항공사 기단의 상태변화 시각화에 관한 연구

이용화,이주환,이금진,Lee, Yonghwa,Lee, Juhwan,Lee, Keumjin 한국항공운항학회 2021 한국항공운항학회지 Vol.29 No.2

Airline schedule is the most basic data for flight operations and has significant importance to an airline's management. It is crucial to know the airline's current schedule status in order to effectively manage the company and to be prepared for abnormal situations. In this study, machine learning techniques were applied to actual schedule data to examine the possibility of whether the airline's fleet state could be artificially learned without prior information. Given that the schedule is in categorical form, One Hot Encoding was applied and t-SNE was used to reduce the dimension of the data and visualize them to gain insights into the airline's overall fleet status. Interesting results were discovered from the experiments where the initial findings are expected to contribute to the fields of airline schedule health monitoring, anomaly detection, and disruption management.

역상 액체 크로마토그래피에 의한 비이온 계면활성제의 Propylene oxide 분포 및 Fatty alcohol 의 분석

이용화,박홍순,최규열,이재덕,안호정 ( Yong Hwa Lee,Hong Soon Bak,Kyu Yeol Choi,Jae Duk Lee,Ho Jeong Ahn ) 한국공업화학회 1997 공업화학 Vol.8 No.2

본 연구는 역상 액체 크로마토그래피를 이용하여 비이온 계면활성제의 propylene oxide 분포 및 고급 지방 알콜의 최적 분석 조건을 조사하였다. Propylene oxide 분포 및 지방 알콜의 탄소 길이를 분석하기 위해 UV 검출기를 사용할 수 있도록 유도체화 시켰으며 최적 분리 조건을 얻기 위해 분리관의 영향과 이동상의 조성 등을 실험하였다. 분리관은 Waters SymmetryC_8(3.9×150mm)을 사용하였고 이동상은 methanol과 물을 이용한 기울기 용리에 의한 분석이 최적 조건이었다. 그리고 이들의 용리 거동은 log k` 와 물의 부피 분율을 도시한 결과 좋은 직선성을 얻었고 고급 알콜의 정량성을 알아보기 위하여 검량선을 도시한 결과 직선성이 좋은 결과를 얻었다. In this study, the optimum analytical conditions for determination of distribution of propylene oxide in a nonionic surfactant and separation of fatty alcohols were investigated by Reversed Phase High Performance Liquid Chromatography. To analyse the distribution of propylene oxide (PO) and carbon chain length of a fatty alcohol, we derivatized samples for the purpose of using a UV detector. Also, we studied the influences of columns and mobile phase composition to obtain the optimum separation conditions. In our experiment, Waters Symmetry C_8(3.9 X 150mm) column was used. And the optimum condition were obtained by gradient elution with methanol and water as the mobile phase. In the plot of log k` vs composition of water in the binary phase, the linerality was very good. We ploted the calibration curve to conform the quality of fatty alcohol, a good linerality was obtained.

Mutation analysis of PAH gene and characterization of a recurrent deletion mutation in Korean patients with phenylketonuria

이용화,이동환,Nam-Doo Kim,Seung-Tae Lee,Jee Young Ahn,최태윤,이유경,Sun-Hee Kim,김종원,기창석 생화학분자생물학회 2008 Experimental and molecular medicine Vol.40 No.5

Phenylketonuria (PKU; MIM 261600) is an autosomal recessive metabolic disorder caused by a deficiency of phenylalanine hydroxylase (PAH; EC 1.14.16.1). Point mutations in the PAH gene are known to cause PKU in various ethnic groups, and large deletions or duplications account for up to 3% of the PAH mutations in some ethnic groups. However, a previous study could not identify ~14% of the mutant alleles by sesequence analysis in Korean patients with PKU, which suggests that large deletions or duplication might be frequent causes of PKU in Koreans. To test this hypothesis, we performed multiplex ligation-dependent probe amplification (MLPA) for the identification of uncharacterized mutant alleles after PAH sequence analysis of 33 unrelated Korean patients with PKU. Bi-directional sequencing of the PAH exons and flanking intronic regions revealed 27 different mutations, including four novel mutations (two missense and two deletion mutations), comprising 57/66 (86%) mutant alleles. MLPA identified a large deletion that encompassed exons 5 and 6 in four patients, another large deletion that extended from exon 4 to exon 7 in one patient, and a duplication of exon 4 in one patient. Chromosomal walking characterized the deletion breakpoint of the most common large deletion that involved exons 5 and 6 (c.456_706+138del). The present study shows that the allelic frequency of exon deletion or duplication is 9% (6/66) in Korean PKU patients, which suggests that these mutations may be frequent causes of PKU in Korean subjects.

평판전열면(平板傳熱面)에 충돌(衝突)하는 2차원충돌분류계(二次元衝突噴流系)의 열전달특성(熱傳達特性)에 관(關)한 연구(硏究)

이용화,김상필,서정윤,Lee, Y.H.,Kim, S.P.,Seo, J.Y. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.1

The purpose of this study is to investigate the heat transfer characteristics and the flow structure in the case of rectangular air jet impinging vertically on the flat heating surface. The maximum value of Nusselt number at stagnation point is observed at H/B=10. It is found that this trend has been caused by the effect of stretching of large scale vortex in the stagnation region. For potential core region the Nusselt number distribution in the downstream of the stagnation point decreases gradually and begins to increase at about X/B=3. From the flow visualization it could be seen that small eddy produced from the nozzle edge grows in large scale and that large scale eddy disturbed the thermal boundary layer on the heating plate. The local average Nusselt number becomes maximum at X/B=0.5 regardless of H/B variation.

경북 구룡포 해역에서의 냉수 발생과 어장 피해

이용화,심정희,최양호,김상우,심정민,Lee, Yong-Hwa,Shim, JeongHee,Choi, Yang-ho,Kim, Sang-Woo,Shim, Jeong-Min 해양환경안전학회 2016 해양환경안전학회지 Vol.22 No.6

경상북도 구룡포 해역에서 하계 냉수 발생 특성과 어류 폐사를 유발하는 냉수대 강도를 파악하고자 2007년 8~11월 멍게양식장에 수온로거를 설치하여 수층별 수온을 측정하였으며, 2015년과 2016년은 국립수산과학원 실시간어장정보시스템의 표층수온 자료를 이용하였다. 동해 남부해역의 냉수대 발생 원리와 부합하게 남~남서풍이 강하게 불 때 용승으로 표층수온이 급격히 하강하였으며(2007년 8월 하순, 9월 20~22일, 2015년 7월 13~15일), 반대로 북~북동풍이 우세할 때 저층수온이 급상승하는(2007년 9월 5~7일, 9월 16~18일) 것으로 나타났다. 그 외에도 7~8월 구룡포 해역에 나타나는 약한 강도의 표층수온의 하강과 상승은 바람 방향과 밀접한 관계가 있는 것으로 나타났다. 구룡포 해역에서 최대풍속이 5 m/s 이상인 남~남서풍이 최소 이틀 이상 유지되면 표층수온이 약 $10^{\circ}C$ 이하로 하강하는 강한 냉수대가 발생하고 이로 인해 어류 폐사가 발생하는 것으로 파악되었다. 이를 바탕으로 포항기상대의 최대풍속과 최대풍속 풍향을 이용하여 냉수발생지수(Cold Water Index)를 정의하고 계산한 결과, $CWI_{2d}$(CWI 2일 평균)가 100 이상일 때 어류 폐사가 주로 발생하였으며, $CWI_{4d}$(CWI 4일 평균)는 7~8월 구룡포 표층수온과 높은 음의 상관성을 나타내었다($R^2=0.5$). 2007년 10월 30 m 수층의 수온 일변화($7{\sim}23^{\circ}C$)는 조석변화와 일치하는 주기와 스펙트럼을 보였으며, 이는 북한한류수 영향인 것으로 파악된다. 이와 같이 조석과 북한한류수로 인한 일변화가 어류 가 두리가 설치된 수심에도 영향을 미친다면 어업 피해로 이어질 수 있으므로 정밀한 조사가 필요할 것으로 생각된다. To understand the characteristics and strength of the cold water that has caused damage to marine-culturing farms around Guryongpo, in the southwestern part of Korea, surface and water column temperatures were collected from temperature loggers deployed at a sea squirt farm during August-November 2007 and from a Real-time Information System for Aquaculture environment operated by NIFS (National Institute of Fisheries Science) during July-August 2015 and 2016. During the study period, surface temperature at Guryongpo decreased sharply when south/southwestern winds prevailed (the 18-26th of August and 20-22nd of September 2007 and the 13-15th of July 2015) as a result of upwelling. However, the deep-water (20-30m) temperature increased during periods of strong north/northeasterly winds (the 5-7th and 16-18th of September 2007) as a result of downwelling. Among the cold water events that occurred at Guryongpo, the mass death of cultured fish followed strong cold water events (surface temperatures below $10^{\circ}C$) that were caused by more than two days of successive south/southeastern winds with maximum speeds higher than 5 m/s. A Cold Water Index (CWI) was defined and calculated using maximum wind speed and direction as measured daily at Pohang Meteorological Observatory. When the average CWI over two days ($CWI_{2d}$) was higher than 100, mass fish mortality occurred. The four-day average CWI ($CWI_{4d}$) showed a high negative correlation with surface temperature from July-August in the Guryongpo area ($R^2=0.5$), suggesting that CWI is a good index for predicting strong cold water events and massive mortality. In October 2007, the sea temperature at a depth of 30 m showed a high fluctuation that ranged from $7-23^{\circ}C$, with frequency and spectrum coinciding with tidal levels at Ulsan, affected by the North Korean Cold Current. If temperature variations at the depth of fish cages also regularly fluctuate within this range, damage may be caused to the Guryongpo fish industry. More studies are needed to focus on this phenomenon.

2차원(次元) 충돌분류(衝突噴流)의 열전달(熱傳達) 증진(增進)에 관(關)한 실험적(實驗的) 연구(硏究) (사각(四角) Rib폭(幅)의 효과(效果))

이용화,이관석,서정윤,Lee, Y.H.,Rhee, K.S.,Seo, J.Y. 대한설비공학회 1988 설비저널 Vol.17 No.4

The impinging air jet system is still being used in the various fields with its inherent merits, that is, the easiness in engineering application and high heat transfer coefficients at stagnation point. The purpose of this study is augmentation of heat transfer without additional power in the rectangular air jet which impinges vertically to the heating surface. As a method of passive heat transfer augmentation in a two-Dimensional impinging jet, the transverse-repeated surface roughness of square cross-section is used. This paper deals with the experimental study on the characteristics of heat transfer at the x-direction in between nozzle exit and heating surface of flat plate, and that of ribbed plate. And this study also investigates the effect of square rib widths. The integral average heat transfer coefficient of ribbed plate is about 2.2 times larger than that of flat plate.

충돌판(衝突板) 근방(近傍)에 배열(配列)된 2차원(次元) rod가 충돌분류(衝突噴流) 열전달(熱傳達)에 미치는 영향(影響) (1) : 전열면(傳熱面)-rod간(間)의 간극효과(間隙效果)

이용화,서정윤,Lee, Yong Hwa,Seo, Jeong Yun 대한설비공학회 1989 설비공학 논문집 Vol.1 No.1

The purpose of this study is augmentation of heat transfer without additional power in a rectangular impinging air jet. As a method of passive heat transfer augmentation in a two-dimensional air jet, heat transfer surface of flat plate with rods is used. This study, particularly in the wall jet rigeon, investigates the effect of the clearance between the flat plate and rod. Mechanism of heat transfer enhancement is investigated by measuring the local heat transfer coefficient. It is concluded that the superposition of the effects of flow accelerlation through the clearance between the flat plate and the rod, and reattachment of the flow was the cause of the excellent performance. The overall heat transfer rate of flat plate with rods is about 1.5 times larger than that of flat plate without rods.

하수처리수이용 흡수식냉동사이클의 해석

이용화,Lee, Y.H. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.2

The gas-fired absorption refrigeration system to utilize treated sewage is available for environmental protection and energy conservation. Simulation analysis on the double-effect absorption refrigeration cycles with parallel or series flow type has been performed. The working fluid is Lithium Bromide and water solution. The main purpose of this study is evaluating the possibilities of effective utilization of treated sewage as a cooling water for the absorber and condenser. The efficiency of a couple of cycles has been studied and simulation results show that higher coefficient of performance could be obtained for parallel flow type. The other purpose of the present study is to determine the optimum designs and operating conditions based on the operating constraints and the coefficent of performance in the paralledl flow type.

2006년 하계 경북 연안의 수온변화와 우렁쉥이 폐사

이용화,심정민,김영숙,황재동,윤석현,이주,진현국,Lee, Yong-Hwa,Shim, Jeong-Min,Kim, Young-Suk,Hwang, Jae-Dong,Yoon, Suk-Hyun,Lee, Chu,Jin, Hyun-Gook 해양환경안전학회 2007 해양환경안전학회지 Vol.13 No.4

2006년 8월 경북 연안의 우렁쉥이 앙식장에서 대량폐사가 발생하였다. 폐사 원인을 규명하기 위하여 폐사 직후 폐사가 발생한 양식장을 대상으로 수질환경 조사와 병리학적 조사를 실시하였으나 특이점을 발견하지 못하였다. 그래서 폐사가 발생하기 직전 동해에 영향을 미친 10호 태풍 '우쿵'이 우렁쉥이 폐사에 영항을 미쳤을 것으로 가정하고 태풍 '우쿵' 통과 전후의 해황 자료를 분석하였다. 태풍 우쿵의 영향을 받기 전인 8월 초 중순 동해 연안은 전반적으로 저층 냉수의 용승으로 인하여 수심 10m 이심에서는 $15^{\circ}C$ 이하의 찬물이 존재하고 있었다. 그 후 매풍 '우쿵'의 영향으로 인한 북풍이 약 5일간 지속되면서 수온이 높은 외측의 표층수가 연안으로 밀려와 침강하는 현상(에크만 효과)이 발생하여 우렁쉥이가 매달려 있는 수심 $10{\sim}20m$의 수은이 일시에 $10^{\circ}C$ 이상 상승하여 약 5일간 지속되었다. 2006년 경북 연안의 양식 우렁쉥이는 장기간 냉수에 적응되어 있다가 태풍 '우쿵'의 영향으로 수온이 급상승함에 따른 수온 스트레스로 인하여 대량폐사된 것으로 추정된다. Mass mortalities of the farmed sea squirt, Halocynthia roretzi, occurred in August, 2006 along the Gyeongbuk coasts of the East Sea without any pathological symptom. Suspecting the No. 10 typhoon, Wukong, which had passed over the relevant locations in the middle of August, 2006 as a culprit of the mortalities, we compared water temperature stratifications of the affected coasts before and after the typhoon. Just prior to the typhoon, cold waters lower than $15^{\circ}C$ were stratified at depths deeper than 10m probably by a persisting upwelling of cold bottom waters. The typhoon enforced water off-coast waters into coasts for 5 days, replacing the cold waters at depths $10{\sim}20m$ which can be justified by Ekman Spiral Effect. The results were an increment of water temperature by $10^{\circ}C$ and more at depths where sea squirts were suspended. The sudden elevation of water temperature might drive the sea squirts under abnormal stress to mass mortality.

배수관내의 압력 및 유동특성

이용화,박정원,Lee, Y.H.,Park, J.W. 대한설비공학회 1997 설비저널 Vol.26 No.5