시화호 배수갑문 개폐에 따른 탁도와 부유물질의 분포와 특성

최정훈,홍대벽,임종완,Choi Jung-Hoon,Hong Dae-Byuk,Lim Jong-Wan 한국관개배수위원회 2002 한국관개배수논문집 Vol.9 No.1

The Lake Sihwa gradually changes from freshwater lake to saline lake due to inflow of seawater by sluice gates . The changes of lake water are closely related to characteristic and distribution of turbidity and suspended matter. During the period April-Ma

폐 산세 용액으로부터 공침 반응에 의한 지르코늄 회수 시 BaF₂ 입도 영향 및 Ba₂ZrF₈의 진공증류 특성

최정훈,하이크 네르시시안,한슬기,김영민,박철호,강종원,나기현,김정훈,이종현,Choi, Jeong Hun,Nersisyan, Hayk,Han, Seul Ki,Kim, Young Min,Park, Cheol-Ho,Kahng, Jong Won,Na, Ki Hyun,Kim, Jeong hun,Lee, Jong Hyeon 한국자원리싸이클링학회 2017 資源 리싸이클링 Vol.26 No.6

핵연료 피복관은 필거링 및 열처리 공정에 의해 제조되며, 핵연료 피복관 표면의 불순물 및 산화층을 제거하기 위해 산세 공정이 진행된다. 산세 공정 중 산세 용액으로 지르코늄이 용해되어 포화상태가 될 시 폐 산세 용액은 전량 폐기 되며 용액 내 지르코늄 또한 폐기된다. 그러므로 지르코늄을 재활용하기 위해 $BaF_2$를 폐 산세 용액에 첨가하여 공침 반응에 의해 $Ba_2ZrF_8$을 형성시켰다. 한편, 전해제련을 통해 Zr을 회수하기 위해서는 $Ba_2ZrF_8$을 전해질로 사용해야하지만, 용융점이 $1053^{\circ}C$로 높다. 따라서 $ZrF_4$를 첨가하여 용융점을 낮추어야한다. 본 연구에서는 $Ba_2ZrF_8$을 진공 증류를 통해 $BaF_2$ 및 $ZrF_4$로 분리하는 연구를 진행하였다. 먼저, $BaF_2$ 입자크기($1{\mu}m$, $35{\mu}m$, $110{\mu}m$)에 따른 침전 특성을 실험하였다. 그리고 진공 증류를 통해 수득된 $BaF_2$를 볼밀링을 통해 분쇄하였으며, 침전 공정을 거치지 않은 $BaF_2$와 침전 효율을 비교하였다. Nuclear fuel cladding tube is fabricated by pilgering and annealing process. In order to remove impurity and oxygen layer on the surface, pickling process is carried out. When Zirconium(Zr) is dissolved and saturated in acid solution during the pickling process, all the waste acid including Zr is disposed. Therefore, $BaF_2$ is added into the waste acid to extract Zr and $Ba_2ZrF_8$ is subsequently formed. To recycle Zr by electrowinning process, $Ba_2ZrF_8$ is used as electrolyte, but it has high melting point ($1053^{\circ}C$). $ZrF_4$ should be added into $Ba_2ZrF_8$ to decrease the melting point. In this paper, it was investigated that $Ba_2ZrF_8$ was separated to $BaF_2$ and $ZrF_4$ by vacuum distillation. Firstly, $BaF_2$ with different particle size ($1{\mu}m$, $35{\mu}m$, $110{\mu}m$) was added into the waste acid and the respective precipitation property was estimated. $BaF_2$ obtained by vacuum distillation was shattered by ball-milling with different time. The precipitation efficiency was compared with $1{\mu}m$ of ${BaF_2}^{\prime}s$ one, which was not used as precipitation agent.

시화방조제 건설에 따른 퇴적상 변화

최정훈,Choi Jung-hoon 한국관개배수위원회 2001 한국관개배수논문집 Vol.8 No.2

Sihwa dyke was constructed during the period from June, 1987 to January, 1994 and the sluice gates were opened to allow sea water intrusion and outflow to improve water quality of the lake since June, 1997. Bottom sediment samples from 29 stations were co

Fatal Facial Mucormycosis on a Diabetic Patient: A Case Report

최정훈,김영준,권지은,김훈,남상현,최영웅,Choi, Jung-Hun,Kim, Young-Joon,Kwon, Ji-Eun,Kim, Hoon,Nam, Sang-Hyun,Choi, Young-Woong Korean Society of Plastic and Reconstructive Surge 2011 Archives of Plastic Surgery Vol.38 No.1

Purpose: Mucormycosis generally occurs in patients with uncontrolled diabetes mellitus and immunocompromised conditions. It is rare, but once a patient is infected with it, it can occur as a rapidly extending, aggressive, and life-threatening rhinocerebral infection with a high mortality rate. Methods: A 70-year-old female patient had a 40 years of history of adult onset diabetes mellitus. She presented herself with severe right hemifacial pain, swelling, and weakness for 3 days and was admitted to ENT. On a facial computed tomography (CT) scan, it was found that her infection extended from her inferior temporal scalp to her submental area and involved her submandibular, masseter, prevertebral, parapharyngeal, retropharyngeal, and pharyngeal mucosal space and pansinusitis. Through endoscopic sinus surgery, mucormycosis was confirmed via histologic examination. Results: Despite empiric antibiotics and amphotericin B administration, the patient was in a septic condition and in a coma. The patient's family wanted to withdraw her life support, and the patient expired. Conclusion: Mucormycosis is very rare, but is one of the disastrous complications of uncontrolled diabetes mellitus. Suspicion of its occurrence, based on identified risk factors, and its rapid diagnosis can enhance the chance of its cure.

풍력 및 태양광 발전시스템의 일반 특성과 강풍제어기 및 DC-DC컨버터에 대한 연구

최정훈,박성준,문채주,Choi, Jung-Hoon,Park, Sung-Jun,Moon, Chae-Joo 한국조명전기설비학회 2005 조명·전기설비학회논문지 Vol.19 No.1

풍력 및 태양광 발전시스템은 화석에너지의 고갈에 대한 대체에너지로 각광을 받고 있으며, 환경오염을 발생하지 않고 무한정으로 사용할 수 있으나 풍속과 태양광의 변화에 따른 안정성의 문제가 발생한다. 풍력발전시스템의 경우 태풍과 급속한 풍속의 변화에 의해 시스템의 안정성 문제가 발생한다. 본 논문에서는 풍속을 이용한 피드백 제어를 기초로 하는 자동강풍제어기를 포함하는 풍력 발전시스템을 구성하였으며, 이를 다양한 조건의 실험을 통하여 입증하였다. 태양전지 어레이의 최대 출력을 위한 MPPT제어와 고르지 못한 DC 전압을 정류하기 위하여 buck-boost컨버터를 사용하였고, 실험을 동하여 시스템 출력전류 리플 저감의 결과를 확인하였다. Wind power and photovoltaic(PV) systems are getting into the spotlight as substitute energy. But problem is happened stability by speed change of wind and the power output of the sun's ray. The power output amount according to velocity of wind power system. System breakdown can happen at change of sudden velocity, typhoon and night. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The operation of automatic tail safety controller verified by manual test. PV system is a energy change system by temperature of sun's ray and cell. Maximum power point tracking(MPPT) is used in PV systems to maximize the photovoltaic array output power. In existed PV system is low output and changeable DC voltage for boost and filtering the buck-boost converter use. But, this paper established deformed DC-DC converter. Changed Buck-boost converter's unlined output current to line output current using DC-DC converter. This is effect that reduce ripple of output current. Proved through an output waveform comparison experiment. Finally, tail safety brake controller is established to wind turbine system for stability elevation and DC-DC converter is established on PV system for stability output.

시화호 배수갑문 운용에 따른 용존산소와 pH 변화

최정훈,김미옥,Choi, Jung-Hoon,Kim, Mi-Ock 한국지구과학회 2001 한국지구과학회지 Vol.22 No.3

The variations of D.O and pH due to the inflow of seawater by sluice gates operation were observed in the Lake Shihwa, Korea. The distributions of D.O and pH were investigated at 11 stations during Feburary 1997 to July 1998. The concentration of D.O before gate operation was 10 mg/l or more all over the watershed, yet 5 mg/l or less in the water layers of 11 m or below from March to June 1997. Anoxic layer appeared in June 1997 and expanded during rainy season. The anoxic layer in the lake depleted the oxygen in seawater as seawater was inflowed. It may be interpreted that the phenomenon comes from the contact of seawater to lower fresh water. The contact of seawater in pH 7.8 to 8.2 to lower water less than pH 7.4 enhanced to oxidize. After January 1998, D.O of the lake increased over 10 mg/l and the stratification was weakened. As a result, it may be concluded that the best way to improve the water qualities is to increase the amount of seawater inflow and outflow so as not to be generated pycnocline in summer. 1997년 2월부터 1998년 7월까지 총 33회에 걸쳐 시화호내 11개 정점에서 배수갑문 개${\cdot}$폐에 따른 용존산소와 pH의 변화를 파악하였다. 해수유입이 없었던 1997년 3월부터 1997년 5월까지의 용존산소 분포는 대부분의 수층에서 10mg/l이상을 보이고 l1m 이하의 수심에서 5mg/l 이하를 나타냈다. 1997년 6월에 수심 6m 이하에서 무산소층이 나타났다. 강우기동안 배수만 실시했을 경우, 무산소층이 수심 8m에서 6m 이하로 증가하였다. 또한 해수유입 직후의 시화호 내에 잔존하는 무산소층이 해수에 포함된 용존산소를 급격히 소모시키는 특징을 나타냈다. 이러한 현상은 pH7.8${\sim}$8.2의 해수와 pH7.4이하의 저층수가 만나게 되어 산화작용을 촉진시켰기 때문인 것으로 해석된다. 해수유입이 크게 증가된 1998년 1월에는 전 수층의 용존산소가 10mg/l 이상을 나타냈다. 결론적으로 시화호 배수갑문 운용에 따른 수질개선을 위해서는 여름철에는 염분약층이 생성되지 않도록 해수의 유출량과 유입량을 늘리는 것이 효과적일 것으로 판단된다.

정상 신생아에서 용질배설 측정 의의에 관한 연구

최정훈,김미경,유기환,홍영숙,이주원,김순겸,Choi Jeong Hoon,Kim Mi Kyung,Yoo Kee Hwan,Hong Young Sook,Lee Joo Won,Kim Soon Kyum 대한소아신장학회 2000 Childhood kidney diseases Vol.4 No.1

목 적 : 출생 후 며칠간의 신생아의 creatinine수치는 모체의 영향을 받으므로 소변의 creatinine을 상수로 용질 배설 측정을 하는 것은 의미가 없을 수도 있다는 보고가 있어, 저자들은 신생아에서 일정한 간격으로 측정된 소변 creatinine이 차이가 있는가에 대하여 연구를 시행하게 되었다. 방 법 : 1998년 7월부터 8월까지 출생한 건강한 신생아를 대상으로 하여 두 번의 소변을 측정하였으며, 대조군으로는 그 기간 동안 입원한 소아과 병동의 환아를 대상으로 하였다. 신생아군은 49명이고 대조군은 33명이었으며, 신생아군의 첫 소변은 출생 첫날 시행하였고 비교군의 첫 소변시 나이는 $5.7{\pm}4.3$세였다. 신생아군과 대조군에서 처음과 두 번째 소변간의 간격은 2-3일이었다. 통계분석은 sigmastat 2.0을 사용하여 단순 선형 회귀 분석, t-test, paired t-test를 이용하였다. 결 과 : Creatinine mg/dL(Mean${\pm}$SD)은 첫 소변, 두 번째 소변에서 각각 신생아군은 $32.5{\pm}29,\;29.2{\pm}23$이고 대조군은 $57.7{\pm}51,\;58.8{\pm}51$으로 두 군 모두 첫 소변과 두 번째 소변의 소변 creatinine치는 차이가 없으며, 두 군간의 평균치의 비교분석은 유의한 차이를 보였다(P<0.01). 첫 소변과 두 번째 소변간의 creatinine평균치의 상관성에서 신생아군은 r=0.504(P<0.001)이고 대조군은 r=0.631(P<0.001)이었으며, creatinine/osmolality로 보정 후에도 각각 상관계수 0.506(P<0.001), 0.386(P<0.001)으로 유의한 상관관계를 보였다. 결 론 :신생아의 첫 소변과 두 번째 소변에서 creatinine의 비교분석에서는 유의한 차이가 없었으며 따라서 신생아에서도 용질배설 측정시 creatinine을 기준치로 사용할 수 있을 것으로 사료된다. Purpose: To evaluate whether the urinary creatinine concentration is a reliable reference value to standardize urinary solute excretion in a spot urine sample during the first week of life. Methods: Spontaneously voided urine specimens were obtained in 49 healthy full term neonates, and in 33 healthy older children with the median ages of $5.7{\pm}4.3$ years, two urine samples were available with an interval of 2 to 3 days. Urine creatinine concentration was determined by the Jaffe test(CoBAS, Integra, Roche, Swiss). Uurine osmolality was determined by the freezing point depression test(Multi-osmette, Precision, USA). Results: Mean urinary creatinine and osmolality values of the first urine samples were not significantly different with the second urine samples in each group. Mean urinary creatinine and osmolality values in neonates were significantly different from the older children of the each urine sample(P<0.01). In neonates, the mean of the urinary oreatinine/osmolality ratios was higher than that of the older children(P<0.01). The urinary creatinine and the creatinine/osmolality values of the first urine samples were closely correlated with those of the second samples in both two groups(P<0.001). Conclusion: The urinary creatinine concentration during the first day of life is relatively stable, even when corrected for urinary osmolality The urinary creatinine and the urinary creatinine/osmolality ratio, therefore, can be used to standardize the urinary excretion of solutes in the neonate.

역기하렌즈 착용 후 시력, 굴절이상 그리고 각막 난시의 상관성 분석

최정훈,류정완,이영춘,김현승,Jeong Hoon Choi,Jeong Wan Ryu,M,D,Young Chun Lee,M,D,Hyun Seung Kim,M,D 대한안과학회 2006 대한안과학회지 Vol.47 No.8

Purpose: To evaluate correlations with refractive error, astigmatism and uncorrected visual acuity after Ortho-K LKTM lens wear. Methods: Sixty-one eyes of 32 patients who had been wearing reverse geometry lenses for over 5 weeks were recruited. Uncorrected visual acuity, subjective refraction on retinoscopy, objective refraction measured by an autorefractometer, and corneal astigmatism were measured by corneal topography before, at 2 days, and 1, 3, and 5 weeks after lenses fitting. Results: Uncorrected visual acuity improved from 0.12±0.10 to 0.95±0.15 after 5 weeks. Subjective refraction on retinoscopy and objective refraction measures with the autorefractometer were -3.52±1.65D and -4.06±1.73D, respectively before wearing the lenses. These decreased to -0.08±0.40D and -1.98±2.04D, respectively after 5 weeks. The astigmatism detected by corneal topography improved from 0.93±0.49 to 1.20±1.03 after 5 weeks. Uncorrected visual acuity was correlated with the refractive error measured by subjective refraction with retinoscopy rather than that by objective refraction with the autorefractometer. Corneal astigmatism measured by corneal topography correlated with the refraction detected by the autorefractometer. Conclusions: Subjective refraction by retinoscopy rather than refraction found objectively using the autorefractometer, was highly correlated with uncorrected visual acuity (r=0.77~0.87) which seems to be useful in evaluating myopia patients. The astigmatism determined by autorefractometer examination had high correlation with that determined by corneal topography (r=0.51~0.76). This result appears useful in decisions related to the decentering of lenses.

국방 연구개발사업의 "운용자-개발자"간 연계성 향상을 위한 아키텍처 개발 방법에 대한 연구

최정훈,강석중,Choi, Jeong-Hun,Kang, Seok-Joong 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.6

In this paper, we have proposed Architecture Development methodology which can connect both operational view and system view. The Functional Architecture can connect both user and developer, and it is located between Activity analysis and System analysis. We suggest the new architecture methodology using the Functional Architecture and it provides effect to analyze the connection between user(military) and developer(enterprise) in Defence R&D and the new Architecture with the feedback analyze activity on a point of system view and the new architecture make the functional architecture.

배수갑문 운용에 따른 시화호의 수온과 염분 변화

최정훈,김계영,홍대벽,Choi, Jung-Hoon,Kim, Kye-Young,Hong, Dae-Byuk 한국지구과학회 2000 한국지구과학회지 Vol.21 No.5

1997년 2월부터 1998년 7월까지 총 33회에 걸쳐 시화호내 11개 정점에서 장기간 관측한 수온, 염분 자료를 이용하여 배수갑문운용에 따른 시화호의 물성변화를 파악하였다. 배수갑문을 통한 해수유통이 없었던 1997년 3월부터 1997년 6월까지 시화호내의 염분은 15psu 이하로 나타났으며, 약 11m 수심을 경계로 염분에 의한 강한 성층이 관측되었다. 배수갑문을 통한 해수유입이 시작된 1997년 7월에는 태양복사열의 증가로 표층수온이 급격히 상승하여 표층과 저층의 수온차가 약 10^{\circ}C$ 이상으로 나타났으며, 1997년 10월{\sim}$12월에는 표층에 비해 저층 수온이 상대적으로 높은 수온역전현상이 발생하였다. 1997년7월 배수갑문 개폐시기를 전 ${\cdot}$ 후로 배수갑문 내측에 위치한 정점에서 장기간 수온, 염분, 유속 및 유향을 조사한 결과, 해수유입시 수온과 염분이 대칭적인 분포를 나타내었으며, 이는 외해로부터 해수 유입시마다 저온, 고염의 해수가 시화호 내로 유입되었기 때문인 것으로 판단된다. 1998년 1월 이후에는 지속적인 배수갑문 개폐의 영향으로 시화호의 염분이 30psu 이상으로 해수화되었으며, 배수갑문 개폐 이전에 비해 성층이 크게 약화된 것으로 나타났다. The variations of physical properties due to inflow of seawater by sluice gates operation were observed in Shihwa Lake. The distributions of salinity and temperature were investigated at 11 stations during February, 1997 to July, 1998. The salinity of water mass in Shihwa Lake before gate operation was ranged below 15psu and strong stratification due to inflow of seawater was observed at the depth of 11 m. In July 1997, temperature difference of 10^{\circ}C$ was occurred between the surface and bottom water due to strong solar radiation. During October 1997 to February 1998, inversion of temperature distribution, which the temperature of bottom water was higher than that of surface water, was observed. In July 1997, temperature, salinity, current speed and current direction were investigated by RCM-7 at St.3 for 56 days. When sea water was intruded in Shihwa Lake, the symmetric distribution of temperature and salinity was observed and it seems to be resulted from inflow of seawater with low temperature and high salinity. After January 1998, salinity of Shihwa Lake was increased over 30psu due to continuous gate operation and the stratification was weakened.