Toward one Korea; The Neautralized Unification of Korea, by In K hwang. Cambridge, Mass.: Schenkman Publishing Company. $15.95 cloth $8.95 paperback.

Nearly 30 years after the end of a war that devastated both North and South Korean, either side has found the path to civil communication, let alone a peace treaty. The "threat from the North" remains the justification of the ruthless authoritarian governments that have ruled in Seoul. And fear of representative institutions has also made the North the most closed of all communist societies.

It is this state of affairs that serves as background to a useful, carefully researched and documented work, "The Neutralized Unification of Korea," by Prof. In K. Hwang of Bradley University.

The Korean Peninsula has historically been the land route of invading armies from China and Russia in their efforts to reach Japan, and conversely by Japan to reach northward. Thus the strategic concerns of Korea's neighbors come in for considerable review here. In Hwang's view, neutralization would serve the security interests of the Soviet Union, China, and Japan by preventing either Soviet or Chinese domination of the peninsula and thus easing tensions that spill over into Japan.

For the United States, "Korean neutralization would alternatively serve as a "face-saving' device for allowing orderly disengagement from korea without leaving a vacuum for another power to fill."

There is logic, of course, in what Hwang writes. So much so that little that he says in new to strategists in Washington, Tokyo, Moscow, or Peking. Yet to date no new understanding has been reached. There is reason then to wonder whether these big powers don't in fact conceive that a divided peninsula serves their interests better. Would, for example, American and Japanese business ventures in South Korea fare as well in a unified country constantly facing the potential clash between communist-controlled or free-market economies? The motivations of the big powers deserve more critical study than Hwang provides.