기후변화가 축산업에 미치는 경제효과

공현석(Hyeon Seok Gong),정경수(Kyeong Soo Jeong),김민경(Min Kyoung Kim),장재봉(Jae Bong Chang) 한국농식품정책학회 2020 농업경영정책연구 Vol.47 No.2

Adopting the Ricardian approach, this study investigates the economic effects of climate changes such as average temperature and rainfalls on Korean livestock farm revenue. The explanatory variables of empirical model were selected based on the previous literature. The pseudo-panel analysis is employed to resolve the imperfectness of the panel data. The results indicate that the control variables such as farming experience, household size, employment, ownership of heavy machinery, technology use, full-time farming and male owner affect the livestock farm revenue positively, and the age does negatively. The impact of summer average temperature on farm revenue was significant and negative, while that of winter was significant and positive. The marginal change of the summer temperature decrease farm revenue per head by 2.48%. This paper suggests that the livestock farm’s revenue responds sensitively to changes in summer and winter average temperature, and so we need to establish the long-term countermeasures against rapid climate change.

Evaluating Corrosion Resistance of Additive-Manufactured Ti–6Al–4V Using Electrochemical Critical Localized Corrosion Temperature

Jae‑Bong Lee,Dong‑il Seo,Hyun Young Chang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.1

A new concept to evaluate the localized corrosion resistance of stacked Ti alloys such as additive-manufactured (AM)Ti–6Al–4V alloy is proposed. Crevice corrosion of subtractive-manufactured (SM) Ti–6Al–4V occurred on the surfacebeneath the crevice former, whereas localized corrosion of the AM alloy occurred in any vulnerable site irrespective of thecrevice assembly. The electrochemical critical localized corrosion temperature (E-CLCT) was measured to evaluate theresistance of AM Ti–6Al–4V alloys to localized corrosion. The results showed that the localized corrosion of AM Ti–6Al–4V was attributable to the anisotropy and microstructure that resulted from rapid cooling, which were completely differentfrom the anisotropy and microstructure of SM Ti–6Al–4V. The optimum applied potential of AM Ti–6Al–4V in 25 wt%NaCl aqueous solution was deduced. The E-CLCT provides a useful criterion for determining the resistance of AM Ti alloysto localized corrosion and for comparing their resistances.

Evaluating Corrosion Resistance of Biomedical Ti-6Al-4 V Alloys Fabricated via Additive Manufacturing Using Electrochemical Critical Localized Corrosion Potential

Jae‑Bong Lee,Dong‑Il Seo,Hyeon‑Yeong Chang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

High entropy alloys (HEAs) have received tremendous attention in diferent applications because of their excellent corrosion resistance and superior mechanical properties. In the present work, a novel TiNbMoMnFe high entropy alloy systemwas synthesized and deposited on AISI 316L by DC magnetron sputtering system. The microstructure of the resulting thinflm was evaluated by grazing incidence X-ray difraction and feld emission electron microscope. It was found that the thinflm microstructure is composed of a crystalline solid solution (grain size of 76 nm) and an amorphous phase. The electrochemical investigations in Ringer’s solution revealed that a thin flm of 670 nm thick high entropy alloy has a low corrosioncurrent density of 0.024 μA cm−2, approximately 30% lower than that of the uncoated 316L. Meanwhile, the HEA thin flmshowed the highest pitting corrosion resistance and stability of the passive flm. The wettability examinations exhibited thatthe coated sample has a high contact angle of 90° in contrast to 60° for the uncoated ones. In summary, the TiNbMoMnFehigh entropy alloy thin flm shows great potential for use in biomaterial applications.

Real-Time External Compensation of Threshold Voltage Shift Using Double-Gate Oxide TFTs in a Gate Driving System

You, Bong-Hyun,Lee, Soo-Yeon,Hong, Seok-Ha,Lee, Jae-Hoon,Kim, Hyun-Chang,Ju, Ha-Ram,Choi, Moon-Chul,Jeong, Deog-Kyoon IEEE 2016 Journal of display technology Vol.12 No.9

<P>In order to suppress the malfunction caused by the shift of the threshold voltage (V-TH) of oxide thin film transistors (TFTs) to a negative value, double-gate TFTs are used in the shift register of the gate driving system to control V-TH by adjusting the top gate bias. The proposed circuit detects the current consumption of the shift register and adjusts V-TH so that the current consumption of the shift register is regulated within the desired value. The system includes a compensation algorithm, which can search for an optimized top gate bias in various circumstances such as process fluctuations and ambient temperature change. The proposed system provides a stable operation compared with a conventional structure especially at high temperature. Experimental results show that, in the conventional system without compensation, the output voltage of the shift register deteriorates at 80 degrees C and above, and the power consumption increases from 1.15 to 2.14 mW after 21600 s of continuous operation at 60 degrees C. On the other hand, the proposed system provides a stable gate output up to 100 degrees C and keeps the power consumption below 1.10 mW by adjusting the top gate bias responding to environment changes.</P>

農村地下水의 細菌 및 理化學的 所見

張鳳基,宋在商,金斗熙 慶北大學校 醫科大學 1987 慶北醫大誌 Vol.28 No.2

농촌지역 급수원의 세균 및 이화학적 성분을 우리나라 현행 음료수 수질 기준치와 비교하였고 지하수 오염의 요인등을 알아보고 지역고도, 취수형태, 오염원과의 거리, 우물의 깊이 등에 따른 성분 변화를 구명코자 1986년 4월 한달 동안 경북 금릉군 구성면 소재 27개 지점을 고도별로 선정하여 조사하였다. 대장균군은 27개 지하수 중 1곳만이 검출되지 않았으며, E. coli는 3곳만이 검출되지 않았고 일반 세균수가 100/㎖의 기준치 이상되는 곳이 9개소였다. 탁도, 염소이온, 암모니아성질소 및 질산성질소의 함량이 음료수 기준치보다 높게 나타난 곳이 많았으며 알칼리도, 경도, 불소 및 금속성분은 모두 기준치 이하로 나타났다. 지역고도가 높은 곳 일수록 세균학적 검사성적이 양호하게 나타났고 경도가 높았으며, 수온, 탁도, 암모니아성질소, 인산 및 수은 함량은 지대가 낮을수록 높게 나타나는 경향을 보였다. 우물물이 펌프나 자동펌프물에 비하여 세균학적 오염이 더 심했고 기타 성분도 대체로 높게 나타났다. 염소이온, 암모니아성질소 및 질산성질소의 함량과 MPN, E. coli 및 일반세균수와는 유의한 정상관을 하고 있었다. 변소나 축사와의 거리가 가까운 지하수 일수록 세균학적 오염도가 심한 것으로 나타났다. 비소와 수은함량은 전답과의 거리가 가까운 수원일수록 높게 나타났다. The bacteriological and physico-chemical analysis of rural ground water were undertaken, from April, 1 to April, 30 in 1986. Twenty seven samples of ground water were brought with ice-box within six hours to our laboratory. They were sampled from six wells, eight pumps, and three electric pumps located in Gu-sung Myean, Kum-ryung Gun, Kyungpook province. Almost all of the samples were contaminated by coliform bacteria except one, Hagang dong (see No. 27 in figure 1). Otherwise E. coli was isolated from 24 samples except three; -Ryimchondong(No.10), Yangkag dong (No.26)and Hagang dong (NO.26). In general bacteria count, nine samples, (No. 6, 7, 9, 13, 17, 21, 22, 23, and 24) were unsuitable to standard for drinking water. In 23 kinds of physico-chemical factors investigated, hydrogen ion, alkalinity, total hardness, flouride and all metals were within standard values for drinking water, but turbidity of some sites (for No.10, 11, and 16) were higher than standards, chlorine (for No. 7, 12, 13, 22, and 23), ammonia nitrogen (for No. 7, 13, 16, 22, and 23) and nitrate nitrogen (for No. 22 and 23), also. The lower altitude of sampling sites were the high bacteriological contamination, water temperature, turbidity, ammonia nitrogen, phosphate and mercury contents. In comparision with the water supplying style and bacteriological and physico-chemical contents, the wells were more remarkablely contaminated than pump or electric pumps. Correlation of bacteriological contamination with chlorine, ammonia nitrogen and nitrate nitrogen concentration were significantly positive, respectively. And it was highly negative correlation with the distance of contamination sources; -toilet or cattle shed. The shorter distance from farms were the higher in arsenic and mercury contents.

수영이 정신지체인의 체력요인과 도파민 농도에 미치는 영향

박봉섭,변재종,이창규 한국특수체육학회 2004 한국특수체육학회지 Vol.12 No.2

The purpose of this study was to find out the effects of swimming exercise programs on muscular function, cardiorespiratory function, agility, flexibility, balance, and dopamine concentration in the mentally retarded. The subjects were 5 mentally retarded students of high school for special education. The physical fitness factor and dopamine concentration were measured before and after 22-week swimming exercise(2 times/week, 60minutes/session). The statistical procedures used to the analysis were paired t-test. The results were as follows; First, the increase of physical fitness factors was shown in the cardiorespiratory function and flexibility. Second, the increase of dopamine concentration was shown. It could be concluded in this study that swimming exercise program had significant effects on the improvement of physical fitness and dopamine concentration of the mentally retarded.

PWR 발전소에서의 방사선장 특성

송명재,김희근,김봉환,장시영 대한방사선 방어학회 1992 방사선방어학회지 Vol.17 No.2

국내 원전의 주종인 가압경수로를 대상으로 스펙트로메트리 기법에 의한 감마, 중성자 그리고 베타 방사선장애 대한 특성조사를 수행하였다. 감마선장의 경우, HPGe 반도체 검출기로 구성된 휴대용 감마 스펙트로메타를 사용하여 측정한 결과, 평균 에너지 값의 분포는 가동정지중일 때 원전의 격납용기내에서 440∼780keV, 가동중일 때 원전의 보조건물내에서 280∼760keV로 나타났다. 가동중인 원전의 격납용기내 operation deck를 중심으로 5개 지점에 대하여 BMSS(Bonner Multiple Spectrometry System)을 사용하여 중성자선장을 조사하였다. BUNKI 코드를 사용하여 측정스펙트럼을 분해하였으며, 측정 장소에서의 평균 에너지 값의 분포는 20∼210keV이었다. 베타피폭원인 오염에 대하여 가동정지 상태인 원전의 격납용기내와 보조건물의 총 14개 지점의 고 방사성 오염지역에서 smearing 시료를 채취하여 표면장벽형 Si 반도체 검출기를 사용하여 에너지 스펙트럼을 측정하였다. 그 결과 부식생성물 60Co에 의한 베타 에너지가 지배적인 것으로 나타났다. Pheton, neutron and beta radiation fields were measurement at PWR plants which are the representative types of nuclear power plant operated in Korea. The photon energy spectra were measurement at locations in the auxiliary building during operation period and in the containment vessel(C/V) during shutdown period using a portable gamma spectrometer with a HPGe detector. The distribution of average energy was found to range from 440 to 780 keV in the C/V and from 280keV to 760keV in the auxiliary building respectively. The average neutron energy measured at the five locations round the operation deck in the C/V in operation using a BMSS(Bonn Multi-Sphere Spectrometer)ranged from 20 keV to 210keV. A computer code, BUNKI was used to unfold the spectrum. The beta energy spectra in the C/V asnd in the auxiliary building in annual outage were determined using 14 smear samples taken from the highly contaminated areas. The analysis showed that representative corrosion product, ??Co made main contribution to the beta energy field.

FR, NR 측정 방식을 이용한 IPTV 품질에 관한 연구

이재정(Jae-Jeong LEE),남기동(Ki-Dong Nam),김창봉(Chang-Bong Kim) 大韓電子工學會 2009 電子工學會論文誌-TC (Telecommunications) Vol.46 No.8

최근 국내 인터넷망의 개선과 TPS(Triple Play Service : 데이터+영상+음성) 서비스를 위한 가입자망의 고도화로 IPTV(Internet Protocol TV) 서비스의 품질에 대한 기대치가 급격히 높아지고 있다. 따라서, 가입자의 실시간 동영상 품질을 보장할 수 있는 IPTV 서비스 품질에 대한 국내 품질 기준 및 국제 표준의 제정이 시급히 필요하다. 본 논문은 서비스 사업자 네트워크의 특성과 유사한 환경에서 시험하기 위해 방송/VoD(Video on demand)를 제공하는 헤드엔드 영역과 상용 네트워크 특성을 나타내는 트래픽/라우팅 부하 생성 장비와 네트워크 Impairment 장비 및 다수의 이기종 라우터를 포함하는 네트워크 영역과 가입자 셋탑박스 영역으로 테스트베드를 구축하였다. 그리고 구축된 환경을 이용하여 서비스 환경의 변화에 따른 품질시험으로 IPTV 서비스의 품질기준 결정에 필요한 특성을 제시한다. Recently, as the expectation about the IPTV (Internet Protocol TV) service quality is rapidly increased by the development of the national high-speed internet and TPS (the Triple Play Service : data + image + audio) service. Therefore, the enactment of the national quality standards about the IPTV service quality guaranteeing the real time video quality of a subscriber and the international standards are hastily needed. This paper built a test bed with the network domain and the subscriber set-top box domain including the headend area and commercial network characteristic in order to test in the environment which is similar to the characteristic of the service business network. And by using the constructed environment, the characteristics required for SLA(service Level Agreement) of the IPTV service are presented as the quality test according to the service environment change.

열처리된 AgInS₂박막의 defect 연구

박창선,김봉재,홍광준 조선대학교 에너지.자원신기술연구소 2002 에너지·자원신기술연구소 논문지 Vol.24 No.1

AgInS₂단결정 박막은 수평 전기로에서 합성한 AgInS₂다결정을 증발원으로하여, hot wall epitaxy(HWE) 방법으로 증발원과 기판(반절연성-GaAs(100))의 온도를 각각 680℃, 410℃로 고정하여 단결정 박막을 성장하였다. 이때 단결정 박막의 결정성은 광발광 스펙트럼과 이중결정 X-선 요동곡선(DCRC)으로부터 구하였다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 293K에서 운반자 농도와 이동도는 각각 9.35×10^(16)/㎤, 294 ㎠/V·s였다. 또한 광흡수 spectra에서 energy band gap의 온도 의존성 E_(g)(T)는 2.3165eV-(9.89×10_(-3)eV/K)T² / (T+2930K)임을 확인하였다. 성장된 AgInS₂단결정 박막을 Ag, S, In 분위기에 열처리하여 10K에서 photoluminescience(PL) spectra를 측정하여 점 결함의 기원을 알아보았다. PL 측정으로부터 얻어진 V_(Ag), Vs, Ag_(int), 그리고 S_(int)는 주개와 받개로 분류되어졌다. AgInS₂단결정 박막을 S분위기에서 열처리하면 p형으로 변환됨을 알 수 있었고, In 분위기에서 열처리하면 열처리 이전의 PL spectra를 보이고 있어서 I₂, I₁ 및 S, A emission에 의한 PL peak에는 영향을 주지 않는다고 보았다. A stoichiometric mixture of evaporating materials for AgInS₂single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, AgInS₂ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE) system. Temperature of the source and substrate were 680℃ and 410℃, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of AgInS₂single crystal thin films measured from Hall effect by van der Pauw method are 9.35×10^(16)cm^(-3) and 294 cm²/V·s at 293 K, respectively. From the optical absorption measurement, the temperature dependence of the energy band gap bn-AgInSz single crystal thin films was found to be E_(g)(T) = 2.1365 eV - (9.89 x10^(-3) eV) T²/(2930 + T). After the as-grown AgInS₂single crystal thin films was annealed in Ag-, S-, and In-atmospheres, the origin of point defects of AgInS₂single crystal thin films has been investigated by using the photoluminescence(PL) at 10 K. The native defects of V_(Ag), Vs, Ag_(int), and S_(int) obtained from PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere converted AgInS₂single crystal thin films to an optical p-type. Also, we confirmed that In in AgInS₂/GaAs did not form the native defects because In in AgInS₂single crystal thin films did exist in the form of stable bonds.

폴리머碍子의 自然劣化現狀에 關한 硏究

張善奉,張錫九,沈在明 大田産業大學校 2000 한밭대학교 논문집 Vol.17 No.1

In this paper, for the estimation of its long-term reliability, we took polymer insulators used at the seashore during about 2 or 4 years. it used a variety of methods to understand deterioration characteristics for these polymer insulators. For investigating the degree to change inherent characteristics, we performed electrical flashover voltage test, leakage current measurement. and for examining surface properties of its materials, we utilized SEM. FTIR-ATR and contact angle meter. These test results had been compared virgin ones with aged samples in the field. In the electrical flashover test with all samples, although it had a slight reduction. the flashover voltages was in the boundary of KS criteria. The results showed that the contact angles of aged sample surfaces were larger than that of virgin ones. however, sample B which had a short experience in the field showed contact angle to be reduced. Because of the environmental impact on polymer insulators, exposed for many years under natural conditions. it was verified the insulator material at the surface of the insulators undergoes a slight degradation process as the micro cracks at the inspection utilizing SEM. In conclusion, the polymer insulators aged during 2 or 4 years under our national environment showed agreeable performance. For exactly evaluating its long-term performance, we need to cumulate data that was the results to analyzing characteristics on polymer insulators.