순 (純) Al 주괴의 (鑄塊) 응고조직에 미치는 주형 (鑄型) 점결재의 (粘結材) 영향에 관한 연구

최창옥,이계완 ( Chang Ock Choi,Kye Wan Lee ) 한국주조공학회 1985 한국주조공학회지 Vol.5 No.1

The effects of mold binders on the formation of equiaxed zone of 99.8% AL ingots were studied with various sand molds and metal mold. The formation of equiaxed crystals are increased by furan, cement, CO₂and metal mold, and decreased by greensand and shell mold. Pouring temperature moat be kept as low as possible to get a fine grain Structure and to increase of volume of equiaxed zone. The effect of surface roughness on volume of equiaxed zone were depend upon by the kind of mold binders. These are caused by separation of crystals from the mold wall in the initial stage of solidification before formation of the stable solid skin.

건식조건하에서 (乾式條件下) 회주철의 (灰鑄鐵) 로링마모에 (磨耗) 관한 연구

최창옥,김동윤 ( Chang Ock Choi,Dong Yun Kim ) 한국주조공학회 1983 한국주조공학회지 Vol.3 No.2

This study has been carried out to investigate into the difference of rolling life and rolling wear characteristics for various gray cast iron under unlubricated dry rolling condition by amsler type wear test with 9.09% sliding. The results obtained from this study are summerized as follows: 1) It has been found that the amount of rolling wear id decreased when tensile strength and hardness are low, and then the rolling life up to generation of abnormal wear is conspicuously increased. 2) At the given condition the amount of rolling wear has been found to decrease as carbon equivalent of gray cast iron increases and resistance of crack propagation is an important factor on improvement of wear characteristics. 3) The amount of rolling wear is increased with increasing rolling revolution and wear of gray cast iron under dry rolling condition is characterized by three modes; initial wear, stationary wear and abnormal wear. 4) It has been found that the amount of rolling wear is increased with increasing maximum compressive stress and extremely increased when maximum compressive stress is over 59.1㎏.f/㎜

주형점결재에 (鑄型粘結材) 의한 Al-Cu 합금의 응고조직에 관한 연구

최창옥,이계완 ( Chang Ock Choi,Kye Wan Lee ) 한국주조공학회 1986 한국주조공학회지 Vol.6 No.1

The effects of various kind of molds on cast structures were studied. Al-4.5% C1i and Al-8% Cu alloys. Five kinds of sand molds which were mixed with different binders and a metal mold were used. Density, dendrite arm spacing and dendrite arm length of the cast alloys were greatly affected by quantities and materials of mold binders. The macrostructures examined were entirely equiaxed grains with little influences of types of molds. It is possibly due to the separation of growing crystals from the mold wall at the inital stage of solidification.

장년이후 고령의 대퇴경부 골절에서 내고정 및 인공관절 치환술에 대한 임상적 고찰

최창옥,김연일,최희수,김영호,송준민,고광곤 (Chang Uk Choi,Yun Il Kim,Hee Soo Choi,Young Ho Kim,Jun Min Song and Kwang Kon Ko) 대한고관절학회 1989 Hip and Pelvis Vol.1 No.1

CO2 주형의 (鑄型) 붕괴성에 (崩壞性) 대한 잔류강도의 (殘留强度) 변화에 관한 연구

최창옥,성경훈 ( Chang Ock Choi,Kyong Hun Sung ) 한국주조공학회 1983 한국주조공학회지 Vol.3 No.3

Effects of retained compression strength on the collapsibility of CO₂mold sand using sodium silicate were studied. The results obtained from the experiment are summurized as follows; 1) The sand mixtures Increased their compression strength and retained compression strength when content of sodium silicate is high or mole ratio of sodium silicate is high. 2) Increase of retained strength has a maximum value at temperatures about 200℃. When the sample reached 800℃, the binder bridge are homogeneous The retained strength is increased 3) Decrease of retained strength at temperatures over 200℃ is caused by pore formation and additives of seacoal markedly accelerated pore formations.

후란자경성 (自硬性) 주형용 (鑄型用) 국산인조규사의 (國産人造硅砂) 활용에 관한 연구

최창옥,이상윤 ( Chang Ock Choi,Sang Yun Lee ) 한국주조공학회 1981 한국주조공학회지 Vol.1 No.3

N/A An emphasis has been placed on the importance of selecting a sand for furan sand process, which ie affected by the properties of sand. Investigations have been carried out to use the domestic artificial sands for the furan sand process. For laboratory investigations, the sands have been prepared and tested for chemical analysis, loss on ignition, sieve analysis, AFS grain fineness number, grain shape, PH value, acid demand, surface shape, theoretical surface area, moisture absorption, crushing durability and compressive strength and S. S. I. of molding sands. Most commercial sands have been found to be able to be used. The main requirement of the sands has been shown to be that 3 or 4 screen sands, AFS no.40-70 (or 100), of low acid demand, good surface area and good grain shape require less resin and catalyst to give an adequate strength.

취임사

최창옥 ( Chang Ock Choi ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.1

논문편 - 의생활편 : 도시주부의 의생활 관리태도

최창옥 ( Chang Ok Choi ) 대한가정학회 1978 Family and Environment Research Vol.16 No.4

디지털 시대의 국가 미래 비전과 지방분권 전략

최창옥(Chang Ok Choi) 미래학회 2019 미래연구 Vol.4 No.2

중앙집권관치는 유효기간이 끝났다. 디지털 경제는 네트워크 기반의 수평, 분권적, 개방적 협업생태계가 지배하고, 빠른 변화와 고도의 불확실성을 특징으로 한다. 우리의 중앙집권 관치는 이런 변화된 환경에서 신속, 정확하고 효율적인 의사결정이 어렵다. 이 글에서는 지방분권자치를 그 대안으로 제시한다. 이를 위해 헌법 개정을 전제하지 않고 실천할 수 있는 세 가지 원칙을 제시한다. 첫째로 정부의 의사결정 단위를 경량화 하여 작고 효율적인 단위로 나누고 다원화하여 권한과 책임의 관계를 단순하고 명확하게 할 필요가 있다. 둘째로 재정의 지방분권화다. 지방분권자치의 알파와 오메가는 재정분권이고 재정분권은 지방세의 과세 자주권을 전제로 한다. 지방세법이 정한대로 우선 지방세의 세목과 세율을 지방의 재정수요에 따라 자율적으로 결정할 수 있도록 해야 한다. 셋째로 중앙은 전국차원의 사회 안전망, 지방은 산업 육성으로 역할을 전문화해야 한다. 변화와 불확실성 시대에는 중앙정부가 정확한 판단을 한다는 보장이 없다. 오히려 확률적으로 오판할 가능성이 더 높고, 그 폐해는 전국적이 되고, 기회비용 손실도 만만치 않다. 따라서 중앙정부의 역할은 개인과 기업으로 하여금 실패의 위험을 감수하고 혁신과 실험적 비즈니스에 과감하게 도전할 수 있도록 안전판이 되어줄 생산적인 사회안전망을 제공하는 것이다. 한편 지방분권자치는 한반도 통일과정에서 민주적 정당성을 확보하고, 통일 이후 남북한 화합과 공생발전을 보장할 합리적인 준비가 될 수 있다. 이 차원의 지방분권 자치는 헌법 개정을 필요로 한다. 이를 위해 북한 주민들이 자유의사와 민주적 절차로 우리의 자유 민주헌정체제에 편입할 수 있는 절차와 방법을 열어주고, 통일이후 남북한 지역갈등 해소 및 공생발전과 단일 국가 정체성 확보 등을 위한 실천적 수단도 필요하다. 따라서 북한의 연방제 통일 방안과는 다른 우리 방식의 연방국가형 지방분권자치 모델, 즉 북한지역의 일부 또는 전부가 집단적 의사에 따라 우리의 자유민주주의 헌정체제에 편입할 수 있는 길을 열어주고, 체제의 이질성이 현격한 북한주민들을 우리 헌정체제로 유도할 수 있는 통일과정 관리 방안도 요구된다. The validity of centrally controlled government management has expired. The digital economy is dominated by network-based horizontal, decentralized and open collaborative ecosystems, characterized by rapid changes and a high degree of uncertainty. Our centralized government system is difficult to make quick, accurate and efficient decisions in this changing environment. This paper presents decentralized autonomy as an alternative. To this end, we present three principles that can be implemented without preconditioning a constitutional revision. First, it is necessary to make the government decision-making unit lightweight and divide it into smaller and more efficient units, and diversify to make the relationship between authority and responsibility simple and clear. Second is a fiscal decentralization. Alpha and Omega of decentralized autonomy are fiscal decentralization, which assumes the tax autonomy of local government. As prescribed by the local tax law, the taxable and tax rates of local government should be autonomously determined according to local financial needs. Third, the central government should specialize in social safety nets at the national level, while local governments should be in charge of industrial policies in their regions. In times of rapid change and high uncertainty, there is no guarantee that the central government will make accurate judgments. Rather, they are more likely to be wrongly misjudged, causing great damages in national level, and the daunting loss of opportunity cost as well. The role of the central government is therefore to provide a productive social safety net that will enable individuals and businesses to take risks of failure, and provide a safeguard for the private sector to boldly challenge innovation and experimental business. On the other hand, decentralized autonomy can be a rational preparation for the process of unification of the Korean peninsula, while securing democratic legitimacy as well as ensuring inter-Korean win-win development and harmonious coexistence there after. Decentralized autonomy at this level requires a constitutional amendment. To this end, we need to open a process and method for North Koreans to join our liberal democratic constitution with free will and democratic procedures, and also need practical measures for resolving regional conflicts, reviving coexistence, and securing a single national identity after unification. Thus, the federal decentralization model, which is different from North Korea’s federal reunification plan, opens the door for some or all of North Korea to join our liberal democratic constitutional system according to collective intentions. There is also a need for a unification process management plan that can lead North Korean citizens with great heterogeneity to our constitutional system.

후란자경성 (自硬性) 주형의 (鑄型) 제조법

최창옥 ( C . O . Choi ) 한국주조공학회 1981 한국주조공학회지 Vol.1 No.2