melt is investigated by using the propagation theory we have developed. The critical conditions for the mushy-layer-mode of instability are obtained numerically for aqueous ammonium chloride solution. The mush thickness at the onset of convection is predicted as a function of the solution viscosity and compared with the experimental data. The onset time of the mushy-layer-mode convection has a minimum point with varying the superheat. When the superheat is large, the mushy layer grows slowly and a long time is required for the onset of convection

Reverse Offset Printed Silver Nanowire Electrodes with Large-Area and Fine Micro-Patterning

황인국,김종윤,박규태,이윤구 한국고분자학회 2020 한국고분자학회 학술대회 연구논문 초록집 Vol.45 No.2

Mush 층과 액체층에서 대류의 발생

黃仁菊 水原大學校 2003 論文集 Vol.21 No.-

The convective instabilities of a binary melt during directional solidification are analyzed under linear stability theory by using the propagation theory. The stability equations for liquid and mushy layers are transformed similarly by using the developing mushy-layer thickness as the length scaling factor. The onset conditions to mark convective motion in the liquid and mushy layers are obtained numerically for time-dependent solidification. The results show that for small Lewis numbers the mushy-layer-mode convection occurs faster than the boundary-layer-mode convection and the system is more stable with decreasing the superheat.

가열 시간과 고명에 따른 토란병의 품질특성

황인국,박보람,유선미,Hwang, In Guk,Park, Bo Ram,Yoo, Seon Mi 한국식품영양학회 2013 韓國食品營養學會誌 Vol.26 No.4

본 연구에서는 수문사설 에 수록된 토란병의 제조방법을 확립하기 위하여 토란의 가열 시간 및 고명에 따라 토란병을 제조하고, 품질특성을 비교 분석하였다. 가열 시간에 따른 수분, 조단백질, 조지방 및 조회분 함량은 각각 83.42~84.61%, 1.25~1.31%, 0.08~0.11%, 0.62~0.81% 범위로 조지방은 유의적인 차이가 없었으며, 조회분은 가열처리로 인해 유의적으로 감소하였다. 토란의 주요 유리당은 fructose, glucose 및 sucrose가 검출되었고, 가열 시간에 따라 각각 0.17~0.33%, 0.16~0.29% 및 0.26~0.38% 범위로 15분 가열처리 때까지 유의적으로 감소하였다. 경도 역시 가열 시간이 늘어날수록 2.75 kg에서 0.14 kg까지 감소하였다. 가열 시간에 따른 관능특성을 평가한 결과, 향과 맛은 각 처리구간 유의적인 차이를 보이지 않았고, 질감과 전반적인 기호도는 5분 처리구가 다른 처리구에 비해 유의적으로 낮게 평가되었으며, 10분 처리 이후에는 큰 차이를 보이지 않았다. 이상의 결과, 토란병의 제조 시 가열 시간은 10분이 바람직할 것으로 판단된다. 잣고물, 콩고물, 검은 깨고물 및 밤고물 등 고명 종류에 따른 토란병의 관능특성을 평가한 결과, 색, 향, 질감, 맛 및 전반적인 기호도는 각각 5.20~7.50, 5.40~7.70, 6.10~7.00, 6.10~7.20 및 6.20~7.60 범위로 평가되었고, 콩고물을 묻힌 토란병이 모든 항목에서 가장 높게 평가되었다. This study was performed to determine the best conditions for preparing Toranbyung. We examined different boiling periods (0~20 min) and types of Gomyeong (pine nut, soy, black sesame, and chestnut powder), as recorded in "Sumunsasul". The boiled taros were evaluated for proximate composition, free sugar contents, and Hunter's color values. In addition, the sensory characteristics of Toranbyung boiled for different periods and prepared using different types of Gomyeong were investigated. The moisture, protein, fat, and ash contents of taro decreased by 83.42~84.61%, 1.25~1.31%, 0.08~0.11%, and 0.62~0.81%, respectively, as the length of boiling time increased. Fructose, glucose, and sucrose, the major free sugars found in taro, decreased by 0.17~0.33%, 0.16~0.29%, and 0.26~0.38%, respectively, as the length of boiling time increased. Sensory evaluation indicated no significant difference in the flavor and taste of Toranbyung boiled for different periods of time. However, Toranbyung boiled for 10 min was significantly better and was found to be the most acceptable among all the samples. Furthermore, sensory evaluation of Toranbyung prepared with different types of Gomyeong indicated that the Toranbyung prepared with soy powder was favored over Toranbyung prepared using other types of Gomyeong. In conclusion, we determine that the best conditions for preparing Toranbyung were boiling for 10 min and using soy powder as the Gomyeong.

산과 열처리에 따른 마늘 Fructan과 항산화활성 변화

황인국,김기찬,최성길,이준수,정헌상 경상대학교 농업생명과학연구원 2010 농업생명과학연구 Vol.44 No.1

마늘의 주요 저장성분인 fructan을 산 가수분해시키고 열처리에 따른 폴리페놀함량과 항산화활성의 변화를 살펴보았다. 마늘 fructan의 최적 산가수분해 조건은 0.3N H2SO4으로 5분간 반응시켰을 때로 나타났다. 열처리에 의한 fructan 함량은 열처리 온도가 증가함에 따라 240.5 mg/g에서 2.0 mg/g으로 분해되어 감소하였으며, 총 폴리페놀 함량은 열처리 온도 증가에 따라 0.85 mg/g에서 13.74 mg/g으로 증가하였고, 항산화활성(IC50)은 열처리온도가 증가에 따라 52.9 mg/mL에서 1.5 mg/mL으로 증가하였다. 열처리 후 산가수분해시 총 폴리페놀 함량 및 항산화활성은 증가하였다. 마늘 fructan을 분해하여 식품소재로서의 활용과 동시에 항산화활성을 강화시키기 위한 열처리 조건으로는 130℃, 2시간 처리가 적합한 것으로 판단되었다. This study was to investigate the fructose, total fructan, polyphenol contents, and antioxidant activity of garlic treated acid and heat(100~140°C for 2 hr). Optimum condition of acid hydrolysis of fructan was 0.3N H2SO4 and 5 min. As increasing heating temperature, fructose content was significantly increased from 17.1 to 189.9 mg/g whereas total fructan content was decreased from 248.1 to 2.0 mg/g. The fructan was mostly hydrolyzed by heating at 130°C for 2 hr. The polyphenol contents was increased from 0.85 to 13.74 mg/g increasing heating temperature and also antioxidant activity was significantly increased. The polyphenol contents and antioxidant activity on acid hydrolysate after heating was slightly increased

[P10-57] 열처리조건에 따른 인삼의 특성 변화

황인국,유정식,김자영,우관식,이준수,정헌상,양승준 한국식품영양과학회 2005 한국식품영양과학회 학술대회발표집 Vol.2005 No.10

위로부터 응고되는 순 용융액의 열적 불안정성

황인국,최창균 ( I . G . Hwang,C . K . Choi ) 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.1

제한된 범위의 Signed-Digit Number 인코딩을 이용한 병렬 십진 곱셈기 설계

황인국,김강희,윤완오,최상방,Hwang, In-Guk,Kim, Kanghee,Yoon, WanOh,Choi, SangBang 대한전자공학회 2013 전자공학회논문지 Vol.49 No.11

본 논문에서는 제한된 범위의 Signed-Digit number 인코딩과 축약 단계를 이용한 고정소수점 병렬 십진 곱셈기를 제안한다. 제안한 병렬 십진 곱셈기는 승수와 피승수를 제한된 범위의 SD number로 인코딩하여 캐리 전달 지연 없이 빠르게 부분곱을 생성한다. 인코딩에 사용하는 숫자의 범위를 줄임으로써 SD number 다중 피연산자 덧셈의 한번에 연산 가능한 피연산자의 개수가 늘어나게 되고, 이에 따라 부분곱 축약 단계의 연산을 빠르게 수행 할 수 있다. 제안한 병렬 십진 곱셈기의 성능 평가를 위해 Design Compiler에서 SMIC사의 180nm CMOS 공정 라이브러리를 이용하여 합성한 결과 기존의 Signed-Digit number를 이용한 병렬 십진 곱셈기보다 전체 지연시간은 4.3%, 전체 면적은 5.3% 감소함을 확인 하였다. 전체 지연시간 및 면적에서 부분곱 축약 단계가 차지하는 비중이 가장 크므로 부분곱 생성 단계에서 약간의 지연시간 및 면적 증가가 있음에도 불구하고 전체 지연시간과 면적이 감소하는 결과를 얻을 수 있다. In this paper, parallel decimal fixed-point multiplier which uses the limited range of Singed-Digit number encoding and the reduction step is proposed. The partial products are generated without carry propagation delay by encoding a multiplicand and a multiplier to the limited range of SD number. With the limited range of SD number, the proposed multiplier can improve the partial product reduction step by increasing the number of possible operands for multi-operand SD addition. In order to estimate the proposed parallel decimal multiplier, synthesis is implemented using Design Compiler with SMIC 180nm CMOS technology library. Synthesis results show that the delay of proposed parallel decimal multiplier is reduced by 4.3% and the area by 5.3%, compared to the existing SD parallel decimal multiplier. Despite of the slightly increased delay and area of partial product generation step, the total delay and area are reduced since the partial product reduction step takes the most proportion.

이성분 응고중에 mush 층과 액체층의 온도 및 농도분포

황인국 수원대학교 산업기술연구소 1998 산업기술연구소논문집 Vol.13 No.-

When a binary melt is solidified from a cooling boundary, thermal or compositional boundary layers develop in liquid and mushy layers. The governing equations, which link the liquid layer with the mushy layer, are derived by using the similarity variable. The temperature and concentration profiles in the liquid and mushy layers are investigated numerically. The results show that the compositional boundary-layer thickness increases with increasing the Lewis number.

소음성난청에서 구형낭 기능의 평가

황인국,문지현,김영효,김규성,정윤건,최호석 대한평형의학회 2008 Research in Vestibular Science Vol.7 No.1

Background and Objectives: Considering saccular receptors are coupled physically with the auditory receptors, VEMP test may provide the information that in the noise induced hearing loss with or without dizziness, damage to the vestibular system, especially saccule is a potential organ with cochlear damage. Material and Methods: 11 patients (22 ears) with HF-SNHL greater than 55dB and 10 patients (10 ears) with sudden hearing loss of varying degree HL as positive control but without clinical manifestations of vestibular pathology tested for vestibular function test was enrolled. VEMP test was done. The results were compared with those of 9-healthy referents (18 ears) examined in the same way. Results: VEMP wave was significantly abolished as twelve of 22 (54.5%) with HF-SNHL, five of 13 (38.5%) and Control group (100%). Though there was no statistically significant relation with P13, N23 latency delay in each group, NIHL showed P13, N23 latency delay trend compared with controls. Conclusions: Patients with noise induced hearing loss showed significantly more saccular deterioration, estimated as negative VEMP responses than did the controls. This suggests subclinical disturbances of the vestibular system especially of the saccule in noise induced hearing loss. Background and Objectives: Considering saccular receptors are coupled physically with the auditory receptors, VEMP test may provide the information that in the noise induced hearing loss with or without dizziness, damage to the vestibular system, especially saccule is a potential organ with cochlear damage. Material and Methods: 11 patients (22 ears) with HF-SNHL greater than 55dB and 10 patients (10 ears) with sudden hearing loss of varying degree HL as positive control but without clinical manifestations of vestibular pathology tested for vestibular function test was enrolled. VEMP test was done. The results were compared with those of 9-healthy referents (18 ears) examined in the same way. Results: VEMP wave was significantly abolished as twelve of 22 (54.5%) with HF-SNHL, five of 13 (38.5%) and Control group (100%). Though there was no statistically significant relation with P13, N23 latency delay in each group, NIHL showed P13, N23 latency delay trend compared with controls. Conclusions: Patients with noise induced hearing loss showed significantly more saccular deterioration, estimated as negative VEMP responses than did the controls. This suggests subclinical disturbances of the vestibular system especially of the saccule in noise induced hearing loss.