• 제목/요약/키워드: Catalytic effect

검색결과 827건 처리시간 0.03초

Activation Mechanism of Protein Kinase B by DNA-dependent Protein Kinase Involved in the DNA Repair System

  • Li, Yuwen;Piao, Longzhen;Yang, Keum-Jin;Shin, Sang-Hee;Shin, Eul-Soon;Park, Kyung-Ah;Byun, Hee-Sun;Won, Min-Ho;Choi, Byung-Lyul;Lee, Hyun-Ji;Kim, Young-Rae;Hong, Jang-Hee;Hur, Gang-Min;Kim, Jeong-Lan;Cho, Jae-Youl;Seok, Jeong-Ho;Park, Jong-Sun
    • Toxicological Research
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    • 제24권3호
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    • pp.175-182
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    • 2008
  • DNA-dependent protein kinase(DNA-PK) is involved in joining DNA double-strand breaks induced by ionizing radiation or V(D)J recombination and is activated by DNA ends and composed of a DNA binding subunit, Ku, and a catalytic subunit, DNA-PKcs. It has been suggested that DNA-PK might be $2^{nd}$ upstream kinase for protein kinase B(PKB). In this report, we showed that Ser473 phosphorylation in the hydrophobic-motif of PKB is blocked in DNA-PK knockout mouse embryonic fibroblast cells(MEFs) following insulin stimulation, while there is no effect on Ser473 phosphorylation in DNA-PK wild type MEF cells. The observation is further confirmed in human glioblastoma cells expressing a mutant form of DNA-PK(M059J) and a wild-type of DNA-PK(M059K), indicating that DNA-PK is indeed important for PKB activation. Furthermore, the treatment of cells with doxorubicin, DNA-damage inducing agent, leads to PKB phosphorylation on Ser473 in control MEF cells while there is no response in DNA-PK knockout MEF cells. Together, these results proposed that DNA-PK has a potential role in insulin signaling as well as DNA-repair signaling pathway.

아세톤에 의한 목재 조성분의 분리 (Separation of Wood Components by Acetone)

  • 송병희;안병준;백기현
    • Journal of the Korean Wood Science and Technology
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    • 제38권3호
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    • pp.230-241
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    • 2010
  • 본 연구는 산염이 첨가된 아세톤 용액으로 목질바이오매스를 가수분해하여 효과적으로 화학적 조성분을 분리할 수 있는 최적조건을 확립하는데 있다. 아세톤에 의한 목질바이오매스의 가수분해에서 $Al_2(SO_4)_3$은 우수한 촉매로 작용하였으며, 최적 농도는 0.01 M (6.3 wt%)였다. 본 실험에서는 아세톤과 물의 비율을 9 : 1로 맞추고 $Al_2(SO_4)_3$의 최적 농도조건에서 신갈나무재와 소나무재를 $200^{\circ}C$에서 45분 동안 가수분해하여 각각 92.7%와 92.4% 분해율을 나타냈다. 아세톤과 물의 비율이 8 : 2에서는 반응시간을 60분으로 연장하였을 경우 신갈나무재의 가수분해율은 92.7%였으나, 소나무재는 반응온도를 $210^{\circ}C$로 상승시켜야 신갈나무재에 버금가는 가수분해율을 얻을 수 있었다. 가수분해 온도와 시간을 증가시키면 가수분해산물로부터 분리, 회수되는 리그닌은 증가하였으나, 탄수화물 함량은 급격히 감소하는 경향을 보였다. 리그닌과 당의 회수량을 고려해 보면, 목질바이오매스의 최적 가수분해 조건은 아세톤과 물의 비율 8 : 2, 아세톤 용액에 대한 $Al_2(SO_4)_3$ 농도는 6.3 wt%, 가수분해 온도와 시간은 각각 $190^{\circ}C$와 60분으로 나타났고, 이 조건에서 당의 회수율은 목질바이오매스 전건중량 기준으로 신갈 나무재와 소나무재에서 각각 47.6%와 51.4%로 나타났고, 리그닌 회수율은 각각 18.2%와 13.7%로 측정되었다.

Are Bound Residues a Solution for Soil Decontamination\ulcorner

  • Bollag, Jean-Marc
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2003년도 International Symposium
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    • pp.111-124
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    • 2003
  • 기존의 오염물질을 제거하는 많은 화학적-물리적 정화 방법은 고비용과 오랜 시간을 요구하는 처리 과정 등의 단점을 갖고 있는 경우가 많았다. 따라서 흙과 수(水)환경내로 유입된 오염물질을 빠른 시간 내에 제거 할 수 있는 대안이 요구 되었다. 흙에 유출된 화합 물질 중 상당양은 흙에 의해 격리, 구속되고 이로 인해 일단 구속된 오염물질은 물과 유기 용매에 의해서도 잘 추출되지 않는 것으로 보고 되고 있다. 이러한 흙에 의한 오염물질의 비유동성(immobilization) 과정은 오염물질의 제거 기술의 대안으로 평가 될 수 있다. 기존 연구자들의 연구 결과, 화학적 혹은 물리적 반응 작용을 통해 오염물질을 흙을 구성하는 물질에 구속할 수 있음이 증명되었다. 이러한 과정 중 환경적 측면에서 볼 때, 화학적 반응이 더 우수하다 할 수 있다. 이는 강한 공유결합(covalent bonds)으로 연결될 경우 미생물의 활동이나 화학 처리로도 이를 분리하기 어렵기 때문이다. 리그닌(lignin) 분해에서 발생하는 휴믹(humic) 물질 등이 안정 된 화학적 연결을 통해 흙 매질 내에 오염물질과 결합하는 대표적 물질이다. 인위적으로 제조된 많은 화학물질은 자연적에서 발생하는 휴민산 발생원(humic acid precursors)과 닮았다. 따라서 화학물은 부식 과정(humifications process)동안 부식토(humus) 내로 병합(incorporate)되어 진다. 일단 이렇게 구성된 결합체는 생물체와 오염물질과의 반응을 방지하여 오염물질로 인한 생물체로의 독성을 감소시키는 역할을 하게 된다. 본 논문에서는 이러한 흙의 유기물(organic matter)와 오염물질과의 결합체에 대한 평가로서 다음의 항목에 대한 고찰이 이루어져야 함을 강조하였다. (a)결합체에서 생물체(biota)와의 반응에 의해 오염물질은 감소되는가\ulcorner (b) 모(parent) 화합물과 비교하여 복합체 생성물(complexed products)이 얼마나 덜 유독한가\ulcorner 그리고 (c)지하수 오염이 오염물질의 유동성 구속에 의해 얼마나 감소되는지\ulcorner

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이산화탄소에 의한 메탄올 합성 (제 1 보). Cu / ZnO 촉매계 연구 (Synthesis of Methanol from Carbon Dioxide (I). Study on Cu / ZnO Catalyst System)

  • 조성운;전기운;박대철;이규완
    • 대한화학회지
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    • 제33권5호
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    • pp.558-567
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    • 1989
  • 여러가지 조성비로 만든 Cu/ZnO계 촉매로 이산화탄소를 수소화시켜 메탄올을 합성하였다. 촉매제조시 각 성분의 조성비가 촉매활성에 미치는 영향을 조사하고 반응촉매에 대하여 표면적 측정(BET), 주사전자현미경 측정(SEM), X선회절분석(XRD), X선광전자분석(XPS) 등을 실시하여, 각 촉매의 촉매특성을 조사하고 촉매활성과의 연관성을 연구하였다. 반응생성물은 메탄올과 일산화탄소 뿐이었는데 메탄올의 생성은 CuO의 함량이 증가하면 그에 따라 점차 증가하였으나 CuO:ZnO의 조성비율이 30:70일 경우에 최대이었고, CuO가 70 이상이면 급격하게 감소하였다. 촉매에 대한 SEM 측정과 BET 측정결과에서 확인된 바와 같이 이점은 미세결정크기가 증가되고 표면적이 감소하는 점과 일치되었다. 또 XPS 측정결과에서 촉매표면상에서의 Cu의 농도는 Cu/Cu+Zn(atomic ratio)을 비교할 때 CuO의 함량이 50% 이상인 경우에서 현저히 감소하였다. 그리고 각 촉매들의 $Cu(2P^3)$에 대한 결합에너지의 수치상의 값은 거의 같았으나 환원된 상태의 $Cu(2P^3)$의 결합에너지는 소성된 상태의 것과 비교하여 낮아졌고, 표면에 분포된 Cu 는 대부분 $Cu^{\circ}$로 확인되었으며 CuO:ZnO의 조성이 30:70인 경우에서 최대가 되었다. 이것은 또한 CuO의 조성비율이 30인 때에 메탄올생성이 최대라는 실험결과와도 잘 일치하였다. 그리고 환원된 각각의 촉매로 펄스(pulse)형태의 반응기에서 이소프로판올을 분해시킨 결과 아세톤의 생성율이 프로필렌보다 컸음으로 이들은 염기성이 상대적으로 강한 촉매라고 추측하였다.

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NaY 제올라이트 촉매 상에서 젖산 탈수반응을 통한 바이오아크릴산 생산: Ca 함침 및 KOH 처리 영향 (Dehydration of Lactic Acid to Bio-acrylic Acid over NaY Zeolites: Effect of Calcium Promotion and KOH Treatment)

  • 김지찬;서수민;제정호
    • 청정기술
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    • 제28권4호
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    • pp.269-277
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    • 2022
  • 생물학적 효소 반응 산업의 발전으로 인해 바이오매스 자원으로부터 젖산을 대량 생산하는 것이 가능해짐에 따라 젖산의 추가적인 탈수 반응을 통해 고흡수성 수지 SAP, 디스플레이의 점접착제 등의 원료가 되는 아크릴산을 생산하는 친환경 공정이 많은 주목을 받고 있다. 본 연구에서는 젖산 탈수 반응에서 높은 활성을 가지나, 비활성화가 빠른 단점을 가지는 NaY 제올라이트 촉매의 산점 및 염기점을 조절하여, 높은 아크릴산 선택도를 장시간 유지 가능한 촉매를 개발하고자 하였다. 첫번째로 NaY 모촉매에 부분적으로 칼슘을 치환하여 산/염기도를 변화시키고자 하였으며, 이온 교환법과 초기습식 함침법을 모두 적용하여 그 효과를 탐색하였다. 그 결과 직접적으로 Ca를 함침하는 것이 선택도 및 안정성 측면에서 우수한 것을 확인하였으며, 16시간 반응 동안 40% 수율의 AA를 안정적으로 생산하였다. 산/염기 특성 분석 결과, 함침된 Ca는 주로 CaO 형태로 촉매 외피에 존재하면서, 젖산 탈수 반응을 위한 추가적인 염기점으로 작용하는 것으로 나타났다. 추가적으로 NaY 모촉매의 산세기를 약화시키면서 기공 내외적으로 Ca을 고르게 분산시키기 위해, KOH 처리를 통한 탈규소화 후, Ca를 함침하였다. 그러나 기존 Ca-NaY 촉매 대비 아크릴산 선택도가 증진되는 효과는 관찰하지 못하였다. 최종적으로 KOH 처리 촉매에서 Ca 담지양을 1 wt%에서 5 wt%로 증가시켜 염기점 양을 증진시켜 보았다. 그 결과, 기존 1 wt% Ca가 함침된 촉매에 비해 아크릴산 선택도를 65%까지 증진시킬 수 있었으며, 24시간 반응 동안 촉매 안정성 또한 꾸준하게 유지되어, 젖산 탈수 반응에서 염기점 조절이 선택도 및 안정성 향상에 중요한 변수임을 제시하였다.

폐포상피세포, 대식세포를 비롯한 각종 세포주에서 H2O2에 의한 Peroxiredoxin 동위효소들의 산화에 따른 불활성화와 재생 (Oxidative Inactivation of Peroxiredoxin Isoforms by H2O2 in Pulmonary Epithelial, Macrophage, and other Cell Lines with their Subsequent Regeneration)

  • 오윤정;김영선;최영인;신승수;박주헌;최영화;박광주;박래웅;황성철
    • Tuberculosis and Respiratory Diseases
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    • 제58권1호
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    • pp.31-42
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    • 2005
  • 배 경 : peroxiredoxins는 거의 모든 생명체에 공통적으로 보존되어 있으며, 최근에 발견된, 특이한 peroxidases로 인체에서 6가지 동위효소가 알려져 있으며, 산화스트레스에 대한 방어역할을 담당하고, $H_2O_2$신호전달 과정에서 중요한 조절 역할을 한다. peroxiredoxin은 $H_2O_2$ 처리 과정 중에서 자신이 산화되어 불활성화 되는데, 산화된 후 다시 재생되는 것으로 보고되나 그 생리적은 의미는 분명하지 않다. 이에 저자들을 폐상 피세포주, 대식세포주, 폐포모세혈관 내피세포주 및 기타 섬유모세포주 들에서 $H_2O_2$ 에 의한 Prx의 산화과정과 재생을 알아보고자 하였다. 방 법 : 수술 환자에서 적출한 정상 폐조직과, 세포주로는 평상시 산화 스트레스에 노출이 많을 것으로 예상되는 세포들로써, 폐포상피세포의 I 형 및 II 형 세포에서 기원한 A549, WI 26, Raw 264.7, Rat2,및 폐포 모세혈관 내피세포주 등을 이용하여 이를 $50{\mu}M$. $100{\mu}M$, $500{\mu}M$$H_2O_2$로 산화시켜 불활성화 한 후, 추적관찰 하였으며, 시간대 별로(0. 10, 30, 60, 120, 240, 480 분) 수확하여, 이를 1차원 non-reducing SDS-PAGE 및 2차원 전기영동로 분리 후, silver stain 과 Western blot으로 분석 하였다. 결 과 : 1. 실험에 사용된 모든 세포주에서, $H_2O_2$ 농도에 비례하여 peroxiredoxin I, II, III 의 불활성화를 관찰할 수 있었고, 10분에 최고로 불활성화되었다. 2. 산화된 이후, 30분경부터 peroxiredoxin 의 재생이 관찰되기 시작 하였으며, 2시간 이후부터 확연하였다. 3. 다시 재생된 peroxiredoxin은 $H_2O_2$투여로서, 다시 불활성화되어, 재생된 Prx 가 활성을 지닌 단백질임을 알 수 있었다. 4. 재생의 속도는 사용된 세포주마다 차이가 있었으며 (A549 >Raw 264.7 >$Rat_2$ >WI26), 단백질 합성억제제인 cycloheximide ($10{\mu}g/ml$) 존재 하에서도 변함 없이 관찰되었다. 결 론 : 세포 내에는 산화되어 불활성화된 peroxiredoxin을 재생하는 체계가 존재 하며, 이는 활성부위 cysteine을 갖는 다른 단백질에도 공통적으로 적용될 수 있는 분자 스위치일 가능성이 높으며, 산화에 의한 신호전달과정이나, 질병 모델에서 Prx 단백의 재생 체계의 이상과 병인에 관한 추가적인 연구가 필요할 것으로 사료된다.

가족계획과 모자보건 통합을 위한 조산원의 투입효과 분석 -서산지역의 개입연구 평가보고- (An Intervention Study on Integration of Family Planning and Maternal/Infant Care Services in Rural Korea)

  • 방숙;한성현;이정자;안문영;이인숙;김은실;김종호
    • Journal of Preventive Medicine and Public Health
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    • 제20권1호
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    • pp.165-203
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    • 1987
  • This project was a service-cum-research effort with a quasi-experimental study design to examine the health benefits of an integrated Family Planning (FP)/Maternal & Child health (MCH) Service approach that provides crucial factors missing in the present on-going programs. The specific objectives were: 1) To test the effectiveness of trained nurse/midwives (MW) assigned as change agents in the Health Sub-Center (HSC) to bring about the changes in the eight FP/MCH indicators, namely; (i)FP/MCH contacts between field workers and their clients (ii) the use of effective FP methods, (iii) the inter-birth interval and/or open interval, (iv) prenatal care by medically qualified personnel, (v) medically supervised deliveries, (vi) the rate of induced abortion, (vii) maternal and infant morbidity, and (viii) preinatal & infant mortality. 2) To measure the integrative linkage (contacts) between MW & HSC workers and between HSC and clients. 3) To examine the organizational or administrative factors influencing integrative linkage between health workers. Study design; The above objectives called for quasi-experimental design setting up a study and control area with and without a midwife. An active intervention program (FP/MCH minimum 'package' program) was conducted for a 2 year period from June 1982-July 1984 in Seosan County and 'before and after' surveys were conducted to measure the change. Service input; This study was undertaken by the Soonchunhyang University in collaboration with WHO. After a baseline survery in 1981, trained nurses/midwives were introduced into two health sub-centers in a rural setting (Seosan county) for a 2 year period from 1982 to 1984. A major service input was the establishment of midwifery services in the existing health delivery system with emphasis on nurse/midwife's role as the link between health workers (nurse aids) and village health workers, and the referral of risk patients to the private physician (OBGY specialist). An evaluation survey was made in August 1984 to assess the effectiveness of this alternative integrated approach in the study areas in comparison with the control area which had normal government services. Method of evaluation; a. In this study, the primary objective was first to examine to what extent the FP/MCH package program brought about changes in the pre-determined eight indicators (outcome and impact measures) and the following relationship was first analyzed; b. Nevertheless, this project did not automatically accept the assumption that if two or more activities were integrated, the results would automatically be better than a non-integrated or categorical program. There is a need to assess the 'integration process' itself within the package program. The process of integration was measured in terms of interactive linkages, or the quantity & quality of contacts between workers & clients and among workers. Intergrative linkages were hypothesized to be influenced by organizational factors at the HSC clinic level including HSC goals, sltrurture, authority, leadership style, resources, and personal characteristics of HSC staff. The extent or degree of integration, as measured by the intensity of integrative linkages, was in turn presumed to influence programme performance. Thus as indicated diagrammatically below, organizational factors constituted the independent variables, integration as the intervening variable and programme performance with respect to family planning and health services as the dependent variable: Concerning organizational factors, however, due to the limited number of HSCs (2 in the study area and 3 in the control area), they were studied by participatory observation of an anthropologist who was independent of the project. In this observation, we examined whether the assumed integration process actually occurred or not. If not, what were the constraints in producing an effective integration process. Summary of Findings; A) Program effects and impact 1. Effects on FP use: During this 2 year action period, FP acceptance increased from 58% in 1981 to 78% in 1984 in both the study and control areas. This increase in both areas was mainly due to the new family planning campaign driven by the Government for the same study period. Therefore, there was no increment of FP acceptance rate due to additional input of MW to the on-going FP program. But in the study area, quality aspects of FP were somewhat improved, having a better continuation rate of IUDs & pills and more use of effective Contraceptive methods in comparison with the control area. 2. Effects of use of MCH services: Between the study and control areas, however, there was a significant difference in maternal and child health care. For example, the coverage of prenatal care was increased from 53% for 1981 birth cohort to 75% for 1984 birth cohort in the study area. In the control area, the same increased from 41% (1981) to 65% (1984). It is noteworthy that almost two thirds of the recent birth cohort received prenatal care even in the control area, indicating that there is a growing demand of MCH care as the size of family norm becomes smaller 3. There has been a substantive increase in delivery care by medical professions in the study area, with an annual increase rate of 10% due to midwives input in the study areas. The project had about two times greater effect on postnatal care (68% vs. 33%) at delivery care(45.2% vs. 26.1%). 4. The study area had better reproductive efficiency (wanted pregancies with FP practice & healthy live births survived by one year old) than the control area, especially among women under 30 (14.1% vs. 9.6%). The proportion of women who preferred the 1st trimester for their first prenatal care rose significantly in the study area as compared to the control area (24% vs 13%). B) Effects on Interactive Linkage 1. This project made a contribution in making several useful steps in the direction of service integration, namely; i) The health workers have become familiar with procedures on how to work together with each other (especially with a midwife) in carrying out their work in FP/MCH and, ii) The health workers have gotten a feeling of the usefulness of family health records (statistical integration) in identifying targets in their own work and their usefulness in caring for family health. 2. On the other hand, because of a lack of required organizational factors, complete linkage was not obtained as the project intended. i) In regards to the government health worker's activities in terms of home visiting there was not much difference between the study & control areas though the MW did more home visiting than Government health workers. ii) In assessing the service performance of MW & health workers, the midwives balanced their workload between 40% FP, 40% MCH & 20% other activities (mainly immunization). However, $85{\sim}90%$ of the services provided by the health workers were other than FP/MCH, mainly for immunizations such as the encephalitis campaign. In the control area, a similar pattern was observed. Over 75% of their service was other than FP/MCH. Therefore, the pattern shows the health workers are a long way from becoming multipurpose workers even though the government is pushing in this direction. 3. Villagers were much more likely to visit the health sub-center clinic in the study area than in the control area (58% vs.31%) and for more combined care (45% vs.23%). C) Organization factors (admistrative integrative issues) 1. When MW (new workers with higher qualification) were introduced to HSC, it was noted that there were conflicts between the existing HSC workers (Nurse aids with less qualification than MW) and the MW for the beginning period of the project. The cause of the conflict was studied by an anthropologist and it was pointed out that these functional integration problems stemmed from the structural inadequacies of the health subcenter organization as indicated below; i) There is still no general consensus about the objectives and goals of the project between the project staff and the existing health workers. ii) There is no formal linkage between the responsibility of each member's job in the health sub-center. iii) There is still little chance for midwives to play a catalytic role or to establish communicative networks between workers in order to link various knowledge and skills to provide better FP/MCH services in the health sub-center. 2. Based on the above findings the project recommended to the County Chief (who has power to control the administrative staff and the technical staff in his county) the following ; i) In order to solve the conflicts between the individual roles and functions in performing health care activities, there must be goals agreed upon by both. ii) The health sub·center must function as an autonomous organization to undertake the integration health project. In order to do that, it is necessary to support administrative considerations, and to establish a communication system for supervision and to control of the health sub-centers. iii) The administrative organization, tentatively, must be organized to bind the health worker's midwive's and director's jobs by an organic relationship in order to achieve the integrative system under the leadership of health sub-center director. After submitting this observation report, there has been better understanding from frequent meetings & communication between HW/MW in FP/MCH work as the program developed. Lessons learned from the Seosan Project (on issues of FP/MCH integration in Korea); 1) A majority or about 80% of the couples are now practicing FP. As indicated by the study, there is a growing demand from clients for the health system to provide more MCH services than FP in order to maintain the achieved small size of family through FP practice. It is fortunate to see that the government is now formulating a MCH policy for the year 2,000 and revising MCH laws and regulations to emphasize more MCH care for achieving a small size family through family planning practice. 2) Goal consensus in FP/MCH shouBd be made among the health workers It administrators, especially to emphasize the need of care of 'wanted' child. But there is a long way to go to realize the 'real' integration of FP into MCH in Korea, unless there is a structural integration FP/MCH because a categorical FP is still first priority to reduce the rate of population growth for economic reasons but not yet for health/welfare reasons in practice. 3) There should be more financial allocation: (i) a midwife should be made available to help to promote the MCH program and coordinate services, (in) there should be a health sub·center director who can provide leadership training for managing the integrated program. There is a need for 'organizational support', if the decision of integration is made to obtain benefit from both FP & MCH. In other words, costs should be paid equally to both FP/MCH. The integration slogan itself, without the commitment of paying such costs, is powerless to advocate it. 4) Need of management training for middle level health personnel is more acute as the Government has already constructed 90 MCH centers attached to the County Health Center but without adequate manpower, facilities, and guidelines for integrating the work of both FP and MCH. 5) The local government still considers these MCH centers only as delivery centers to take care only of those visiting maternity cases. The MCH center should be a center for the managment of all pregnancies occurring in the community and the promotion of FP with a systematic and effective linkage of resources available in the county such as i.e. Village Health Worker, Community Health Practitioner, Health Sub-center Physicians & Health workers, Doctors and Midwives in MCH center, OBGY Specialists in clinics & hospitals as practiced by the Seosan project at primary health care level.

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