• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.306-311
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• 2003

In this paper, we modeled the incident beam in order to analyze and evaluate the optical thin film device for wavelength division multiplexing in optical telecommunication network. As applied ray tracing method to the optical path, we were compared the accuracy of coupling efficiency simulated by two modeling methods. In the results of sinulation, ceil modeling method was preferred to annual modeling method in micro-optic device because of accuracy for coupling efficiency and Gaussian intensity distribution. In the results of optimal simulation for optical device using thin film filter, the distance (d1) between optical fiber and GRIN lens, the distance (d2) between GRIN lens and thin film filter and the coupling efficiency were 0.24 mm, 0.25 mm and -0.11 ㏈ respectively. As d2 was displaced at 0.25 mm and d1 was varied in order to evaluate the optimal value, d1 and maximum coupling efficiency were 0.24 mm and -0.35㏈, respectively. Then the results of experiment were corresponded to that of optimal simulation by cell modeling and it was possible to analyze the performance for optical device using thin film filter by the simulation.

• Korean Journal of Community Nutrition
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• v.26 no.2
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• pp.122-133
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• 2021

Objectives: This study evaluated the dietary habits and health behaviors of Korean adults according to their physical activity. Methods: Adults aged 19~64 years, who participated in the 2016~2018 National Health and Nutrition Examination Survey, were enrolled in this study. The subjects were classified into the physical inactivity group, aerobic physical activity group, strength exercise group, and combined exercise group. Results: Significant differences in skipping breakfast, frequency of eating out, dietary supplements, and alcohol drinking status were observed among physical activity groups (P < 0.001). The combined exercise group had the highest % KDRI of protein, vitamin A, thiamin, riboflavin, niacin, calcium, potassium, and iron (P < 0.001). The physical inactivity group had the highest obesity rate (35.1%), and they perceived their body image type to be obese. In the combined exercise group, 47.8% of respondents said they were in good health (P < 0.001). The health-related quality of life score of the physical inactivity group was the lowest, with a score of 0.94. The metabolic syndrome risk rate of the combined exercise group was lower at 0.62 times (95% CI, 0.51-0.75) than the physical inactivity group. Conclusions: The physical activity type was associated with metabolic syndrome. These results can be useful for supporting dietary education and physical activity programs for adults.

• Korean Journal of Community Nutrition
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• v.26 no.3
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• pp.200-210
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• 2021

Objectives: This study was conducted to investigate the awareness, knowledge, and behavior about food hygiene·safety among the elderly, and to provide basic data on this for their healthy dietary life. Methods: The study was conducted through a survey using a self-administered questionnaire on 473 elderly people over 60 years old living in Seoul and Gyeonggido. The questionnaire was designed to examine general characteristics, meal preparation status, the relation between awareness, knowledge, food hygiene behavior, and safety. Results: Among the particpants, 44.2% of the total people surveyed were elderly married couples, and 14.0% were single-person households. For men, most of the meals were prepared by the spouse (74.1%), and among women, 93.8% prepared their meals themselves (P < 0.001). 61.3% of the total subjects answered that they were very interested in food hygiene and safety. Men (32.4%) thought it was more difficult to collect food hygiene·safety information compared to women (14.0%, P < 0.001). The knowledge score about food hygiene·safety was 0.60 (P < 0.05) and the behavior score was 3.70 (P < 0.001). The correlation coefficient between knowledge and behavior according to food hygiene·safety was 0.371 (P < 0.001). Conclusions: The food hygiene·safety behavior of the elderly was associated with knowledge (P < 0.001). Therefore, food hygiene·safety education is necessary to ensure information availability and promote the health of the elderly.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.337-345
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• 2023

This study analyzes considerations for satellite orbit elements for the national micro-satellite system to effectively perform its mission in accordance with the operational concept, and compares the conventionally used Walker method to improve the performance of the satellite constellation method of the repeating ground track orbit. In satellite orbit element analysis, altitude candidate values of micro-satellite system, use of eccentricity and argument of perigee through frozen orbit, necessity of selection of appropriate orbit inclination, and satellite phasing rules for flying the same repeating ground track orbit are proposed. Based on these analysis results, the superiority of the constellation method of the repeating ground track orbit compared to the Walker method is verified in terms of revisit performance analysis, global coverage characteristics, and orbit consistency.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.39.2-40
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• 2021

본 연구는 《숭전역서》 혹은 《서양신법역서》 이후, 하국종(何國宗, ? -1767)과 매각성(梅殼成, 1681-1764) 등에 의해 기술된 《역상고성》 상하편에 실린 <일전역리>, <일전역법>, <일전표>를 바탕으로 태양의 운동을 자세히 살펴보았다. 《숭전역서》 <일전역리>에서는 티코브라헤의 혼합모형을 기반에 두었지만 태양의 운동은 톨레미(Ptolemy)의 이심모델(Eccentric model)과 차이가 없다. 그러나 <일전표>에 수록된 가감차의 값은 이퀀트모델(Equant model)을 기초로 한 것이었다. 《신법산서》 <일전표>에는 이 모델에 의한 계산법을 소개하고 있으나 계산의 오류를 범하였다. 태양 실측과의 어긋남, 태양의 운동을 기술하는 여러 상수들이 다시 얻어짐에 따라 《역상고성》 상하편의 <일전역리>에서는 코페르니쿠스 모델을 기초로 한 본륜-균륜 모델을 채택하고 있다. 이 모델을 기초로 한 가감차 계산 과정에 조금의 수학적 오류가 있지만 계산 결과에는 영향을 미치지 않았다. 그리고 <일전표>에 제시된 가감차값은 바로 이 모델을 기반으로 한 값들이다. <일전역법>에 제시된 동지 이후 태양의 실제 경도를 구하는 방법이 매우 구체적이다. 이 방법은 이후 《역상고성후편》의 <일전역법>도 그대로 따르고 있는데 다만 《역상고성후편》의 <일전역리>는 케플러의 타원모델을 채택하고 있다. 태양의 황경을 구하는 현재의 방법과 비교해보면 《역상고성》 <일전역법>에서는 그 기준이 동지이고 현재의 방법은 춘분점이라는 것만 다를 뿐이고, 방법은 동일하다. 다만 필요한 상수 값들이 시간에 따라 아주 느리게 변하기에 이 값들의 보정이 필요할 뿐이다. 이 방법은 조선에서 집필된 《세초류휘》, 《시헌기요》, 《추보속해》, 《추보첩례》에도 사용한 모델과 상수들은 다르지만 동일한 방법을 요약하고 있다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.53-68
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• 1997

Lake Shihwa, artificially constructed since 1988, shows a typical two-layered system depending on strong haline density stratification. Sill of the water gate at 6 m depth greatly restricts physical mixing with outer seawater and circulation in the lake, and contributes to the enhancement of anoxic environment in the deeper layer. With this enclosed physical environment, Lake Shihwa receives enormous amounts of organics, ammonia, and other pollutants from the neighboring municipal and industrial complexes through six major streams, thus developing biogeochemical differentiation of anoxic to suboxic environment in the high saline bottom water and highly eutrophicated brackish surface water. This study investigated vertical structures, biogeochemical behaviors and processes of various organic and inorganic compounds around oxic-anoxic interface. Nitrite and nitrate rapidly decreased below the pycnocline where about $1{\times}10^8$ tons of hypoxic bottom water exist. In this bottom layer, ammonium ranged from 75 to 360 ${\mu}M$ mainly resulting from deamination of dissolved organic nitrogen and ammonification of precipitated organic particles. Despite large amounts of surface water discharge and dilution by outer seawater inflow about $3{\times}10^8$ tons from April to August, 1996, bottom layer did not show any improvement of water quality and maintained highly reduced environment. The main reason seems to be imbalance between ineffectiveness of dilution due to shallow depth and large surface area, overloaded POC influx from the eutrophicated surface biological activity, and poor replenishment of oxygen in this artificial lake system. Therefore, as long as current salinity dependent two-layered system maintains with its physical limitations, any improvement of water quality cannot be foreseen in Lake Shihwa.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.3
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• pp.177-184
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• 1991

We have investigated geographical distribution and physico-chemical properties of water masses or water types at mid-bottom depth in the neighbouring sea of Cheju Island in August 1986. In 50m layer the Yellow Sea Bottom Cold Water(YSBCW) below $12^{\circ}C$ was observed in the northwestern area of Cheju Island, while the Tsushima Warm Water(TWW) with relatively high temperature$(>16^{\circ}C)$ and salinity more than 34.0 in its southeastern area extended as far as the coast of about 15km. Also, 50m layer at the outside stations of its southwestern area indicated relatively cold water temperature$(11-30^{\circ}C)$, probably due to southward transport of the Yellow Sea Bottom Cold Water(YSBCW . The Yellow Sea Warm Water(YSWW), the mixed water of the YSBCW and the TWW, ranged $13^{\circ}C$ to $16^{\circ}C$ in water temperature and was appeared mainly in the coastal and intermediate area of Cheju Island. And the relatively cold water in the southwestern area and the Tsushima Warm Water were more extensively distributed in 50m layer than the deeper layer. Horizontal distributions of nitrate and phosphate showed a pattern similar to that of water temperature. As it were, the Yellow Sea Bottom Cold Water had the highest concentration of nutrients, while southwestern outside stations had the lowest nutrient contents. Especially, the concentration of nitrate in the latter was remarkably low compared with the value at the other stations. It may be attributed to intensive vertical mixing by collision of the northward driven Tn with the southward driven YSBCW. Also, it was particular that the Tsushima Warm Water indicated relatively high silicate content corresponding to that of the Yellow Sea Bottom Cold Water. Based on the data of $\Delta Si/\Delta P$ ratio, it seems that the mid-bottom waters in this study area are younger than the surface or intermediate water in the Korean East Sea.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.4
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• pp.235-243
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• 2007

In order to understand the water mass properties in the southern location of the East Sea in the Korean coasts, the vertical distributions (down to 2,000 m deep) of water temperature, salinity, and dissolved inorganic nutrients were determined in April of 2005. The water mass of the surveyed location showed distinct vertical layers; highly saline surface, surface mixing layer, and thermocline of low temperature and salinity. The water layer below 300 m was characterized by water temperature lower than $1^{\circ}C$ and salinity 34.06, showing a representative water mass of the East Sea. The inorganic nutrients rapidly increased from 200m in the northern and southern parts around Ulleung Basin. A marked environmental difference was found between two layers separated by thermocline. The upper layer of the thermocline was oligotrophic and the vertical distribution of nutrient was very stable. In the water layer between 100 and 200m the nutrients slightly increased but remained still stable. From southern coasts to northeastern Ulleung, the water mass properties were site specific; the thickness of the surface mixed layer and nutricline showed a trend diminishing toward the northern locations probably due to diminished influence of Tsushima water. Redfield ratio (N:P=16:1) based on the ratio of chemical composition in organism revealed that nitrogen value continuously decreased to less than 16 with the water depth down to loom from the thermocline. The value in the water layer deeper than 100 to 200 m, thereafter, showed an increasing trend (over 16). This result was further supported by the finding of lower chlrophyll a content in the layer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.1
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• pp.1-14
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• 1978

To study the fluctuation of cold water in the East China Sea in summer heat budget of the Yellow Sea in winter was analysed based on the oceanographic and meteorological data compiled from 1951 to 1974. The maintain value of insolation was observed in December($160{\sim}190ly/day$), while the maximum in February ($250{\sim}260ly/day$). The range of the annual variation was found to be less than 50 ly/day. The value of the radiation term ($Q_s-Q_r-Q_h$) was remarkably small (mean 20 ly/day) in winter. It was negative value in December and January, and a positive value in February. The minimum total heat exchange from the sea ($Q_({h+c}$) was found value (471 ly/day) in February 1962, and the maximum (882 ly/day) in January 1963. The annual total heat exchange was minimum (588 ly/day) in 1962, and maximum (716 ly/day) in 1968. If the average deviation of mean water temperature at 50m depth layer were assumed to be the horizontal index ($C_h$) of colder water, $C_h$ is $C_h=\frac{{\Sigma}\limit_i\;A_i\;T_i}{{\Sigma}\limit_i\;A_i}$ where $A_i$ denotes the area of isothermal region and $T_i$ the value of deviation from mean sea water temperature. The vertical index ($C_v$) of cold water can be expressed similarly. Consequently the total index (C) of cold water equals to the sum of the two components, i.e. $C=C_h$＋$C_v$. Taking the deviation of mean sea surface temperature(T'w) in the third ten-day of Novembers in the Yellow Sea as the value of the initial condition, the following expressions are deduced : $C－T'w＝32.06 - 0.049$ $\;Q_T$ $C_h-T'w/2=12.20-0.019\;Q_T$ $C_v-T'w/2＝18.07-0.027\;Q_T$ where $Q_T$ denotes the total heat exchange of the sea. The correlation coefficients of these regression equations were found to be greater than 0.9. Heat budget was 588 ly/day in winter, and minimum water temperature of cold water was $18^{\circ}C$ in summer of 1962. The isotherm of $23^{\circ}C$ extended narrowly to southward up to $29^{\circ}N$ in summer. However, heat budget was 716 ly/day, and minimum water temperature of cold water was $12^{\circ}C$ in summer of 1968. The isotherm of $23^{\circ}C$ extended widely to southward up to $28^{\circ}30'N$ in summer. As a result of the present study, it may be concluded that the fluctuation of cold water of the East China Sea in summer can be predicted by the calculation of heat budget of the Yellow Sea in winter.

• Journal of Korean Medical classics
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• v.19 no.4
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• pp.12-26
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• 2006

유하간(劉河間), 주단계적학설전파이후(朱丹溪的학說전播以后), 인위명대모사의가용약적시후편중고한(因위明代某些의家用葯的時候偏重苦寒), 소이도치료상비위이극벌진양적폐두(所以도致了상脾胃而克伐眞陽的弊두). 종이위료교정착오(종而위了교正착오), 형성료주장온보적온보학파(形成了主張溫보的溫보學派). 설기(설己), 손일규(孫一圭), 張景岳等溫보학파강조주재생명적비위(張景岳等溫보學派强凋主宰生命的脾胃), 신명양기(腎命陽氣), 재변증론치방면입족우선(在辨證論治方面立足于先), 후천(後天), 중시비여신(重視脾與腎), 선용료감온적약물(善用了甘溫的藥物). 저대우교정착오기착극대적작용(저대于교正錯오起着極大的作用), 동시논증(同時논증), 이론전개상비위여신명이주제공탁료(理론展개上脾胃여腎命以主제공托了), 우기후자가심료명문학설적연구(尤其后者加深了命門학설的硏究). 장경악활동적명대시이주자학위국책적(張景岳活동的明代是以朱子學위國策的), 구비사변성적철(具비思辨性的哲) 학배영상(학背영上), 추상(推想)"리(理)"이발휘의(而발휘의) 학이론(학理론). 우시저시기의가문입족우(于是저시期의家門立足于) "황제내경(黃帝內經)" 여연기론진행료기초이론화임상연구(여연氣論진行了基초理론和임床硏究), 경악통과편찬(景岳通과編찬) "내경(內經)"이저작(而著作)"류경(類經)"등(等), 근거자기적임상실험(根据自己的임床실험), 제출료온보학설(提出了溫보학설). 타쟁론적초점시자기제출적(他爭론的焦点是自己提出的)"음부족론(음不足론)". 침대전현적쟁론상(침대前현的爭론上), 경악이하간여범계위대상경(岳以河間여凡溪위대象). "경악전서(景岳全書)" 지운(之云): "양자유하간출(襄自劉河間出), 이서화입론(以署火立論), 전용한량벌차양기(專用寒凉伐此陽氣), 기해이심(其害已甚), 뢰동원선생비위지화필수온양(賴東垣先生脾胃之火必須溫養), 연상미능진척일편지류(然尙未能盡斥一偏之謬), 이단계복출(而丹溪復出), 우입음허화동지론(又立陰虛火動之論) ...... 한량지폐우복성행(寒凉之弊又復盛行), 부선수기해자기거이불반(夫先受其害者旣去而不返), 후습이용자유미이불오(後習而用者猶迷而不悟)", 지분료하간여단계시(指분了河間여丹溪是)"헌기지마(軒岐之魔)". 저사주장현출독특적유해저(些主장현出독特的유解), 이대후대학설발전적봉헌(以대后代학설발展的奉헌). 경악침대단계적"양상유여(景岳침대丹溪的)"양상유여(陽常有餘), 음상부족(陰常不足)", "기유여변시화(氣有餘便是火)", 설성(설成)"양비유여(陽非有餘), 진양부족(眞陽不足)", "기부족변시한(氣不足便是寒)", "상화부시사화(相火不是邪火)", 대단계학설견지료비판적입장(대丹溪학설堅持了批判的立장). 단계제출(丹溪提出)"양음설(養陰說)"이수립음허화왕적병기이론(而수立陰虛火旺的病機理론), 타적(他的)'양유여음부족론(陽有餘陰不足論)'상(上), '음(陰)'주요지생식물질(主要指生殖物질), "양(陽)"지정욕(指情欲). 가시중심사상시강조생리적양생(可是中心思想是强조生理的양생), 몰수립실제(沒수立실제)'음허화왕(陰虛火旺)'적병기(的病機). 취시장경악실재완성료저사병기(就是張景岳실在完成了저些病機). 경악재(景岳在) "진음론(眞陰論)" '장형질설성진양적상(將形질설成眞陽的象), 이명문위기(以命문위其)', 용(用)"개부족(皆不足)"해석질병(解석질病), 이익화(以益火) 장수이론위치법(장水理론위治法). 이차제조좌우귀환(而且制造左右歸丸) 음이귀납료치료방법(飮以귀納了治료方法), 발휘진음(발휘眞陰), 진양학설이구조유계통적이론(眞陽學說而구造有系統的理론). 저양위의가적쟁론핵심리유상화론(저兩位의家的爭론核心里有相火論), 논자상교연구타문적이론이보고기결과(논者相교硏究他문的理론而보告其結果).